surface shader - fix uniform control flow for texture accesses

melowntech · Jul 9, 2018 · e2058f0 · e2058f0
1 parent 59d98f6
commit e2058f0
Showing 1 changed file with 11 additions and 8 deletions.
diff --git a/browser/src/vts-librenderer/data/shaders/surface.frag.glsl b/browser/src/vts-librenderer/data/shaders/surface.frag.glsl
@@ -16,22 +16,25 @@ void main()
 {
     // texture color
     vec4 color = texture(texColor, varUvTex);
-    if (uniFlags.y > 0)
-        color = color.rrra; // monochromatic texture
+
+    // mask
+    if (uniFlags.x > 0)
+    {
+        if (texture(texMask, varUvTex).r < 0.5)
+            discard;
+    }
 
     // uv clipping
+    // uv clipping must go after all texture accesses to allow for computation of derivatives in uniform control flow
     if (varUvClip.x < uniUvClip.x
             || varUvClip.y < uniUvClip.y
             || varUvClip.x > uniUvClip.z
             || varUvClip.y > uniUvClip.w)
         discard;
 
-    // mask
-    if (uniFlags.x > 0)
-    {
-        if (texture(texMask, varUvTex).r < 0.5)
-            discard;
-    }
+    // monochromatic texture
+    if (uniFlags.y > 0)
+        color = color.rrra;
 
     // base color
     if (uniFlags.z > 0)