fix: use rgba8 as downgrade shadow texture (#1033)

galacean · Sep 11, 2022 · f6567e6 · f6567e6
1 parent 1bc314f
commit f6567e6
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Showing 3 changed files with 32 additions and 3 deletions.
diff --git a/packages/core/src/shaderlib/extra/shadow-map.fs.glsl b/packages/core/src/shaderlib/extra/shadow-map.fs.glsl
@@ -1,6 +1,24 @@
+#ifdef OASIS_NO_DEPTH_TEXTURE
+/**
+ * Decompose and save depth value.
+*/
+vec4 pack (float depth) {
+  // Use rgba 4 bytes with a total of 32 bits to store the z value, and the accuracy of 1 byte is 1/256.
+  const vec4 bitShift = vec4(1.0, 256.0, 256.0 * 256.0, 256.0 * 256.0 * 256.0);
+  const vec4 bitMask = vec4(1.0/256.0, 1.0/256.0, 1.0/256.0, 0.0);
+
+  vec4 rgbaDepth = fract(depth * bitShift); // Calculate the z value of each point
+
+  // Cut off the value which do not fit in 8 bits
+  rgbaDepth -= rgbaDepth.gbaa * bitMask;
+
+  return rgbaDepth;
+}
+#endif
+
 void main() {
 #ifdef OASIS_NO_DEPTH_TEXTURE
-    gl_FragColor = vec4(gl_FragCoord.z, 0.0, 0.0, 0.0);
+    gl_FragColor = pack(gl_FragCoord.z);
 #else
     gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
 #endif

diff --git a/packages/core/src/shaderlib/shadow/shadow_frag_share.glsl b/packages/core/src/shaderlib/shadow/shadow_frag_share.glsl
@@ -22,7 +22,18 @@
             #define TEXTURE2D_SHADOW_PARAM(shadowMap) mediump sampler2DShadow shadowMap
         #else
             uniform sampler2D u_shadowMap;
-            #define SAMPLE_TEXTURE2D_SHADOW(textureName, coord3) (texture2D(textureName, coord3.xy).r < coord3.z ? 0.0 : 1.0)
+            #ifdef OASIS_NO_DEPTH_TEXTURE
+                const vec4 bitShift = vec4(1.0, 1.0/256.0, 1.0/(256.0*256.0), 1.0/(256.0*256.0*256.0));
+                /**
+                * Unpack depth value.
+                */
+                float unpack(const in vec4 rgbaDepth) {
+                  return dot(rgbaDepth, bitShift);
+                }
+                #define SAMPLE_TEXTURE2D_SHADOW(textureName, coord3) (unpack(texture2D(textureName, coord3.xy)) < coord3.z ? 0.0 : 1.0)
+            #else
+                #define SAMPLE_TEXTURE2D_SHADOW(textureName, coord3) (texture2D(textureName, coord3.xy).r < coord3.z ? 0.0 : 1.0)
+            #endif
             #define TEXTURE2D_SHADOW_PARAM(shadowMap) mediump sampler2D shadowMap
         #endif
 

diff --git a/packages/core/src/shadow/ShadowUtils.ts b/packages/core/src/shadow/ShadowUtils.ts
@@ -169,7 +169,7 @@ export class ShadowUtils {
     if (supportDepthTexture) {
       return TextureFormat.Depth16;
     } else {
-      return TextureFormat.R16G16B16A16;
+      return TextureFormat.R8G8B8A8;
     }
   }