deferred skybox, fixes to use of ARB_depth_clamp extension usage, have TextureKey explicitly in QuadBatch

include/twn_texture_modes.h

@@ -9,6 +9,7 @@ typedef enum TextureMode {
     TEXTURE_MODE_OPAQUE,        /* all pixels are solid */
     TEXTURE_MODE_SEETHROUGH,  	/* some pixels are alpha zero */
     TEXTURE_MODE_GHOSTLY,       /* arbitrary alpha values */
+    TEXTURE_MODE_UNKNOWN = -1,  /* a sentinel */
 } TextureMode;
 
 #endif

src/rendering/twn_draw_c.h

@@ -137,6 +137,7 @@ void create_circle_geometry(Vec2 position,
 
 struct QuadBatch {
     size_t size;             /* how many primitives are in current batch */
+    TextureKey texture_key;
     TextureMode mode;        /* how color should be applied */
     bool constant_colored;   /* whether colored batch is uniformly colored */
     bool repeat;             /* whether repeat is needed */

src/rendering/twn_gl_15_rendering.c

@@ -31,6 +31,7 @@ typedef struct ElementIndexedQuad {
     Color c3;
 } ElementIndexedQuad;
 
+
 typedef struct ElementIndexedQuadWithoutColor {
     /* upper-left */
     Vec2 v0;
@@ -111,6 +112,11 @@ typedef struct {
 } DeferredCommandDraw;
 
 
+typedef struct {
+    char *paths;
+} DeferredCommandDrawSkybox;
+
+
 typedef struct {
     Color color;
     bool clear_color;
@@ -144,6 +150,7 @@ typedef struct {
 typedef struct {
     enum DeferredCommandType {
         DEFERRED_COMMAND_TYPE_DRAW,
+        DEFERRED_COMMAND_TYPE_DRAW_SKYBOX,
         DEFERRED_COMMAND_TYPE_CLEAR,
         DEFERRED_COMMAND_TYPE_USE_PIPIELINE,
         DEFERRED_COMMAND_TYPE_USE_TEXTURE_MODE,
@@ -152,6 +159,7 @@ typedef struct {
 
     union {
         DeferredCommandDraw draw;
+        DeferredCommandDrawSkybox draw_skybox;
         DeferredCommandClear clear;
         DeferredCommandUsePipeline use_pipeline;
         DeferredCommandUseTextureMode use_texture_mode;
@@ -160,7 +168,7 @@ typedef struct {
 } DeferredCommand;
 
 
-static TextureMode texture_mode_last_used = -1;
+static TextureMode texture_mode_last_used = TEXTURE_MODE_UNKNOWN;
 static Pipeline pipeline_last_used = PIPELINE_NO;
 
 
@@ -199,6 +207,7 @@ GLuint get_scratch_vertex_array(void) {
 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 DeferredCommand *deferred_commands;
 
@@ -311,6 +320,11 @@ static void issue_deferred_draw_commands(void) {
                 break;
             }
 
+            case DEFERRED_COMMAND_TYPE_DRAW_SKYBOX: {
+                deferred_render_skybox(deferred_commands[i].draw_skybox.paths);
+                break;
+            }
+
             case DEFERRED_COMMAND_TYPE_USE_PIPIELINE: {
                 switch (deferred_commands[i].use_pipeline.pipeline) {
                     case PIPELINE_2D:
@@ -457,7 +471,7 @@ static void finally_use_2d_pipeline(void) {
 
             /* removes near/far plane comparison and discard */
             if (GLAD_GL_ARB_depth_clamp)
-                glDisable(GL_DEPTH_CLAMP);
+                glEnable(GL_DEPTH_CLAMP);
 
             glEnable(GL_TEXTURE_2D);
             glActiveTexture(GL_TEXTURE0);
@@ -629,9 +643,8 @@ void finally_render_quads(const Primitive2D primitives[],
     }
 
     if (batch.textured) {
-        /* TODO: bad, don't */
         command.textured = true;
-        command.texture_key = primitives->sprite.texture_key;
+        command.texture_key = batch.texture_key;
         command.texture_repeat = batch.repeat;
     }
 
@@ -913,6 +926,18 @@ void render_circle(const CirclePrimitive *circle) {
 
 
 void finally_render_skybox(char *paths) {
+    DeferredCommand command = {
+        .type = DEFERRED_COMMAND_TYPE_DRAW_SKYBOX,
+        .draw_skybox = (DeferredCommandDrawSkybox){
+            .paths = paths
+        }
+    };
+
+    arrpush(deferred_commands, command);
+}
+
+
+static void deferred_render_skybox(char *paths) {
     static GLuint cubemap = 0;
     static char *paths_cache = NULL;
 
@@ -981,6 +1006,10 @@ void finally_render_skybox(char *paths) {
             glDisable(GL_ALPHA_TEST);
             glDepthMask(GL_FALSE);
 
+            /* removes near/far plane comparison and discard */
+            if (GLAD_GL_ARB_depth_clamp)
+                glEnable(GL_DEPTH_CLAMP);
+
             glBegin(GL_QUADS); {
                 /* up */
                 glTexCoord3f(50.f, 50.f, 50.f);
@@ -1043,6 +1072,9 @@ void finally_render_skybox(char *paths) {
                 glVertex3f(-50.f, 50.f, -50.f);
             } glEnd();
 
+            if (GLAD_GL_ARB_depth_clamp)
+                glDisable(GL_DEPTH_CLAMP);
+
             glDepthMask(GL_TRUE);
             glDisable(GL_TEXTURE_CUBE_MAP);
 

src/rendering/twn_sprites.c

@@ -69,6 +69,7 @@ struct QuadBatch collect_sprite_batch(const Primitive2D primitives[], size_t len
 
     struct QuadBatch batch = {
         .mode = textures_get_mode(&ctx.texture_cache, primitives[0].sprite.texture_key),
+        .texture_key = primitives[0].sprite.texture_key,
         .constant_colored = true,
         .repeat = primitives[0].sprite.repeat,
         .textured = true,