Mercurial > hg > ascension / changeset

--- a/Makefile	Mon Aug 18 23:11:50 2025 +0200
+++ b/Makefile	Tue Aug 19 18:05:35 2025 +0200
@@ -26,7 +26,7 @@
 all: snake
 
 snake: build/lib/libascension.a FORCE
-	@cd test/snake && $(MAKE)
+	@cd demo/snake && $(MAKE)
 
 build/lib/libascension.a: config.mk FORCE
 	@cd src && $(MAKE)
@@ -43,7 +43,7 @@
 
 update-rules:
 	make/update-rules.sh src
-	CFLAGS=-I../../src make/update-rules.sh test/snake
+	CFLAGS=-I../../src make/update-rules.sh demo/snake
 
 FORCE:
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/snake/Makefile	Tue Aug 19 18:05:35 2025 +0200
@@ -0,0 +1,65 @@
+# Copyright 2023 Mike Becker. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#   1. Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#
+#   2. Redistributions in binary form must reproduce the above copyright
+#      notice, this list of conditions and the following disclaimer in the
+#      documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+
+include ../../config.mk
+
+BUILD_DIR=$(srcdir)/build/snake
+LIB_ASCENSION=$(srcdir)/build/lib/libascension.a
+CFLAGS += -I$(srcdir)/src $(CPPFLAGS)
+
+all: $(BUILD_DIR) $(BUILD_DIR)/snake FORCE
+	@echo "Demo game 'snake' successfully built."
+	@cp -Ruf $(srcdir)/shader $(BUILD_DIR)/
+	@cp -Ruf $(srcdir)/fonts $(BUILD_DIR)/
+	@cp -Ruf textures $(BUILD_DIR)/
+	@cp -Ruf shader $(BUILD_DIR)/
+	@echo "Assets for demo game 'snake' successfully copied."
+
+$(BUILD_DIR):
+	mkdir -p $@
+
+$(BUILD_DIR)/snake: $(BUILD_DIR)/snake.o $(LIB_ASCENSION)
+	@echo "Linking snake..."
+	$(CC) $(LDFLAGS) -o $@ $^
+
+$(LIB_ASCENSION):
+	test -f "$@"
+
+FORCE:
+
+$(BUILD_DIR)/snake.o: snake.c ../../src/ascension/core.h \
+ ../../src/ascension/error.h ../../src/ascension/context.h \
+ ../../src/ascension/datatypes.h ../../src/ascension/window.h \
+ ../../src/ascension/glcontext.h ../../src/ascension/scene.h \
+ ../../src/ascension/scene_node.h ../../src/ascension/transform.h \
+ ../../src/ascension/camera.h ../../src/ascension/input.h \
+ ../../src/ascension/behavior.h ../../src/ascension/ui.h \
+ ../../src/ascension/text.h ../../src/ascension/font.h \
+ ../../src/ascension/mesh.h ../../src/ascension/texture.h \
+ ../../src/ascension/sprite.h ../../src/ascension/2d.h \
+ ../../src/ascension/shader.h
+	@echo "Compiling $<"
+	$(CC) -o $@ $(CFLAGS) -c $<
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/snake/shader/player.glsl	Tue Aug 19 18:05:35 2025 +0200
@@ -0,0 +1,16 @@
+layout(location = 0) out vec4 diffuse;
+in vec2 uvcoord;
+
+uniform sampler2D map_albedo;
+uniform sampler2D map_color;
+uniform vec4 color;
+
+void main(void) {
+    // TODO: use greyscale texture instead
+    vec4 color_map_pixel = texture(map_color, uvcoord);
+    if (color_map_pixel.a > 0) {
+        diffuse = color * color_map_pixel * texture(map_albedo, uvcoord);
+    } else {
+        diffuse = texture(map_albedo, uvcoord);
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/snake/snake.c	Tue Aug 19 18:05:35 2025 +0200
@@ -0,0 +1,598 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ * Copyright 2023 Mike Becker. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <ascension/core.h>
+#include <ascension/ui.h>
+#include <ascension/sprite.h>
+#include <ascension/2d.h>
+#include <ascension/shader.h>
+
+#include <cx/printf.h>
+#include <cx/linked_list.h>
+
+#define TEXTURE_2D_COUNT 3
+static AscTexture tex2d[TEXTURE_2D_COUNT];
+#define TEXTURE_PLAYER &tex2d[0]
+#define TEXTURE_PLAYER_COLOR_MAP &tex2d[1]
+#define TEXTURE_BACKDROP &tex2d[2]
+
+#define SHADER_ID_PLAYER 1
+
+#define BACKDROP_SCENE asc_window_scene(0)
+#define MAIN_SCENE asc_window_scene(1)
+#define HUD_WIDTH 400
+
+enum MoveDirection {
+    MOVE_UP,
+    MOVE_LEFT,
+    MOVE_DOWN,
+    MOVE_RIGHT
+};
+
+static asc_transform rotations[4];
+static asc_vec2i directions[4];
+
+typedef struct {
+    asc_color color;
+    enum MoveDirection direction;
+    enum MoveDirection target_direction;
+    /**
+     * The speed in tiles per second.
+     */
+    float speed;
+    /**
+     * A linked list of vec2u elements describing the current trace.
+     */
+    CxList *trace;
+    /**
+     * The new position of the player when @c reset_position is @c true.
