Feature: Add an option to control the discretization of colormap

application/F3DOptionsTools.cxx

@@ -136,6 +136,7 @@ static inline const std::array<CLIGroup, 8> CLIOptions = {{
       {"bar", "b", "Show scalar bar", "<bool>", "1" },
       {"colormap-file", "", "Specify a colormap image", "<filePath/filename/fileStem>", ""},
       {"colormap", "", "Specify a custom colormap (ignored if \"colormap-file\" is specified)", "<color_list>", ""},
+      {"colormap-discretization", "", "Specify the discretization of the colormap", "<int>", "256"},
       {"volume", "v", "Show volume if the file is compatible", "<bool>", "1"},
       {"inverse", "i", "Inverse opacity function for volume rendering", "<bool>", "1"} } },
   {"Camera",

application/F3DOptionsTools.h

@@ -113,6 +113,7 @@ static inline const std::map<std::string_view, std::string_view> LibOptionsNames
   { "range", "model.scivis.range" },
   { "bar", "ui.scalar_bar" },
   { "colormap", "model.scivis.colormap" },
+  { "colormap-discretization", "model.scivis.discretization" },
   { "volume", "model.volume.enable" },
   { "inverse", "model.volume.inverse" },
   { "camera-orthographic", "scene.camera.orthographic" },

library/options.json

@@ -246,6 +246,10 @@
         "type": "double_vector",
         "default_value": "0.0, 0.0, 0.0, 0.0, 0.4, 0.9, 0.0, 0.0, 0.8, 0.9, 0.9, 0.0, 1.0, 1.0, 1.0, 1.0"
       },
+      "discretization" : {
+        "type": "int",
+        "default_value": "256"
+      },
       "range": {
         "type": "double_vector"
       }

library/src/window_impl.cxx

@@ -438,6 +438,7 @@ void window_impl::UpdateDynamicOptions()
 
   renderer->SetScalarBarRange(opt.model.scivis.range);
   renderer->SetColormap(opt.model.scivis.colormap);
+  renderer->SetColorDiscretization(opt.model.scivis.discretization);
   renderer->ShowScalarBar(opt.ui.scalar_bar);
 
   renderer->SetUsePointSprites(opt.model.point_sprites.enable);

vtkext/private/module/vtkF3DRenderer.cxx

@@ -283,6 +283,9 @@ void vtkF3DRenderer::Initialize()
 
   this->GridInfo = "";
 
+  this->Discretization = 256;
+  this->DiscretizableColorTransferFunctionConfigured = false;
+
   this->AddActor2D(this->ScalarBarActor);
   this->ScalarBarActor->VisibilityOff();
 
@@ -2125,6 +2128,20 @@ void vtkF3DRenderer::SetColormap(const std::vector<double>& colormap)
   }
 }
 
+void vtkF3DRenderer::SetColorDiscretization(const int discretization) { 
+  if(discretization >= 0 and discretization <= std::numeric_limits<int>::max()) {
+    this->Discretization = discretization;
+
+    bool enableColoring = this->EnableColoring || (!this->UseRaytracing && this->UseVolume);
+    F3DColoringInfoHandler& coloringHandler = this->Importer->GetColoringInfoHandler();
+    auto info = coloringHandler.SetCurrentColoring(enableColoring, this->UseCellColoring, this->ArrayNameForColoring, false);
+    this->ConfigureRangeAndCTFForColoring(info.value());
+  } else {
+    F3DLog::Print(F3DLog::Severity::Error,
+      "The discretization value need to great than zero");
+  }
+}
+
 //----------------------------------------------------------------------------
 void vtkF3DRenderer::SetEnableColoring(bool enable)
 {
@@ -2472,6 +2489,12 @@ void vtkF3DRenderer::ConfigureRangeAndCTFForColoring(
     return;
   }
 
+  // Set Discretization
+  if(!this->DiscretizableColorTransferFunctionConfigured) {
+    this->DiscretizableColorTransferFunction->SetNumberOfValues(this->Discretization);
+    this->DiscretizableColorTransferFunctionConfigured = true;
+  }
+
   // Set range
   bool autoRange = true;
   if (this->UserScalarBarRange.has_value())

vtkext/private/module/vtkF3DRenderer.h

@@ -14,6 +14,7 @@
 #include "vtkF3DMetaImporter.h"
 #include "vtkF3DUIActor.h"
 
+#include <vtkDiscretizableColorTransferFunction.h>
 #include <vtkLight.h>
 #include <vtkOpenGLRenderer.h>
 
@@ -282,6 +283,11 @@ class vtkF3DRenderer : public vtkOpenGLRenderer
    */
   void SetColormap(const std::vector<double>& colormap);
 
+  /**
+   * Set the discretization of the colormap
+   */
+  void SetColorDiscretization(const int discretization);
+
   /**
    * Set the meta importer to recover coloring information from
    */
@@ -557,6 +563,10 @@ class vtkF3DRenderer : public vtkOpenGLRenderer
   vtkF3DMetaImporter* Importer = nullptr;
   vtkMTimeType ImporterTimeStamp = 0;
 
+  vtkNew<vtkDiscretizableColorTransferFunction> DiscretizableColorTransferFunction;
+  bool DiscretizableColorTransferFunctionConfigured = false;
+  int Discretization = 256;
+
   vtkNew<vtkScalarBarActor> ScalarBarActor;
   bool ScalarBarActorConfigured = false;