diff --git a/src/mol-gl/shader/direct-volume.frag.ts b/src/mol-gl/shader/direct-volume.frag.ts
index bcb2d4728825ecad05dca94e669850d40ccd12c7..a1786de3fcf07c324261cafd11cab859f25af1b8 100644
--- a/src/mol-gl/shader/direct-volume.frag.ts
+++ b/src/mol-gl/shader/direct-volume.frag.ts
@@ -62,6 +62,12 @@ uniform int uGroupCount;
     uniform sampler2D tMarker;
 #endif
 
+#if defined(dRenderVariant_colorDpoit)
+    #define MAX_DPOIT_DEPTH 99999.0
+    uniform sampler2D tDpoitDepth;
+    uniform sampler2D tDpoitFrontColor;
+#endif
+
 uniform float uMetalness;
 uniform float uRoughness;