+     */
+    asc_vec2i new_position;
+    unsigned health;
+    bool reset_position;
+    uint8_t number;
+} Player;
+
+#define GAME_FIELD_SIZE 32
+#define GAME_FIELD_TILE_SIZE 32
+
+/** The bit in the tile data indicating if the tile exists. */
+#define GAME_FIELD_TILE_EXISTS_FLAG  0x80
+/** The bits in the tile data that identify the owner. */
+#define GAME_FIELD_TILE_OWNER_MASK   0xF
+
+typedef struct {
+    AscSceneNode *nodes[GAME_FIELD_SIZE][GAME_FIELD_SIZE];
+    int8_t tile_data[GAME_FIELD_SIZE][GAME_FIELD_SIZE];
+} GameField;
+
+
+#define GAME_STATE_MENU 0
+#define GAME_STATE_PLAYING 1
+#define GAME_STATE_GAME_OVER 2
+
+typedef struct {
+    int state;
+    GameField *field;
+    Player *players[4];
+} GameState;
+
+GameState game = {0};
+
+static void globals_init(void) {
+    asc_transform_identity(rotations[MOVE_UP]);
+    asc_transform_roll(rotations[MOVE_LEFT], asc_rad(-90));
+    asc_transform_roll(rotations[MOVE_RIGHT], asc_rad(90));
+    asc_transform_roll(rotations[MOVE_DOWN], asc_rad(180));
+    directions[MOVE_UP] = ASC_VEC2I(0, -1);
+    directions[MOVE_LEFT] = ASC_VEC2I(-1, 0);
+    directions[MOVE_DOWN] = ASC_VEC2I(0, 1);
+    directions[MOVE_RIGHT] = ASC_VEC2I(1, 0);
+}
+
+static void textures_destroy(void) {
+    asc_texture_destroy(tex2d, TEXTURE_2D_COUNT);
+}
+
+static void textures_init(void) {
+    asc_texture_init_2d(tex2d, TEXTURE_2D_COUNT);
+    asc_texture_from_file(TEXTURE_PLAYER, "player.png");
+    asc_texture_from_file(TEXTURE_PLAYER_COLOR_MAP, "player-color-map.png");
+    asc_texture_from_file(TEXTURE_BACKDROP, "backdrop.png");
+    asc_gl_context_add_cleanup_func(asc_active_glctx, textures_destroy);
+}
+
+static void backdrop_scale(AscBehavior *behavior) {
+    // scale the backdrop to the size of the window
+    if (!asc_active_window->resized) return;
+    asc_ptr_cast(AscSprite, sprite, behavior->node);
+    asc_vec2u window_size = asc_active_window->dimensions;
+    asc_sprite_set_size(sprite, window_size);
+}
+
+static void main_scene_frame_scale(AscBehavior *behavior) {
+    if (!asc_active_window->resized) return;
+    asc_ptr_cast(AscRectangle, frame, behavior->node);
+    asc_rectangle_set_bounds(frame, MAIN_SCENE->camera.viewport);
+}
+
+static void backdrop_create(void) {
+    const float scale = 1.f / asc_active_window->ui_scale;
+    AscSceneNode *node = asc_sprite(
+        .texture = TEXTURE_BACKDROP,
+        .texture_scale_mode = ASC_TEXTURE_SCALE_REPEAT,
+        .texture_scale_x = scale, .texture_scale_y = scale,
+    );
+    asc_behavior_add(node, .func = backdrop_scale);
+    asc_scene_add_node(BACKDROP_SCENE, node);
+
+    // also add a frame for the main scene
+    // add this to the UI layer so that the border size does not scale
+    AscSceneNode *frame = asc_rectangle(.thickness = 2, .color = ASC_RGBi(66, 142, 161));
+    asc_behavior_add(frame, .func = main_scene_frame_scale);
+    asc_ui_add_node(frame);
+}
+
+static void fps_counter_update(AscBehavior *behavior) {
+    asc_ptr_cast(AscText, node, behavior->node);
+    static float last_fps = 0.f;
+    if (fabsf(asc_context.frame_rate - last_fps) > 1) {
+        last_fps = asc_context.frame_rate;
+        asc_text_printf(node, "%.2f FPS", asc_context.frame_rate);
+    }
+}
+
+static void fps_counter_tie_to_corner(AscBehavior *behavior) {
+    // TODO: this should be replaced with some sort of UI layout manager
+    AscSceneNode *node = behavior->node;
+    if (asc_test_flag(node->flags, ASC_SCENE_NODE_GRAPHICS_UPDATED) || asc_active_window->resized) {
+        asc_scene_node_set_position2f(node, ASC_VEC2F(10,
+                asc_active_window->dimensions.y - ((AscText*)node)->dimension.height - 10
+        ));
+    }
+}
+
+static AscSceneNode *fps_counter_create(void) {
+    AscSceneNode *node = asc_text(
+        .name = "FPS Counter",
+        .color = ASC_RGB(1, 1, 1),
+        .font = asc_font(ASC_FONT_REGULAR, 12),
+    );
+    asc_behavior_add(node, .func = fps_counter_update, .interval = asc_seconds(1));
+    asc_behavior_add(node, fps_counter_tie_to_corner);
+    asc_ui_add_node(node);
+    return node;
+}
+
+static bool game_field_tile_chown(asc_vec2u coords, Player *player) {
+    unsigned x = coords.x, y = coords.y;
+    asc_ptr_cast(AscRectangle, tile, game.field->nodes[x][y]);
+    int old_owner = game.field->tile_data[x][y] & GAME_FIELD_TILE_OWNER_MASK;
+    if (player == NULL) {
+        asc_clear_flag(game.field->tile_data[x][y], GAME_FIELD_TILE_OWNER_MASK);
+        tile->color = ASC_RGBi(16, 50, 160);
+    } else {
+        asc_set_flag_masked(game.field->tile_data[x][y], GAME_FIELD_TILE_OWNER_MASK, player->number);
+        tile->color = player->color;
+    }
+    int new_owner = game.field->tile_data[x][y] & GAME_FIELD_TILE_OWNER_MASK;
+    return old_owner != new_owner;
+}
+
+static void game_field_create() {
+    // TODO: create a more interesting map than just a basic grid
+    AscSceneNode *node = asc_scene_node_empty();
+    game.field = asc_scene_node_allocate_data(node, sizeof(GameField));
+    for (unsigned x = 0; x < GAME_FIELD_SIZE; x++) {
+        for (unsigned y = 0; y < GAME_FIELD_SIZE; y++) {
+            AscSceneNode *tile = asc_rectangle(
+                .x = x*GAME_FIELD_TILE_SIZE, .y = y*GAME_FIELD_TILE_SIZE, .filled = true, .thickness = 2,
+                .width = GAME_FIELD_TILE_SIZE, .height = GAME_FIELD_TILE_SIZE,
+                .color = ASC_RGBi(16, 50, 160),
+                .border_color = ASC_RGBi(20, 84, 128),
+            );
+
+            game.field->tile_data[x][y] = GAME_FIELD_TILE_EXISTS_FLAG;
+            game.field->nodes[x][y] = tile;
+
+            asc_scene_node_link(node, tile);
+        }
+    }
+    asc_scene_node_set_zindex(node, -2);
+    asc_scene_add_node(MAIN_SCENE, node);
+}
+
+static asc_vec2u game_field_tile_at_position(asc_vec3f position) {
+    return ASC_VEC2U((int)position.x / GAME_FIELD_TILE_SIZE, (int)position.y / GAME_FIELD_TILE_SIZE);
+}
+
+typedef struct {
+    AscShaderProgram program;
+    asc_uniform_loc map_albedo;
+    asc_uniform_loc map_color;
+    asc_uniform_loc color;
+} PlayerShader;
+
+static void player_shader_init(AscShaderProgram *p, cx_attr_unused int flags) {
+    asc_shader_init_uniform_loc_nice(p, PlayerShader, map_albedo);
+    asc_shader_init_uniform_loc_nice(p, PlayerShader, map_color);
+    asc_shader_init_uniform_loc_nice(p, PlayerShader, color);
+}
+
+static AscShaderProgram *player_shader_create(cx_attr_unused int unused) {
+    return asc_shader_create((AscShaderCodes) {
+        .vtx = {.source_file = "sprite_vtx.glsl"},
+        .frag = {.source_file = "player.glsl",},
+    }, sizeof(PlayerShader), player_shader_init, 0);
+}
+
+static void player_draw(const AscCamera *camera, const AscSceneNode *node) {
+    asc_cptr_cast(AscSprite, sprite, node);
+    const Player *player = node->user_data;
+
+    // TODO: we shall finally add the shader information to the node
+    const AscShaderProgram *s = asc_shader_lookup(
