fix grid-absolute for off-center models (#1049)

application/testing/CMakeLists.txt

@@ -123,7 +123,7 @@ f3d_test(NAME TestGridX DATA suzanne.ply ARGS -g --up=+X DEFAULT_LIGHTS)
 f3d_test(NAME TestGridY DATA suzanne.ply ARGS -g --up=+Y DEFAULT_LIGHTS)
 f3d_test(NAME TestGridZ DATA suzanne.ply ARGS -g --up=+Z DEFAULT_LIGHTS)
 f3d_test(NAME TestGridOptions DATA suzanne.ply ARGS -g --camera-elevation-angle=45 --grid-unit=2 --grid-subdivisions=3 -t DEFAULT_LIGHTS)
-f3d_test(NAME TestGridAbsolute DATA suzanne.ply ARGS -g --camera-elevation-angle=45 --grid-absolute -t DEFAULT_LIGHTS)
+f3d_test(NAME TestGridAbsolute DATA f3d.vtp ARGS -g --up=-Y --camera-direction=-.5,+1,+1 --grid-absolute -t DEFAULT_LIGHTS)
 f3d_test(NAME TestAxis DATA suzanne.ply ARGS -x DEFAULT_LIGHTS)
 f3d_test(NAME TestPointCloud DATA pointsCloud.vtp ARGS -o --point-size=20 DEFAULT_LIGHTS) # Using default lights because of ResetCamera
 f3d_test(NAME TestPointCloudBar DATA pointsCloud.vtp ARGS -sob --point-size=20 DEFAULT_LIGHTS) # Using default lights because of ResetCamera

library/VTKExtensions/Rendering/vtkF3DOpenGLGridMapper.cxx

@@ -40,16 +40,20 @@ void vtkF3DOpenGLGridMapper::ReplaceShaderValues(
   std::string VSSource = shaders[vtkShader::Vertex]->GetSource();
   std::string FSSource = shaders[vtkShader::Fragment]->GetSource();
 
-  const std::string axes = this->UpIndex == 0 ? "zyx" : this->UpIndex == 1 ? "xzy" : "xyz";
+  const std::string axes3d = this->UpIndex == 0 ? "zyx" : this->UpIndex == 1 ? "xzy" : "xyz";
+  const std::string axes2d = this->UpIndex == 0 ? "zy" : this->UpIndex == 1 ? "xz" : "xy";
 
   // clang-format off
   vtkShaderProgram::Substitute(VSSource, "//VTK::PositionVC::Dec",
+    "uniform vec3 originOffset;\n"
     "uniform float fadeDist;\n"
     "out vec2 gridCoord;\n"
+    "out vec2 gridOffset;\n"
   );
   vtkShaderProgram::Substitute(VSSource, "//VTK::PositionVC::Impl",
     "gridCoord = vertexMC.xy * fadeDist;\n"
-    "gl_Position = MCDCMatrix * vec4(vertexMC." + axes + " * fadeDist, 1.0);\n"
+    "gridOffset = originOffset." + axes2d + ";\n"
+    "gl_Position = MCDCMatrix * vec4(vertexMC." + axes3d + " * fadeDist, 1.0);\n"
   );
 
   vtkShaderProgram::Substitute(FSSource, "//VTK::CustomUniforms::Dec",
@@ -63,6 +67,7 @@ void vtkF3DOpenGLGridMapper::ReplaceShaderValues(
     "uniform vec4 axis1Color;\n"
     "uniform vec4 axis2Color;\n"
     "in vec2 gridCoord;\n"
+    "in vec2 gridOffset;\n"
 
