fix(WebGL): fix textures with specular lighting

The texture color was being applied after the lighting
calulations causing it to color the specular highlights.

THis change makes it so that the texture applies to the
ambient, diffuse and opacity components which THEN get
put through the lighting equation.

Author: martinken

Sources/Rendering/OpenGL/PolyDataMapper/index.js

@@ -782,9 +782,9 @@ function vtkOpenGLPolyDataMapper(publicAPI, model) {
                 FSSource,
                 '//VTK::TCoord::Impl',
                 [
-                  'vec4 tcolor = texture2D(texture1, tcoordVCVSOutput);',
-                  'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*',
-                  '  vec4(tcolor.r,tcolor.r,tcolor.r,1.0);',
+                  '  vec4 tcolor = texture2D(texture1, tcoordVCVSOutput);',
+                  '  ambientColor = ambientColor*tcolor.r;',
+                  '  diffuseColor = diffuseColor*tcolor.r;',
                 ]
               ).result;
               break;
@@ -793,17 +793,23 @@ function vtkOpenGLPolyDataMapper(publicAPI, model) {
                 FSSource,
                 '//VTK::TCoord::Impl',
                 [
-                  'vec4 tcolor = texture2D(texture1, tcoordVCVSOutput);',
-                  'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*',
-                  '  vec4(tcolor.r,tcolor.r,tcolor.r,tcolor.g);',
+                  '  vec4 tcolor = texture2D(texture1, tcoordVCVSOutput);',
+                  '  ambientColor = ambientColor*tcolor.r;',
+                  '  diffuseColor = diffuseColor*tcolor.r;',
+                  '  opacity = opacity * tcolor.g;',
                 ]
               ).result;
               break;
             default:
               FSSource = vtkShaderProgram.substitute(
                 FSSource,
                 '//VTK::TCoord::Impl',
-                'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*texture2D(texture1, tcoordVCVSOutput.st);'
+                [
+                  '  vec4 tcolor = texture2D(texture1, tcoordVCVSOutput);',
+                  '  ambientColor = ambientColor*tcolor.rgb;',
+                  '  diffuseColor = diffuseColor*tcolor.rgb;',
+                  '  opacity = opacity * tcolor.a;',
+                ]
               ).result;
           }
         }
@@ -832,9 +838,9 @@ function vtkOpenGLPolyDataMapper(publicAPI, model) {
               FSSource,
               '//VTK::TCoord::Impl',
               [
-                'vec4 tcolor = textureCube(texture1, tcoordVCVSOutput);',
-                'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*',
-                '  vec4(tcolor.r,tcolor.r,tcolor.r,1.0);',
+                '  vec4 tcolor = textureCube(texture1, tcoordVCVSOutput);',
+                '  ambientColor = ambientColor*tcolor.r;',
+                '  diffuseColor = diffuseColor*tcolor.r;',
               ]
             ).result;
             break;
@@ -843,17 +849,23 @@ function vtkOpenGLPolyDataMapper(publicAPI, model) {
               FSSource,
               '//VTK::TCoord::Impl',
               [
-                'vec4 tcolor = textureCube(texture1, tcoordVCVSOutput);',
-                'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*',
-                '  vec4(tcolor.r,tcolor.r,tcolor.r,tcolor.g);',
+                '  vec4 tcolor = textureCube(texture1, tcoordVCVSOutput);',
+                '  ambientColor = ambientColor*tcolor.r;',
+                '  diffuseColor = diffuseColor*tcolor.r;',
+                '  opacity = opacity * tcolor.g;',
               ]
             ).result;
             break;
           default:
             FSSource = vtkShaderProgram.substitute(
               FSSource,
               '//VTK::TCoord::Impl',
-              'gl_FragData[0] = clamp(gl_FragData[0],0.0,1.0)*textureCube(texture1, tcoordVCVSOutput);'
+              [
+                '  vec4 tcolor = textureCube(texture1, tcoordVCVSOutput);',
+                '  ambientColor = ambientColor*tcolor.rgb;',
+                '  diffuseColor = diffuseColor*tcolor.rgb;',
+                '  opacity = opacity * tcolor.a;',
+              ]
             ).result;
         }
       }

Sources/Rendering/OpenGL/glsl/vtkPolyDataFS.glsl

@@ -77,10 +77,10 @@ void main()
   // Generate the normal if we are not passed in one
   //VTK::Normal::Impl
 
-  //VTK::Light::Impl
-
   //VTK::TCoord::Impl
 
+  //VTK::Light::Impl
+
   if (gl_FragData[0].a <= 0.0)
     {
     discard;