+        SHADER_ID_PLAYER, player_shader_create, 0
+    );
+    if (asc_shader_use(s, camera)) return;
+    asc_cptr_cast(PlayerShader, shader, s);
+
+    asc_shader_upload_model_matrix(s, node);
+
+    // Bind texture
+    asc_texture_bind(TEXTURE_PLAYER, shader->map_albedo, 0);
+    asc_texture_bind(TEXTURE_PLAYER_COLOR_MAP, shader->map_color, 1);
+    asc_shader_upload_color(shader->color, player->color);
+    asc_mesh_draw_triangle_strip(&sprite->mesh);
+}
+
+static void player_set_health(Player *player, unsigned health) {
+    player->health = health;
+    // TODO: probably we want to add more effects when the health changes
+}
+
+static unsigned player_get_health(Player *player) {
+    return player->health;
+}
+
+static void player_move(AscBehavior *behavior) {
+    AscSceneNode *node = behavior->node;
+    Player *player = node->user_data;
+
+    // TODO: instead of skipping this behavior, it should be disabled when health is zero
+    if (player_get_health(player) == 0) return;
+
+    // TODO: move this to a different behavior
+    asc_scene_node_show(node);
+
+    const float ts = (float) GAME_FIELD_TILE_SIZE;
+
+    // check if the position is set programmatically
+    if (player->reset_position) {
+        asc_scene_node_set_position2f(node,
+            ASC_VEC2F(
+                ts * (player->new_position.x + .5f),
+                ts * (player->new_position.y + .5f)
+            ));
+        player->reset_position = false;
+        return;
+    }
+
+    // normal movement
+    const float speed = ts * player->speed * asc_context.frame_factor;
+    const asc_vec2i dir = directions[player->direction];
+    const asc_vec2f movement = asc_vec2f_scale(asc_vec2_itof(dir), speed);
+
+    // check if we are supposed to change the direction
+    if (player->direction == player->target_direction) {
+        // move without changing the direction
+        asc_scene_node_move2f(node, movement);
+    } else {
+        // determine axis
+        // and check if we are about to cross the center
+        // this relies on positive positions!
+        bool rotate = false;
+        if (movement.x == 0) {
+            // vertical movement
+            const float y_0 = floorf(node->position.y / ts);
+            const float y_curr = node->position.y / ts - y_0;
+            const float y_next = (node->position.y+movement.y) / ts - y_0;
+            const bool side_curr = y_curr > 0.5f;
+            const bool side_next = y_next > 0.5f;
+            rotate = side_curr ^ side_next;
+        } else {
+            // horizontal movement
+            const float x0 = floorf(node->position.x / ts);
+            const float x_curr = node->position.x / ts - x0;
+            const float x_next = (node->position.x+movement.x) / ts - x0;
+            const bool side_curr = x_curr > 0.5f;
+            const bool side_next = x_next > 0.5f;
+            rotate = side_curr ^ side_next;
+        }
+        if (rotate) {
+            // snap position to the center of the tile
+            asc_scene_node_set_position2f(node,
+            ASC_VEC2F(
+                (.5f+floorf(node->position.x / ts)) * ts,
+                (.5f+floorf(node->position.y / ts)) * ts
+            ));
+            player->direction = player->target_direction;
+            asc_scene_node_set_rotation(node, rotations[player->direction]);
+        } else {
+            // changing the direction not permitted, yet, continue movement
+            asc_scene_node_move2f(node, movement);
+        }
+    }
+
+    // die when leaving the game field
+    if (node->position.x < 0 || node->position.y < 0 ||
+        node->position.x > GAME_FIELD_SIZE*GAME_FIELD_TILE_SIZE ||
+        node->position.y > GAME_FIELD_SIZE*GAME_FIELD_TILE_SIZE) {
+        // TODO: add fancy death animation
+        asc_scene_node_hide(node);
+        player_set_health(player, 0);
+        // TODO: remove the trace gradually (dequeuing the trace should be a different behavior)
+        cxListClear(player->trace);
+        game.state = GAME_STATE_GAME_OVER;
+        return;
+    }
+
+    // TODO: collision detection
+
+    // update the trace, if necessary.
+    // remark: some calculations are repeated here, but they are cheap enough
+    {
+        const asc_vec2u tile_coords = game_field_tile_at_position(node->position);
+        // TODO: player should have been destroyed before leaving the field
+        if (tile_coords.x > GAME_FIELD_SIZE || tile_coords.y > GAME_FIELD_SIZE) return;
+        if (game_field_tile_chown(tile_coords, player)) {
+            // new owner of the tile!
+            asc_vec2u p = tile_coords;
+            cxListAdd(player->trace, &p);
+            if (cxListSize(player->trace) > 7) {
+                // TODO: implement power-up which makes the trace longer
+                cxListRemove(player->trace, 0);
+            }
+        }
+    }
+}
+
+static void player_controls(Player *player) {
+    if (asc_key_pressed(ASC_KEY(LEFT))) {
+        if (player->direction != MOVE_RIGHT) {
+            player->target_direction = MOVE_LEFT;
+        }
+    }
+    if (asc_key_pressed(ASC_KEY(RIGHT))) {
+        if (player->direction != MOVE_LEFT) {
+            player->target_direction = MOVE_RIGHT;
+        }
+    }
+    if (asc_key_pressed(ASC_KEY(UP))) {
+        if (player->direction != MOVE_DOWN) {
+            player->target_direction = MOVE_UP;
+        }
+    }
+    if (asc_key_pressed(ASC_KEY(DOWN))) {
+        if (player->direction != MOVE_UP) {
+            player->target_direction = MOVE_DOWN;
+        }
+    }
+}
+
+static void player_position(Player *pl, int x, int y) {
+    pl->new_position.x = x;
+    pl->new_position.y = y;
+    pl->reset_position = true;
+}
+
+static void player_destroy(CxAllocator *allocator, Player *player) {
+    cxListFree(player->trace);
+    cxFree(allocator, player);
+}
+
+static void player_trace_release_tile(asc_vec2u *coords) {
+    game_field_tile_chown(*coords, NULL);
+}
+
+static Player *player_create(void) {
+    AscSceneNode *node = asc_sprite(
+        .name = "Player",
+        .width = GAME_FIELD_TILE_SIZE,
+        .height = GAME_FIELD_TILE_SIZE,
+        .origin_x = GAME_FIELD_TILE_SIZE / 2,
+        .origin_y = GAME_FIELD_TILE_SIZE / 2,
+    );
+    asc_scene_add_node(MAIN_SCENE, node);
+    Player *player = asc_scene_node_allocate_data(node, sizeof(Player));
+    player_position(player, 12, 8);
+    player->speed = 3.f; // start with 3 tiles/sec
+    player->number = 1;
+    player->health = 100;
+    player->color = ASC_RGB(1, 0, 0);
+    player->trace = cxLinkedListCreateSimple(sizeof(asc_vec2u));
+    cxDefineDestructor(player->trace, player_trace_release_tile);
+    node->draw_func = player_draw;
+    node->user_data_free_func = (cx_destructor_func2)player_destroy;
+    asc_behavior_add(node, player_move);
+    return player;
+}
+
+static asc_rect main_scene_viewport_update(asc_vec2u window_size) {
+
+    // margins
+    const unsigned margin = 16;
+
+    // space for score, power-ups, etc.