     "float antialias(float dist, float linewidth){\n"
     "  float aa = lineAntialias;\n"
@@ -75,7 +80,8 @@ void vtkF3DOpenGLGridMapper::ReplaceShaderValues(
     "}\n"
   );
   vtkShaderProgram::Substitute(FSSource, "//VTK::UniformFlow::Impl",
-    "  vec2 majorCoord = gridCoord / unitSquare;\n"
+    "  vec2 fromCenter = gridCoord / unitSquare;\n"
+    "  vec2 majorCoord = (gridCoord - gridOffset) / unitSquare;\n"
     "  vec2 minorCoord = majorCoord * float(subdivisions);\n"
     "  vec2 majorGrid = abs(fract(majorCoord - 0.5) - 0.5) / fwidth(majorCoord);\n"
     "  vec2 minorGrid = abs(fract(minorCoord - 0.5) - 0.5) / fwidth(minorCoord);\n"
@@ -92,7 +98,7 @@ void vtkF3DOpenGLGridMapper::ReplaceShaderValues(
     "  color = mix(color, axis2Color, axis2Weight);\n"
     "  color = mix(color, axis1Color, axis1Weight);\n"
 
-    "  float sqDist = unitSquare * unitSquare * dot(majorCoord, majorCoord);\n"
+    "  float sqDist = unitSquare * unitSquare * dot(fromCenter, fromCenter);\n"
     "  float radialFadeFactor = 1.0 - sqDist / (fadeDist * fadeDist);\n"
     "  color.w *= radialFadeFactor;\n"
 
@@ -143,6 +149,7 @@ void vtkF3DOpenGLGridMapper::SetMapperShaderParameters(
     }
   }
 
+  cellBO.Program->SetUniform3f("originOffset", this->OriginOffset);
   cellBO.Program->SetUniformf("fadeDist", this->FadeDistance);
   cellBO.Program->SetUniformf("unitSquare", this->UnitSquare);
   cellBO.Program->SetUniformi("subdivisions", this->Subdivisions);

library/VTKExtensions/Rendering/vtkF3DOpenGLGridMapper.h

@@ -17,6 +17,11 @@ class vtkF3DOpenGLGridMapper : public vtkOpenGLPolyDataMapper
   vtkTypeMacro(vtkF3DOpenGLGridMapper, vtkOpenGLPolyDataMapper);
   void PrintSelf(ostream& os, vtkIndent indent) override;
 
+  /**
+   * Set the origin of the axes relative to the actor position
+   */
+  vtkSetVector3Macro(OriginOffset, double);
+
   /**
    * Set the distance where the grid disappear.
    */
@@ -59,6 +64,7 @@ class vtkF3DOpenGLGridMapper : public vtkOpenGLPolyDataMapper
 
   bool GetNeedToRebuildShaders(vtkOpenGLHelper& cellBO, vtkRenderer* ren, vtkActor* act) override;
 
+  double OriginOffset[3] = { 0.0, 0.0, 0.0 };
   double FadeDistance = 10.0;
   double UnitSquare = 1.0;
   int Subdivisions = 10;

library/VTKExtensions/Rendering/vtkF3DRenderer.cxx

@@ -487,7 +487,14 @@ void vtkF3DRenderer::ConfigureGridUsingCurrentActors()
       }
 
       double gridPos[3] = { 0, 0, 0 };
-      if (!this->GridAbsolute)
+      if (this->GridAbsolute)
+      {
+        for (int i = 0; i < 3; i++)
+        {
+          gridPos[i] = this->UpVector[i] ? 0 : 0.5 * (bounds[2 * i] + bounds[2 * i + 1]);
+        }
+      }
+      else
       {
         for (int i = 0; i < 3; i++)
         {
@@ -507,6 +514,8 @@ void vtkF3DRenderer::ConfigureGridUsingCurrentActors()
       gridMapper->SetUnitSquare(tmpUnitSquare);
       gridMapper->SetSubdivisions(this->GridSubdivisions);
       gridMapper->SetUpIndex(this->UpIndex);
+      if (this->GridAbsolute)
+        gridMapper->SetOriginOffset(-gridPos[0], -gridPos[1], -gridPos[2]);
 
       this->GridActor->GetProperty()->SetColor(0.0, 0.0, 0.0);
       this->GridActor->ForceTranslucentOn();