twn_draw.c: draw_camera_2d()!

apps/demos/platformer/scenes/ingame.c

@@ -18,6 +18,11 @@ static void ingame_tick(State *state) {
     input_action("player_jump", "SPACE");
     input_action("player_run", "LSHIFT");
 
+    draw_camera_2d((Vec2){ scn->player->rect.x + scn->player->rect.w / 2 - ctx.resolution.x / 2,
+                           scn->player->rect.y + scn->player->rect.h / 2 - ctx.resolution.y / 2 },
+        0, 1
+    );
+
     world_drawdef(scn->world);
     player_calc(scn->player);
 }

include/twn_draw.h

@@ -81,6 +81,10 @@ TWN_API void draw_billboard(const char *texture,
                             Color color,        /* optional, default: all 255 */
                             bool cylindrical);  /* optional, default: false */
 
+TWN_API void draw_camera_2d(Vec2 position,      /* optional, default: (0, 0) */
+                            float rotation,     /* optional, default: 0 */
+                            float zoom);        /* optional, default: 1 */
+
 /* sets a perspective 3d camera to be used for all 3d commands */
 /* fov = 0 corresponds to orthographic projection */
 TWN_API void draw_camera(Vec3 position,

share/twn_api.json

@@ -185,6 +185,17 @@
             ]
         },
 
+        "draw_camera_2d": {
+            "module": "draw",
+            "symbol": "camera_2d",
+            "header": "twn_draw.h",
+            "params": [
+                { "name": "position", "type": "Vec2", "default": { "x": 0, "y": 0 } },
+                { "name": "rotation", "type": "float", "default": 0 },
+                { "name": "zoom", "type": "float", "default": 1 }
+            ]
+        },
+
         "draw_camera": {
             "module": "draw",
             "symbol": "camera",

src/rendering/twn_draw.c

@@ -17,19 +17,30 @@
 
 DeferredCommand *deferred_commands;
 
-/* TODO: have a default initialized one */
 /* TODO: with buffered render, don't we use camera of wrong frame right now ? */
 Matrix4 camera_projection_matrix;
 Matrix4 camera_look_at_matrix;
 
+float camera_2d_rotation;
+Vec2 camera_2d_position;
+float camera_2d_zoom;
+
 double depth_range_low, depth_range_high;
 
 
+static void reset_camera_2d(void) {
+    camera_2d_position = (Vec2){0};
+    camera_2d_zoom = 1;
+    camera_2d_rotation = 0;
+}
+
+
 void render_clear(void) {
     draw_camera((Vec3){0, 0, 0}, (Vec3){0, 0, 1}, (Vec3){0, 1, 0}, 1.57079632679f, 1);
+    reset_camera_2d();
 
     text_cache_reset_arena(&ctx.text_cache);
-    
+
     /* since i don't intend to free the queues, */
     /* it's faster and simpler to just "start over" */
     /* and start overwriting the existing data */
@@ -415,6 +426,22 @@ void render(void) {
 }
 
 
+/* TODO: check for NaNs and alike */
+TWN_API void draw_camera_2d(Vec2 position,
+                            float rotation,
+                            float zoom)
+{
+    if (zoom <= 0) {
+        log_warn("Invalid zoom value given to draw_camera_2d()");
+        zoom = 0.1f;
+    }
+
+    camera_2d_position = position;
+    camera_2d_rotation = rotation;
+    camera_2d_zoom = zoom;
+}
+
+/* TODO: check for NaNs and alike */
 void draw_camera(Vec3 position, Vec3 direction, Vec3 up, float fov, float zoom) {
     bool const orthographic = fabsf(0.0f - fov) < 0.00001f;
     if (!orthographic && fov >= (float)(M_PI))
@@ -441,6 +468,8 @@ void draw_camera(Vec3 position, Vec3 direction, Vec3 up, float fov, float zoom)
 
 
 /* TODO: https://stackoverflow.com/questions/62493770/how-to-add-roll-in-camera-class */
+/* TODO: check for NaNs and alike */
+/* TODOL call draw_camera() instead, to reuse the code */
 DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position,
                                                                   float roll,
                                                                   float pitch,

src/rendering/twn_draw_c.h

@@ -17,6 +17,10 @@
 extern Matrix4 camera_projection_matrix;
 extern Matrix4 camera_look_at_matrix;
 
+extern float camera_2d_rotation;
+extern Vec2 camera_2d_position;
+extern float camera_2d_zoom;
+
 extern double depth_range_low, depth_range_high;
 
 #define QUAD_ELEMENT_BUFFER_LENGTH (65536 / 6)

src/rendering/twn_gl_15_rendering.c

@@ -161,8 +161,15 @@ static void finally_use_2d_pipeline(void) {
     glOrtho(0, (double)ctx.base_render_width, (double)ctx.base_render_height, 0, 0, 1);
 
     glMatrixMode(GL_MODELVIEW);
-    /* TODO: 2d camera */
     glLoadIdentity();
+    /* rotate against center of the viewport */
+    Vec2 const center_offset = { ctx.game.resolution.x / 2, ctx.game.resolution.y / 2 };
+    glTranslatef(center_offset.x, center_offset.y, 0);
+    glRotatef(camera_2d_rotation, 0, 0, 1);
+    glScalef(camera_2d_zoom, camera_2d_zoom, 1);
+    glTranslatef(-center_offset.x, -center_offset.y, 0);
+    /* apply the rest */
+    glTranslatef(-camera_2d_position.x, -camera_2d_position.y, 0);
 
     texture_mode_last_used = -1;
     pipeline_last_used = PIPELINE_2D;