Ensure that gl_FragDepth is set as-intended with tubes/spheres.

The depth was being set in //VTK::Normal::Impl, while the default //VTK::Depth::Impl was still being used. The default depth was being used for determining fragment depth during depth peeling, which led to artifacts on translucent objects. Refactoring the shaders to set the tube/sphere depth using the appropriate hook fixes issue #17482.
Kitware · Jan 15, 2019 · 8099519 · 8099519
1 parent 6b0342d
commit 8099519
Showing 1 changed file with 28 additions and 19 deletions.
diff --git a/Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx b/Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx
@@ -1296,19 +1296,24 @@ void vtkOpenGLPolyDataMapper::ReplaceShaderNormal(
       "uniform float ZCalcR;\n"
       );
     vtkShaderProgram::Substitute(FSSource,
-      "//VTK::Normal::Impl",
+      "//VTK::Depth::Impl",
+      "float xpos = 2.0*gl_PointCoord.x - 1.0;\n"
+      "  float ypos = 1.0 - 2.0*gl_PointCoord.y;\n"
+      "  float len2 = xpos*xpos+ ypos*ypos;\n"
+      "  if (len2 > 1.0) { discard; }\n"
+      "  vec3 normalVCVSOutput = normalize(\n"
+      "    vec3(2.0*gl_PointCoord.x - 1.0, 1.0 - 2.0*gl_PointCoord.y, sqrt(1.0 - len2)));\n"
+      "  gl_FragDepth = gl_FragCoord.z + normalVCVSOutput.z*ZCalcS*ZCalcR;\n"
+      "  if (cameraParallel == 0)\n"
+      "  {\n"
+      "    float ZCalcQ = (normalVCVSOutput.z*ZCalcR - 1.0);\n"
+      "    gl_FragDepth = (ZCalcS - gl_FragCoord.z) / ZCalcQ + ZCalcS;\n"
+      "  }\n"
+      );
 
-      " float xpos = 2.0*gl_PointCoord.x - 1.0;\n"
-      " float ypos = 1.0 - 2.0*gl_PointCoord.y;\n"
-      " float len2 = xpos*xpos+ ypos*ypos;\n"
-      " if (len2 > 1.0) { discard; }\n"
-      " vec3 normalVCVSOutput = normalize(\n"
-      "   vec3(2.0*gl_PointCoord.x - 1.0, 1.0 - 2.0*gl_PointCoord.y, sqrt(1.0 - len2)));\n"
-
-      " gl_FragDepth = gl_FragCoord.z + normalVCVSOutput.z*ZCalcS*ZCalcR;\n"
-      " if (cameraParallel == 0) {\n"
-      "  float ZCalcQ = (normalVCVSOutput.z*ZCalcR - 1.0);\n"
-      "  gl_FragDepth = (ZCalcS - gl_FragCoord.z) / ZCalcQ + ZCalcS; }\n"
+    vtkShaderProgram::Substitute(FSSource,
+      "//VTK::Normal::Impl",
+      "//Normal computed in Depth::Impl"
       );
 
      shaders[vtkShader::Fragment]->SetSource(FSSource);
@@ -1341,15 +1346,19 @@ void vtkOpenGLPolyDataMapper::ReplaceShaderNormal(
       "uniform float ZCalcR;\n"
       );
     vtkShaderProgram::Substitute(FSSource,
-      "//VTK::Normal::Impl",
-
+      "//VTK::Depth::Impl",
       "float len2 = tubeBasis1.x*tubeBasis1.x + tubeBasis1.y*tubeBasis1.y;\n"
-      "float lenZ = clamp(sqrt(1.0 - len2),0.0,1.0);\n"
+      "  float lenZ = clamp(sqrt(1.0 - len2),0.0,1.0);\n"
+      "  gl_FragDepth = gl_FragCoord.z + lenZ*ZCalcS*ZCalcR/clamp(tubeBasis2.z,0.5,1.0);\n"
+      "  if (cameraParallel == 0)\n"
+      "  {\n"
+      "    float ZCalcQ = (lenZ*ZCalcR/clamp(tubeBasis2.z,0.5,1.0) - 1.0);\n"
+      "    gl_FragDepth = (ZCalcS - gl_FragCoord.z) / ZCalcQ + ZCalcS;\n"
+      "  }\n"
+      );
+    vtkShaderProgram::Substitute(FSSource,
+      "//VTK::Normal::Impl",
       "vec3 normalVCVSOutput = normalize(tubeBasis1 + tubeBasis2*lenZ);\n"
-      " gl_FragDepth = gl_FragCoord.z + lenZ*ZCalcS*ZCalcR/clamp(tubeBasis2.z,0.5,1.0);\n"
-      " if (cameraParallel == 0) {\n"
-      "  float ZCalcQ = (lenZ*ZCalcR/clamp(tubeBasis2.z,0.5,1.0) - 1.0);\n"
-      "  gl_FragDepth = (ZCalcS - gl_FragCoord.z) / ZCalcQ + ZCalcS; }\n"
       );
 
     vtkShaderProgram::Substitute(GSSource,