1 files changed, 17 insertions, 41 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/effect_minmaxz_frag.glsl b/source/blender/draw/engines/eevee/shaders/effect_minmaxz_frag.glsl
index b99037b1e80..ccb65d2e5a6 100644
--- a/source/blender/draw/engines/eevee/shaders/effect_minmaxz_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/effect_minmaxz_frag.glsl
@@ -2,6 +2,9 @@
  * Shader that down-sample depth buffer,
  * saving min and max value of each texel in the above mipmaps.
  * Adapted from http://rastergrid.com/blog/2010/10/hierarchical-z-map-based-occlusion-culling/
+ *
+ * Major simplification has been made since we pad the buffer to always be bigger than input to
+ * avoid mipmapping misalignement.
  */
 
 #ifdef LAYERED
@@ -12,10 +15,10 @@ uniform sampler2D depthBuffer;
 #endif
 
 #ifdef LAYERED
-#  define sampleLowerMip(t) texelFetch(depthBuffer, ivec3(t, depthLayer), 0).r
+#  define sampleLowerMip(t) texture(depthBuffer, vec3(t, depthLayer)).r
 #  define gatherLowerMip(t) textureGather(depthBuffer, vec3(t, depthLayer))
 #else
-#  define sampleLowerMip(t) texelFetch(depthBuffer, t, 0).r
+#  define sampleLowerMip(t) texture(depthBuffer, t).r
 #  define gatherLowerMip(t) textureGather(depthBuffer, t)
 #endif
 
@@ -37,54 +40,27 @@ out vec4 fragColor;
 
 void main()
 {
-  ivec2 texelPos = ivec2(gl_FragCoord.xy);
-  ivec2 mipsize = textureSize(depthBuffer, 0).xy;
-
-#ifndef COPY_DEPTH
-  texelPos *= 2;
-#endif
+  vec2 texel = gl_FragCoord.xy;
+  vec2 texel_size = 1.0 / vec2(textureSize(depthBuffer, 0).xy);
 
 #ifdef COPY_DEPTH
-  float val = sampleLowerMip(texelPos);
+  vec2 uv = texel * texel_size;
+
+  float val = sampleLowerMip(uv);
 #else
+  vec2 uv = texel * 2.0 * texel_size;
+
   vec4 samp;
 #  ifdef GPU_ARB_texture_gather
-  /* + 1.0 to gather at the center of target 4 texels. */
-  samp = gatherLowerMip((vec2(texelPos) + 1.0) / vec2(mipsize));
+  samp = gatherLowerMip(uv);
 #  else
-  samp.x = sampleLowerMip(texelPos);
-  samp.y = sampleLowerMip(texelPos + ivec2(1, 0));
-  samp.z = sampleLowerMip(texelPos + ivec2(1, 1));
-  samp.w = sampleLowerMip(texelPos + ivec2(0, 1));
+  samp.x = sampleLowerMip(uv + vec2(-0.5, -0.5) * texel_size);
+  samp.y = sampleLowerMip(uv + vec2(-0.5, 0.5) * texel_size);
+  samp.z = sampleLowerMip(uv + vec2(0.5, -0.5) * texel_size);
+  samp.w = sampleLowerMip(uv + vec2(0.5, 0.5) * texel_size);
 #  endif
 
   float val = minmax4(samp.x, samp.y, samp.z, samp.w);
-
-  /* if we are reducing an odd-width texture then fetch the edge texels */
-  if (((mipsize.x & 1) != 0) && (texelPos.x == mipsize.x - 3)) {
-    /* if both edges are odd, fetch the top-left corner texel */
-    if (((mipsize.y & 1) != 0) && (texelPos.y == mipsize.y - 3)) {
-      samp.x = sampleLowerMip(texelPos + ivec2(2, 2));
-      val = minmax2(val, samp.x);
-    }
-#  ifdef GPU_ARB_texture_gather
-    samp = gatherLowerMip((vec2(texelPos) + vec2(2.0, 1.0)) / vec2(mipsize));
-#  else
-    samp.y = sampleLowerMip(texelPos + ivec2(2, 0));
-    samp.z = sampleLowerMip(texelPos + ivec2(2, 1));
-#  endif
-    val = minmax3(val, samp.y, samp.z);
-  }
-  /* if we are reducing an odd-height texture then fetch the edge texels */
-  if (((mipsize.y & 1) != 0) && (texelPos.y == mipsize.y - 3)) {
-#  ifdef GPU_ARB_texture_gather
-    samp = gatherLowerMip((vec2(texelPos) + vec2(1.0, 2.0)) / vec2(mipsize));
-#  else
-    samp.x = sampleLowerMip(texelPos + ivec2(0, 2));
-    samp.y = sampleLowerMip(texelPos + ivec2(1, 2));
-#  endif
-    val = minmax3(val, samp.x, samp.y);
-  }
 #endif
 
 #if defined(GPU_INTEL) || defined(GPU_ATI)