+    const unsigned left_area = (unsigned) (asc_active_window->ui_scale*HUD_WIDTH);
+
+    // calculate how many pixels need to be removed from width and height
+    const unsigned rw = 2*margin + left_area;
+    const unsigned rh = 2*margin;
+
+    // check if there is still a viewport left and chicken out when not
+    if (window_size.width < rw || window_size.height < rh) {
+        return ASC_RECT(0, 0, 0, 0);
+    }
+    window_size.width -= rw;
+    window_size.height -= rh;
+
+    // Compute scaling and offsets
+    unsigned viewport_size, offset_x = 0, offset_y = 0;
+    if (window_size.width > window_size.height) {
+        // Wider window: letterbox (black bars on top/bottom)
+        offset_x = (window_size.width - window_size.height) / 2;
+        viewport_size = window_size.height;
+    } else {
+        // Taller window: pillarbox (black bars on sides)
+        offset_y = (window_size.height - window_size.width) / 2;
+        viewport_size = window_size.width;
+    }
+    offset_x += left_area + margin;
+    offset_y += margin;
+
+    // Set the viewport to the scaled and centered region
+    return ASC_RECT(offset_x, offset_y, viewport_size, viewport_size);
+}
+
+int main(void) {
+    asc_context_initialize();
+    if (asc_has_error()) {
+        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR,
+                "Fatal Error",asc_get_error(), NULL);
+        return 1;
+    }
+
+    // initialize globals
+    globals_init();
+
+    // create the window
+    asc_window_initialize(0, asc_gl_context_settings_default(4, 0));
+    asc_window_set_title(0, "Snake");
+    asc_window_set_size(0, asc_vec2_ftou(
+        asc_vec2f_scale(ASC_VEC2F(1000+HUD_WIDTH, 1000), asc_ui_scale_auto())));
+    asc_window_center(0);
+
+    // load textures
+    textures_init();
+
+    // initialize backdrop scene
+    asc_scene_init(BACKDROP_SCENE, "backdrop",
+        .type = ASC_CAMERA_ORTHO,
+        .projection_update_func = asc_camera_ortho_update_size
+    );
+    backdrop_create();
+
+    // Initialize main scene
+    asc_scene_init(MAIN_SCENE, "main",
+        .type = ASC_CAMERA_ORTHO,
+        .ortho.rect = ASC_RECT(
+            -GAME_FIELD_TILE_SIZE,
+            -GAME_FIELD_TILE_SIZE,
+            (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE,
+            (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE
+        ),
+        .viewport_clear = true,
+        .clear_color = ASC_RGBi(0, 32, 16),
+        .viewport_update_func = main_scene_viewport_update
+    );
+
+    // create the fps counter
+    AscSceneNode *fps_counter = fps_counter_create();
+    asc_scene_node_hide(fps_counter);
+
+    // create game over text
+    AscSceneNode *text_game_over = asc_text(
+        .name = "game_over_text",
+        .text = "Game Over\nPress R to Restart",
+        .color = ASC_RGB(1, 1, 1),
+        .font = asc_font(ASC_FONT_REGULAR, 36),
+        .alignment = ASC_TEXT_ALIGN_CENTER,
+        .centered = true,
+        .x = (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE/2,
+        .y = (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE/2 - 60,
+    );
+    asc_scene_node_hide(text_game_over);
+    // TODO: add as a UI node and add a behavior which centers the node in the main scenes viewport
+    //       otherwise we won't be able to implement a moving camera in the future
+    asc_scene_add_node(MAIN_SCENE, text_game_over);
+
+    // initialize the game state
+    // TODO: add a main menu and start with the menu
+    game.state = GAME_STATE_PLAYING;
+    game.players[0] = player_create();
+    game_field_create();
+
+    // Main Loop
+    do {
+        // quit application on any error
+        if (asc_has_error()) {
+            SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR,
+                    "Fatal Error", asc_get_error(),
+                    asc_active_window->window);
+            asc_clear_error();
+            asc_context_quit();
+        }
+
+        // game states
+        // TODO: move all this into behaviors
+        if (game.state == GAME_STATE_PLAYING) {
+            // TODO: implement hot seat 1on1 multiplayer
+            player_controls(game.players[0]);
+        } else if (game.state == GAME_STATE_GAME_OVER) {
+            asc_scene_node_show(text_game_over);
+            if (asc_key_pressed(ASC_KEY(R))) {
+                // TODO: re-load the "level"
+                player_position(game.players[0], 12, 8);
+                player_set_health(game.players[0], 100);
+                game.state = GAME_STATE_PLAYING;
+                asc_scene_node_hide(text_game_over);
+            }
+        }
+
+        // debug-key for clearing the shader registry
+        if (asc_key_pressed(ASC_KEY(S))) {
+            asc_shader_clear_registry();
+            asc_dprintf("Shader cache cleared.");
+        }
+
+        // show/hide the FPS counter
+        if (asc_key_pressed(ASC_KEY(F2))) {
+            asc_scene_node_toggle_visibility(fps_counter);
+        }
+
+        // quit application on ESC key press
+        if (asc_key_pressed(ASC_KEY(ESCAPE))) {
+            asc_context_quit();
+        }
+    } while (asc_loop_next());
+
+    // cleanup
+    asc_context_destroy();
+    return 0;
+}
+

Binary file demo/snake/textures/backdrop.png has changed

Binary file demo/snake/textures/player-color-map.png has changed

Binary file demo/snake/textures/player.png has changed

--- a/test/snake/Makefile	Mon Aug 18 23:11:50 2025 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,65 +0,0 @@
-# Copyright 2023 Mike Becker. All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are met:
-#
-#   1. Redistributions of source code must retain the above copyright
-#      notice, this list of conditions and the following disclaimer.
