deferred fog, fix of first frame on double buffered option

src/rendering/twn_gl_15_rendering.c

@@ -147,6 +147,12 @@ typedef struct {
 } DeferredCommandDepthRange;
 
 
+typedef struct {
+    float start, end, density;
+    Color color;
+} DeferredCommandApplyFog;
+
+
 typedef struct {
     enum DeferredCommandType {
         DEFERRED_COMMAND_TYPE_DRAW,
@@ -155,6 +161,8 @@ typedef struct {
         DEFERRED_COMMAND_TYPE_USE_PIPIELINE,
         DEFERRED_COMMAND_TYPE_USE_TEXTURE_MODE,
         DEFERRED_COMMAND_TYPE_DEPTH_RANGE,
+        DEFERRED_COMMAND_TYPE_APPLY_FOG,
+        DEFERRED_COMMAND_TYPE_POP_FOG,
     } type;
 
     union {
@@ -164,6 +172,7 @@ typedef struct {
         DeferredCommandUsePipeline use_pipeline;
         DeferredCommandUseTextureMode use_texture_mode;
         DeferredCommandDepthRange depth_range;
+        DeferredCommandApplyFog apply_fog;
     };
 } DeferredCommand;
 
@@ -208,6 +217,8 @@ static void finally_use_2d_pipeline(void);
 static void finally_use_space_pipeline(void);
 static void finally_use_texture_mode(TextureMode mode);
 static void deferred_render_skybox(char *paths);
+static void deferred_apply_fog(float start, float end, float density, Color color);
+static void deferred_pop_fog(void);
 
 static DeferredCommand *deferred_commands;
 
@@ -346,6 +357,19 @@ static void issue_deferred_draw_commands(void) {
                 break;
             }
 
+            case DEFERRED_COMMAND_TYPE_APPLY_FOG: {
+                deferred_apply_fog(deferred_commands[i].apply_fog.start,
+                                   deferred_commands[i].apply_fog.end,
+                                   deferred_commands[i].apply_fog.density,
+                                   deferred_commands[i].apply_fog.color);
+                break;
+            }
+
+            case DEFERRED_COMMAND_TYPE_POP_FOG: {
+                deferred_pop_fog();
+                break;
+            }
+
             default:
                 SDL_assert(false);
         }
@@ -376,7 +400,7 @@ void start_render_frame(void) {
 
 
 void end_render_frame(void) {
-    if (!ctx.render_double_buffered || ctx.game.frame_number == 0) {
+    if (!ctx.render_double_buffered || ctx.game.frame_number == 1) {
         issue_deferred_draw_commands();
         SDL_GL_SwapWindow(ctx.window);
         arrsetlen(deferred_commands, 0);
@@ -1086,6 +1110,21 @@ static void deferred_render_skybox(char *paths) {
 
 
 void finally_apply_fog(float start, float end, float density, Color color) {
+    DeferredCommand command = {
+        .type = DEFERRED_COMMAND_TYPE_APPLY_FOG,
+        .apply_fog = (DeferredCommandApplyFog){
+            .start = start,
+            .end = end,
+            .density = density,
+            .color = color
+        }
+    };
+
+    arrpush(deferred_commands, command);
+}
+
+
+static void deferred_apply_fog(float start, float end, float density, Color color) {
     if (density < 0.0f || density > 1.0f)
         log_warn("Invalid fog density given, should be in range [0..1]");
 
@@ -1108,6 +1147,15 @@ void finally_apply_fog(float start, float end, float density, Color color) {
 
 
 void finally_pop_fog(void) {
+    DeferredCommand command = {
+        .type = DEFERRED_COMMAND_TYPE_POP_FOG,
+    };
+
+    arrpush(deferred_commands, command);
+}
+
+
+static void deferred_pop_fog(void) {
     glDisable(GL_FOG);
 }