[Bug] Volume Shader compile error with GradientOpacity and clippingPlane

[PaulHax]

Bug description

Getting shader compile error in vtkVolumeFS.glsl

ROR: 0:402: 'IStoVC' : no matching overloaded function found
ERROR: 0:402: '=' : dimension mismatch
ERROR: 0:402: '=' : cannot convert from 'const mediump float' to 'highp 3-component vector of float'

Steps to reproduce

Add these lines to VolumeMapperBlendModes example:

import vtkPlane from '@kitware/vtk.js/Common/DataModel/Plane';
actor.getProperty().setUseGradientOpacity(0, true);
const clipPlane1 = vtkPlane.newInstance();
mapper.addClippingPlane(clipPlane1);

Detailed Behavior

Trouble is somewhere around here:

vtk-js/Sources/Rendering/OpenGL/glsl/vtkVolumeFS.glsl

Lines 367 to 377 in 2dd7e3f

	// compute the normal and gradient magnitude for a position, uses forward difference
	#if (vtkLightComplexity > 0) || (defined vtkGradientOpacityOn)
	#ifdef vtkClippingPlanesOn
	void adjustClippedVoxelValues(vec3 pos, vec3 texPos[3], inout vec3 g1)
	{
	vec3 g1VC[3];
	for (int i = 0; i < 3; ++i)
	{
	g1VC[i] = IStoVC(texPos[i]);
	}
	vec3 posVC = IStoVC(pos);

Expected Behavior

No shader compile error.

Environment

• vtk.js version: v28.0.0
• Browsers: Chrome
• OS: Linux

[thewtex]

@sankhesh related to your recent changes? fc928f0 fee91eb

[github-actions]

🎉 This issue has been resolved in version 28.0.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• npm package (@latest dist-tag)
• GitHub release

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