-#
-#   2. Redistributions in binary form must reproduce the above copyright
-#      notice, this list of conditions and the following disclaimer in the
-#      documentation and/or other materials provided with the distribution.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
-# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-# POSSIBILITY OF SUCH DAMAGE.
-#
-
-include ../../config.mk
-
-BUILD_DIR=$(srcdir)/build/snake
-LIB_ASCENSION=$(srcdir)/build/lib/libascension.a
-CFLAGS += -I$(srcdir)/src $(CPPFLAGS)
-
-all: $(BUILD_DIR) $(BUILD_DIR)/snake FORCE
-	@echo "Demo game 'snake' successfully built."
-	@cp -Ruf $(srcdir)/shader $(BUILD_DIR)/
-	@cp -Ruf $(srcdir)/fonts $(BUILD_DIR)/
-	@cp -Ruf textures $(BUILD_DIR)/
-	@cp -Ruf shader $(BUILD_DIR)/
-	@echo "Assets for demo game 'snake' successfully copied."
-
-$(BUILD_DIR):
-	mkdir -p $@
-
-$(BUILD_DIR)/snake: $(BUILD_DIR)/snake.o $(LIB_ASCENSION)
-	@echo "Linking snake..."
-	$(CC) $(LDFLAGS) -o $@ $^
-
-$(LIB_ASCENSION):
-	test -f "$@"
-
-FORCE:
-
-$(BUILD_DIR)/snake.o: snake.c ../../src/ascension/core.h \
- ../../src/ascension/error.h ../../src/ascension/context.h \
- ../../src/ascension/datatypes.h ../../src/ascension/window.h \
- ../../src/ascension/glcontext.h ../../src/ascension/scene.h \
- ../../src/ascension/scene_node.h ../../src/ascension/transform.h \
- ../../src/ascension/camera.h ../../src/ascension/input.h \
- ../../src/ascension/behavior.h ../../src/ascension/ui.h \
- ../../src/ascension/text.h ../../src/ascension/font.h \
- ../../src/ascension/mesh.h ../../src/ascension/texture.h \
- ../../src/ascension/sprite.h ../../src/ascension/2d.h \
- ../../src/ascension/shader.h
-	@echo "Compiling $<"
-	$(CC) -o $@ $(CFLAGS) -c $<
-

--- a/test/snake/shader/player.glsl	Mon Aug 18 23:11:50 2025 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,16 +0,0 @@
-layout(location = 0) out vec4 diffuse;
-in vec2 uvcoord;
-
-uniform sampler2D map_albedo;
-uniform sampler2D map_color;
-uniform vec4 color;
-
-void main(void) {
-    // TODO: use greyscale texture instead
-    vec4 color_map_pixel = texture(map_color, uvcoord);
-    if (color_map_pixel.a > 0) {
-        diffuse = color * color_map_pixel * texture(map_albedo, uvcoord);
-    } else {
-        diffuse = texture(map_albedo, uvcoord);
-    }
-}

--- a/test/snake/snake.c	Mon Aug 18 23:11:50 2025 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,598 +0,0 @@
-/*
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
- * Copyright 2023 Mike Becker. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *   1. Redistributions of source code must retain the above copyright
- *      notice, this list of conditions and the following disclaimer.
- *
- *   2. Redistributions in binary form must reproduce the above copyright
- *      notice, this list of conditions and the following disclaimer in the
- *      documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <ascension/core.h>
-#include <ascension/ui.h>
-#include <ascension/sprite.h>
-#include <ascension/2d.h>
-#include <ascension/shader.h>
-
-#include <cx/printf.h>
-#include <cx/linked_list.h>
-
-#define TEXTURE_2D_COUNT 3
-static AscTexture tex2d[TEXTURE_2D_COUNT];
-#define TEXTURE_PLAYER &tex2d[0]
-#define TEXTURE_PLAYER_COLOR_MAP &tex2d[1]
-#define TEXTURE_BACKDROP &tex2d[2]
-
-#define SHADER_ID_PLAYER 1
-
-#define BACKDROP_SCENE asc_window_scene(0)
-#define MAIN_SCENE asc_window_scene(1)
-#define HUD_WIDTH 400
-
-enum MoveDirection {
-    MOVE_UP,
-    MOVE_LEFT,
-    MOVE_DOWN,
-    MOVE_RIGHT
-};
-
-static asc_transform rotations[4];
-static asc_vec2i directions[4];
-
-typedef struct {
-    asc_color color;
-    enum MoveDirection direction;
-    enum MoveDirection target_direction;
-    /**
-     * The speed in tiles per second.
-     */
-    float speed;
-    /**
-     * A linked list of vec2u elements describing the current trace.
-     */
-    CxList *trace;
-    /**
-     * The new position of the player when @c reset_position is @c true.
