big rendering overhaul (cleaning and api abstraction)

include/twn_context.h

@@ -23,6 +23,10 @@ typedef struct Context {
     /* TODO: actually set it */
     float frame_duration;
 
+    /* it is disabled by having fog_density approximately equal to zero */
+    float fog_start, fog_end, fog_density;
+    Color fog_color;
+
     /* resolution is set from config and dictates both logical and drawing space, as they're related */
     /* even if scaling is done, game logic should never change over that */
     Vec2 resolution;

include/twn_draw.h

@@ -88,12 +88,6 @@ TWN_API DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 p
 /* expects '*' masks that will be expanded to 6 names: 'up', 'down', 'east', 'west', 'north' and 'south' */
 TWN_API void draw_skybox(const char *textures);
 
-/* only one for setting is supported for a frame, any call overwrites previous */
-TWN_API void draw_fog(float start,      /* optional, default: 0.0 */
-                      float end,        /* optional, default: 1.0 */
-                      float density,    /* optional, default: 0.0 */
-                      Color color);     /* optional, default: all 255 */
-
 
 #ifndef TWN_NOT_C
 

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_COUNT,
     TEXTURE_MODE_UNKNOWN = -1,  /* a sentinel */
 } TextureMode;