Fix mesh face/element colors

Author: mhochsteger

ngsolve_webgpu/mesh.py

@@ -590,12 +590,18 @@ def __init__(
         self, data: MeshData, clipping=None, colors: list | None = None, label="MeshElements2d"
     ):
         super().__init__(data, label=label, clipping=clipping)
+        
+        def get_color(fd):
+            color = [int(ci*255) for ci in fd.color]
+            if len(color) == 3:
+                color = color + [255]
+            return color
         if colors is None:
             mesh = data.mesh
-            colors = [[int(ci * 255) for ci in fd.color] for fd in mesh.FaceDescriptors()]
-        self.gpu_objects.colormap = Colormap(colormap=colors, minval=-0.5, maxval=len(colors) - 0.5)
+            colors = [get_color(fd) for fd in mesh.FaceDescriptors()]
+        self.gpu_objects.colormap = Colormap(colormap=colors, minval=0, maxval=len(colors)-1)
         self.gpu_objects.colormap.discrete = 0
-        self.gpu_objects.colormap.n_colors = 4 * len(colors)
+        self.gpu_objects.colormap.n_colors = len(colors)
 
     @property
     def colormap(self):
@@ -731,8 +737,8 @@ def __init__(self, data: MeshData, clipping=None, colors: list | None = None, sy
         if colors is None:
             colors = [[255, 0, 0, 255] for _ in range(len(data.ngs_mesh.GetMaterials()))]
         self.gpu_objects.colormap = Colormap(colormap=colors, minval=-0.5, maxval=len(colors) - 0.5)
-        self.gpu_objects.colormap.discrete = 0
-        self.gpu_objects.colormap.n_colors = 4 * len(colors)
+        self.gpu_objects.colormap.discrete = 1
+        self.gpu_objects.colormap.n_colors = len(colors)
         self.symmetry = symmetry
 
     @property

ngsolve_webgpu/shaders/mesh/render.wgsl

@@ -265,7 +265,7 @@ fn fragmentMesh(input: MeshFragmentInput) -> @location(0) vec4<f32> {
 @fragment
 fn fragment2dElement(input: VertexOutput2d) -> @location(0) vec4<f32> {
   checkClipping(input.p);
-  let color = getColor(f32(input.index));
+  let color = getColor(f32(input.index) + 0.5);
   if(color.a < 0.01) {
     discard;
   }
@@ -277,7 +277,7 @@ fn fragment2dElement(input: VertexOutput2d) -> @location(0) vec4<f32> {
     input: VertexOutput2d
 ) -> @location(0) vec4<u32> {
     checkClipping(input.p);
-    let color = getColor(f32(input.index));
+    let color = getColor(f32(input.index) + 0.5);
     if(color.a < 0.01) {
       discard;
     }