-     */
-    asc_vec2i new_position;
-    unsigned health;
-    bool reset_position;
-    uint8_t number;
-} Player;
-
-#define GAME_FIELD_SIZE 32
-#define GAME_FIELD_TILE_SIZE 32
-
-/** The bit in the tile data indicating if the tile exists. */
-#define GAME_FIELD_TILE_EXISTS_FLAG  0x80
-/** The bits in the tile data that identify the owner. */
-#define GAME_FIELD_TILE_OWNER_MASK   0xF
-
-typedef struct {
-    AscSceneNode *nodes[GAME_FIELD_SIZE][GAME_FIELD_SIZE];
-    int8_t tile_data[GAME_FIELD_SIZE][GAME_FIELD_SIZE];
-} GameField;
-
-
-#define GAME_STATE_MENU 0
-#define GAME_STATE_PLAYING 1
-#define GAME_STATE_GAME_OVER 2
-
-typedef struct {
-    int state;
-    GameField *field;
-    Player *players[4];
-} GameState;
-
-GameState game = {0};
-
-static void globals_init(void) {
-    asc_transform_identity(rotations[MOVE_UP]);
-    asc_transform_roll(rotations[MOVE_LEFT], asc_rad(-90));
-    asc_transform_roll(rotations[MOVE_RIGHT], asc_rad(90));
-    asc_transform_roll(rotations[MOVE_DOWN], asc_rad(180));
-    directions[MOVE_UP] = ASC_VEC2I(0, -1);
-    directions[MOVE_LEFT] = ASC_VEC2I(-1, 0);
-    directions[MOVE_DOWN] = ASC_VEC2I(0, 1);
-    directions[MOVE_RIGHT] = ASC_VEC2I(1, 0);
-}
-
-static void textures_destroy(void) {
-    asc_texture_destroy(tex2d, TEXTURE_2D_COUNT);
-}
-
-static void textures_init(void) {
-    asc_texture_init_2d(tex2d, TEXTURE_2D_COUNT);
-    asc_texture_from_file(TEXTURE_PLAYER, "player.png");
-    asc_texture_from_file(TEXTURE_PLAYER_COLOR_MAP, "player-color-map.png");
-    asc_texture_from_file(TEXTURE_BACKDROP, "backdrop.png");
-    asc_gl_context_add_cleanup_func(asc_active_glctx, textures_destroy);
-}
-
-static void backdrop_scale(AscBehavior *behavior) {
-    // scale the backdrop to the size of the window
-    if (!asc_active_window->resized) return;
-    asc_ptr_cast(AscSprite, sprite, behavior->node);
-    asc_vec2u window_size = asc_active_window->dimensions;
-    asc_sprite_set_size(sprite, window_size);
-}
-
-static void main_scene_frame_scale(AscBehavior *behavior) {
-    if (!asc_active_window->resized) return;
-    asc_ptr_cast(AscRectangle, frame, behavior->node);
-    asc_rectangle_set_bounds(frame, MAIN_SCENE->camera.viewport);
-}
-
-static void backdrop_create(void) {
-    const float scale = 1.f / asc_active_window->ui_scale;
-    AscSceneNode *node = asc_sprite(
-        .texture = TEXTURE_BACKDROP,
-        .texture_scale_mode = ASC_TEXTURE_SCALE_REPEAT,
-        .texture_scale_x = scale, .texture_scale_y = scale,
-    );
-    asc_behavior_add(node, .func = backdrop_scale);
-    asc_scene_add_node(BACKDROP_SCENE, node);
-
-    // also add a frame for the main scene
-    // add this to the UI layer so that the border size does not scale
-    AscSceneNode *frame = asc_rectangle(.thickness = 2, .color = ASC_RGBi(66, 142, 161));
-    asc_behavior_add(frame, .func = main_scene_frame_scale);
-    asc_ui_add_node(frame);
-}
-
-static void fps_counter_update(AscBehavior *behavior) {
-    asc_ptr_cast(AscText, node, behavior->node);
-    static float last_fps = 0.f;
-    if (fabsf(asc_context.frame_rate - last_fps) > 1) {
-        last_fps = asc_context.frame_rate;
-        asc_text_printf(node, "%.2f FPS", asc_context.frame_rate);
-    }
-}
-
-static void fps_counter_tie_to_corner(AscBehavior *behavior) {
-    // TODO: this should be replaced with some sort of UI layout manager
-    AscSceneNode *node = behavior->node;
-    if (asc_test_flag(node->flags, ASC_SCENE_NODE_GRAPHICS_UPDATED) || asc_active_window->resized) {
-        asc_scene_node_set_position2f(node, ASC_VEC2F(10,
-                asc_active_window->dimensions.y - ((AscText*)node)->dimension.height - 10
-        ));
-    }
-}
-
-static AscSceneNode *fps_counter_create(void) {
-    AscSceneNode *node = asc_text(
-        .name = "FPS Counter",
-        .color = ASC_RGB(1, 1, 1),
-        .font = asc_font(ASC_FONT_REGULAR, 12),
-    );
-    asc_behavior_add(node, .func = fps_counter_update, .interval = asc_seconds(1));
-    asc_behavior_add(node, fps_counter_tie_to_corner);
-    asc_ui_add_node(node);
-    return node;
-}
-
-static bool game_field_tile_chown(asc_vec2u coords, Player *player) {
-    unsigned x = coords.x, y = coords.y;
-    asc_ptr_cast(AscRectangle, tile, game.field->nodes[x][y]);
-    int old_owner = game.field->tile_data[x][y] & GAME_FIELD_TILE_OWNER_MASK;
-    if (player == NULL) {
-        asc_clear_flag(game.field->tile_data[x][y], GAME_FIELD_TILE_OWNER_MASK);
-        tile->color = ASC_RGBi(16, 50, 160);
-    } else {
-        asc_set_flag_masked(game.field->tile_data[x][y], GAME_FIELD_TILE_OWNER_MASK, player->number);
-        tile->color = player->color;
-    }
-    int new_owner = game.field->tile_data[x][y] & GAME_FIELD_TILE_OWNER_MASK;
-    return old_owner != new_owner;
-}
-
-static void game_field_create() {
-    // TODO: create a more interesting map than just a basic grid
-    AscSceneNode *node = asc_scene_node_empty();
-    game.field = asc_scene_node_allocate_data(node, sizeof(GameField));
-    for (unsigned x = 0; x < GAME_FIELD_SIZE; x++) {
-        for (unsigned y = 0; y < GAME_FIELD_SIZE; y++) {
-            AscSceneNode *tile = asc_rectangle(
-                .x = x*GAME_FIELD_TILE_SIZE, .y = y*GAME_FIELD_TILE_SIZE, .filled = true, .thickness = 2,
-                .width = GAME_FIELD_TILE_SIZE, .height = GAME_FIELD_TILE_SIZE,
-                .color = ASC_RGBi(16, 50, 160),
-                .border_color = ASC_RGBi(20, 84, 128),
-            );
-
-            game.field->tile_data[x][y] = GAME_FIELD_TILE_EXISTS_FLAG;
-            game.field->nodes[x][y] = tile;
-
-            asc_scene_node_link(node, tile);
-        }
-    }
-    asc_scene_node_set_zindex(node, -2);
-    asc_scene_add_node(MAIN_SCENE, node);
-}
-
-static asc_vec2u game_field_tile_at_position(asc_vec3f position) {
-    return ASC_VEC2U((int)position.x / GAME_FIELD_TILE_SIZE, (int)position.y / GAME_FIELD_TILE_SIZE);
-}
-
-typedef struct {
-    AscShaderProgram program;
-    asc_uniform_loc map_albedo;
-    asc_uniform_loc map_color;
-    asc_uniform_loc color;
-} PlayerShader;
-
-static void player_shader_init(AscShaderProgram *p, cx_attr_unused int flags) {
-    asc_shader_init_uniform_loc_nice(p, PlayerShader, map_albedo);
-    asc_shader_init_uniform_loc_nice(p, PlayerShader, map_color);
-    asc_shader_init_uniform_loc_nice(p, PlayerShader, color);
-}
-
-static AscShaderProgram *player_shader_create(cx_attr_unused int unused) {
-    return asc_shader_create((AscShaderCodes) {
-        .vtx = {.source_file = "sprite_vtx.glsl"},
-        .frag = {.source_file = "player.glsl",},
-    }, sizeof(PlayerShader), player_shader_init, 0);
-}
-
-static void player_draw(const AscCamera *camera, const AscSceneNode *node) {
-    asc_cptr_cast(AscSprite, sprite, node);
-    const Player *player = node->user_data;
-
-    // TODO: we shall finally add the shader information to the node
-    const AscShaderProgram *s = asc_shader_lookup(
