Calculate fog opacity in terrain raster fragment shader when zero exa…

…ggeration is used
mapbox · Nov 30, 2022 · 16da14d · 16da14d
1 parent d12e8f9
commit 16da14d
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Showing 3 changed files with 8 additions and 15 deletions.
diff --git a/src/shaders/_prelude_fog.fragment.glsl b/src/shaders/_prelude_fog.fragment.glsl
@@ -77,13 +77,6 @@ vec3 fog_apply(vec3 color, vec3 pos) {
     return mix(color, u_fog_color.rgb, opacity);
 }
 
-// Apply fog computed in the vertex shader
-vec4 fog_apply_from_vert(vec4 color, float fog_opac) {
-    float alpha = EPSILON + color.a;
-    color.rgb = mix(color.rgb / alpha, u_fog_color.rgb, fog_opac) * alpha;
-    return color;
-}
-
 // Assumes z up
 vec3 fog_apply_sky_gradient(vec3 camera_ray, vec3 sky_color) {
     float horizon_blend = fog_horizon_blending(normalize(camera_ray));

diff --git a/src/shaders/terrain_raster.fragment.glsl b/src/shaders/terrain_raster.fragment.glsl
@@ -1,10 +1,6 @@
 uniform sampler2D u_image0;
 varying vec2 v_pos0;
 
-#ifdef FOG
-varying float v_fog_opacity;
-#endif
-
 #ifdef RENDER_SHADOWS
 varying vec4 v_pos_light_view_0;
 varying vec4 v_pos_light_view_1;
@@ -19,7 +15,11 @@ void main() {
 #endif
 
 #ifdef FOG
+#ifdef ZERO_EXAGGERATION
+    color = fog_dither(fog_apply_premultiplied(color, v_fog_pos));
+#else
     color = fog_dither(fog_apply_from_vert(color, v_fog_opacity));
+#endif
 #endif
     gl_FragColor = color;
 #ifdef TERRAIN_WIREFRAME

diff --git a/src/shaders/terrain_raster.vertex.glsl b/src/shaders/terrain_raster.vertex.glsl
@@ -6,10 +6,6 @@ attribute vec2 a_texture_pos;
 
 varying vec2 v_pos0;
 
-#ifdef FOG
-varying float v_fog_opacity;
-#endif
-
 #ifdef RENDER_SHADOWS
 uniform mat4 u_light_matrix_0;
 uniform mat4 u_light_matrix_1;
@@ -32,8 +28,12 @@ void main() {
     gl_Position = u_matrix * vec4(decodedPos, elevation, 1.0);
 
 #ifdef FOG
+#ifdef ZERO_EXAGGERATION
+    v_fog_pos = fog_position(decodedPos);
+#else
     v_fog_opacity = fog(fog_position(vec3(decodedPos, elevation)));
 #endif
+#endif
 
 #ifdef RENDER_SHADOWS
     vec3 pos = vec3(decodedPos, elevation);