-        SHADER_ID_PLAYER, player_shader_create, 0
-    );
-    if (asc_shader_use(s, camera)) return;
-    asc_cptr_cast(PlayerShader, shader, s);
-
-    asc_shader_upload_model_matrix(s, node);
-
-    // Bind texture
-    asc_texture_bind(TEXTURE_PLAYER, shader->map_albedo, 0);
-    asc_texture_bind(TEXTURE_PLAYER_COLOR_MAP, shader->map_color, 1);
-    asc_shader_upload_color(shader->color, player->color);
-    asc_mesh_draw_triangle_strip(&sprite->mesh);
-}
-
-static void player_set_health(Player *player, unsigned health) {
-    player->health = health;
-    // TODO: probably we want to add more effects when the health changes
-}
-
-static unsigned player_get_health(Player *player) {
-    return player->health;
-}
-
-static void player_move(AscBehavior *behavior) {
-    AscSceneNode *node = behavior->node;
-    Player *player = node->user_data;
-
-    // TODO: instead of skipping this behavior, it should be disabled when health is zero
-    if (player_get_health(player) == 0) return;
-
-    // TODO: move this to a different behavior
-    asc_scene_node_show(node);
-
-    const float ts = (float) GAME_FIELD_TILE_SIZE;
-
-    // check if the position is set programmatically
-    if (player->reset_position) {
-        asc_scene_node_set_position2f(node,
-            ASC_VEC2F(
-                ts * (player->new_position.x + .5f),
-                ts * (player->new_position.y + .5f)
-            ));
-        player->reset_position = false;
-        return;
-    }
-
-    // normal movement
-    const float speed = ts * player->speed * asc_context.frame_factor;
-    const asc_vec2i dir = directions[player->direction];
-    const asc_vec2f movement = asc_vec2f_scale(asc_vec2_itof(dir), speed);
-
-    // check if we are supposed to change the direction
-    if (player->direction == player->target_direction) {
-        // move without changing the direction
-        asc_scene_node_move2f(node, movement);
-    } else {
-        // determine axis
-        // and check if we are about to cross the center
-        // this relies on positive positions!
-        bool rotate = false;
-        if (movement.x == 0) {
-            // vertical movement
-            const float y_0 = floorf(node->position.y / ts);
-            const float y_curr = node->position.y / ts - y_0;
-            const float y_next = (node->position.y+movement.y) / ts - y_0;
-            const bool side_curr = y_curr > 0.5f;
-            const bool side_next = y_next > 0.5f;
-            rotate = side_curr ^ side_next;
-        } else {
-            // horizontal movement
-            const float x0 = floorf(node->position.x / ts);
-            const float x_curr = node->position.x / ts - x0;
-            const float x_next = (node->position.x+movement.x) / ts - x0;
-            const bool side_curr = x_curr > 0.5f;
-            const bool side_next = x_next > 0.5f;
-            rotate = side_curr ^ side_next;
-        }
-        if (rotate) {
-            // snap position to the center of the tile
-            asc_scene_node_set_position2f(node,
-            ASC_VEC2F(
-                (.5f+floorf(node->position.x / ts)) * ts,
-                (.5f+floorf(node->position.y / ts)) * ts
-            ));
-            player->direction = player->target_direction;
-            asc_scene_node_set_rotation(node, rotations[player->direction]);
-        } else {
-            // changing the direction not permitted, yet, continue movement
-            asc_scene_node_move2f(node, movement);
-        }
-    }
-
-    // die when leaving the game field
-    if (node->position.x < 0 || node->position.y < 0 ||
-        node->position.x > GAME_FIELD_SIZE*GAME_FIELD_TILE_SIZE ||
-        node->position.y > GAME_FIELD_SIZE*GAME_FIELD_TILE_SIZE) {
-        // TODO: add fancy death animation
-        asc_scene_node_hide(node);
-        player_set_health(player, 0);
-        // TODO: remove the trace gradually (dequeuing the trace should be a different behavior)
-        cxListClear(player->trace);
-        game.state = GAME_STATE_GAME_OVER;
-        return;
-    }
-
-    // TODO: collision detection
-
-    // update the trace, if necessary.
-    // remark: some calculations are repeated here, but they are cheap enough
-    {
-        const asc_vec2u tile_coords = game_field_tile_at_position(node->position);
-        // TODO: player should have been destroyed before leaving the field
-        if (tile_coords.x > GAME_FIELD_SIZE || tile_coords.y > GAME_FIELD_SIZE) return;
-        if (game_field_tile_chown(tile_coords, player)) {
-            // new owner of the tile!
-            asc_vec2u p = tile_coords;
-            cxListAdd(player->trace, &p);
-            if (cxListSize(player->trace) > 7) {
-                // TODO: implement power-up which makes the trace longer
-                cxListRemove(player->trace, 0);
-            }
-        }
-    }
-}
-
-static void player_controls(Player *player) {
-    if (asc_key_pressed(ASC_KEY(LEFT))) {
-        if (player->direction != MOVE_RIGHT) {
-            player->target_direction = MOVE_LEFT;
-        }
-    }
-    if (asc_key_pressed(ASC_KEY(RIGHT))) {
-        if (player->direction != MOVE_LEFT) {
-            player->target_direction = MOVE_RIGHT;
-        }
-    }
-    if (asc_key_pressed(ASC_KEY(UP))) {
-        if (player->direction != MOVE_DOWN) {
-            player->target_direction = MOVE_UP;
-        }
-    }
-    if (asc_key_pressed(ASC_KEY(DOWN))) {
-        if (player->direction != MOVE_UP) {
-            player->target_direction = MOVE_DOWN;
-        }
-    }
-}
-
-static void player_position(Player *pl, int x, int y) {
-    pl->new_position.x = x;
-    pl->new_position.y = y;
-    pl->reset_position = true;
-}
-
-static void player_destroy(CxAllocator *allocator, Player *player) {
-    cxListFree(player->trace);
-    cxFree(allocator, player);
-}
-
-static void player_trace_release_tile(asc_vec2u *coords) {
-    game_field_tile_chown(*coords, NULL);
-}
-
-static Player *player_create(void) {
-    AscSceneNode *node = asc_sprite(
-        .name = "Player",
-        .width = GAME_FIELD_TILE_SIZE,
-        .height = GAME_FIELD_TILE_SIZE,
-        .origin_x = GAME_FIELD_TILE_SIZE / 2,
-        .origin_y = GAME_FIELD_TILE_SIZE / 2,
-    );
-    asc_scene_add_node(MAIN_SCENE, node);
-    Player *player = asc_scene_node_allocate_data(node, sizeof(Player));
-    player_position(player, 12, 8);
-    player->speed = 3.f; // start with 3 tiles/sec
-    player->number = 1;
-    player->health = 100;
-    player->color = ASC_RGB(1, 0, 0);
-    player->trace = cxLinkedListCreateSimple(sizeof(asc_vec2u));
-    cxDefineDestructor(player->trace, player_trace_release_tile);
-    node->draw_func = player_draw;
-    node->user_data_free_func = (cx_destructor_func2)player_destroy;
-    asc_behavior_add(node, player_move);
-    return player;
-}
-
-static asc_rect main_scene_viewport_update(asc_vec2u window_size) {
-
-    // margins
-    const unsigned margin = 16;
-
-    // space for score, power-ups, etc.
-    const unsigned left_area = (unsigned) (asc_active_window->ui_scale*HUD_WIDTH);
-
-    // calculate how many pixels need to be removed from width and height
-    const unsigned rw = 2*margin + left_area;
-    const unsigned rh = 2*margin;
-
-    // check if there is still a viewport left and chicken out when not
-    if (window_size.width < rw || window_size.height < rh) {
-        return ASC_RECT(0, 0, 0, 0);
-    }
-    window_size.width -= rw;
-    window_size.height -= rh;
-
-    // Compute scaling and offsets
-    unsigned viewport_size, offset_x = 0, offset_y = 0;
-    if (window_size.width > window_size.height) {
-        // Wider window: letterbox (black bars on top/bottom)
-        offset_x = (window_size.width - window_size.height) / 2;
-        viewport_size = window_size.height;
-    } else {
-        // Taller window: pillarbox (black bars on sides)
-        offset_y = (window_size.height - window_size.width) / 2;
-        viewport_size = window_size.width;
-    }
-    offset_x += left_area + margin;
-    offset_y += margin;
-
-    // Set the viewport to the scaled and centered region
-    return ASC_RECT(offset_x, offset_y, viewport_size, viewport_size);
-}
-
-int main(void) {
-    asc_context_initialize();
-    if (asc_has_error()) {
-        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR,
-                "Fatal Error",asc_get_error(), NULL);
-        return 1;
-    }
-
-    // initialize globals
-    globals_init();
-
-    // create the window
-    asc_window_initialize(0, asc_gl_context_settings_default(4, 0));
-    asc_window_set_title(0, "Snake");
-    asc_window_set_size(0, asc_vec2_ftou(
-        asc_vec2f_scale(ASC_VEC2F(1000+HUD_WIDTH, 1000), asc_ui_scale_auto())));
-    asc_window_center(0);
-
-    // load textures
-    textures_init();
-
-    // initialize backdrop scene
-    asc_scene_init(BACKDROP_SCENE, "backdrop",
-        .type = ASC_CAMERA_ORTHO,
-        .projection_update_func = asc_camera_ortho_update_size
-    );
-    backdrop_create();
-
-    // Initialize main scene
-    asc_scene_init(MAIN_SCENE, "main",
-        .type = ASC_CAMERA_ORTHO,
-        .ortho.rect = ASC_RECT(
-            -GAME_FIELD_TILE_SIZE,
-            -GAME_FIELD_TILE_SIZE,
-            (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE,
-            (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE
-        ),
-        .viewport_clear = true,
-        .clear_color = ASC_RGBi(0, 32, 16),
-        .viewport_update_func = main_scene_viewport_update
-    );
-
-    // create the fps counter
-    AscSceneNode *fps_counter = fps_counter_create();
-    asc_scene_node_hide(fps_counter);
-
-    // create game over text
-    AscSceneNode *text_game_over = asc_text(
-        .name = "game_over_text",
-        .text = "Game Over\nPress R to Restart",
-        .color = ASC_RGB(1, 1, 1),
-        .font = asc_font(ASC_FONT_REGULAR, 36),
-        .alignment = ASC_TEXT_ALIGN_CENTER,
-        .centered = true,
-        .x = (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE/2,
-        .y = (GAME_FIELD_SIZE+2)*GAME_FIELD_TILE_SIZE/2 - 60,
-    );
-    asc_scene_node_hide(text_game_over);
-    // TODO: add as a UI node and add a behavior which centers the node in the main scenes viewport
-    //       otherwise we won't be able to implement a moving camera in the future
-    asc_scene_add_node(MAIN_SCENE, text_game_over);
-
-    // initialize the game state
-    // TODO: add a main menu and start with the menu
-    game.state = GAME_STATE_PLAYING;
-    game.players[0] = player_create();
-    game_field_create();
-
-    // Main Loop
-    do {
-        // quit application on any error
-        if (asc_has_error()) {
-            SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR,
-                    "Fatal Error", asc_get_error(),
-                    asc_active_window->window);
-            asc_clear_error();
-            asc_context_quit();
-        }
-
-        // game states
-        // TODO: move all this into behaviors
-        if (game.state == GAME_STATE_PLAYING) {
-            // TODO: implement hot seat 1on1 multiplayer
-            player_controls(game.players[0]);
-        } else if (game.state == GAME_STATE_GAME_OVER) {
-            asc_scene_node_show(text_game_over);
-            if (asc_key_pressed(ASC_KEY(R))) {
-                // TODO: re-load the "level"
-                player_position(game.players[0], 12, 8);
-                player_set_health(game.players[0], 100);
-                game.state = GAME_STATE_PLAYING;
-                asc_scene_node_hide(text_game_over);
-            }
-        }
-
-        // debug-key for clearing the shader registry
-        if (asc_key_pressed(ASC_KEY(S))) {
-            asc_shader_clear_registry();
-            asc_dprintf("Shader cache cleared.");
-        }
-
-        // show/hide the FPS counter
-        if (asc_key_pressed(ASC_KEY(F2))) {
-            asc_scene_node_toggle_visibility(fps_counter);
-        }
-
-        // quit application on ESC key press
-        if (asc_key_pressed(ASC_KEY(ESCAPE))) {
-            asc_context_quit();
-        }
-    } while (asc_loop_next());
-
-    // cleanup
-    asc_context_destroy();
-    return 0;
-}
-

Binary file test/snake/textures/backdrop.png has changed

Binary file test/snake/textures/player-color-map.png has changed

Binary file test/snake/textures/player.png has changed