MeshMatcapMaterial matcap texture offset and matrix transformation

Gase12 · November 8, 2019, 11:32am

is this feature supported?
material.matcap is a texture, but setting the matrix, rotation or offset doesn’t seem to effect the scene
testing with this scene:
https://threejs.org/examples/webgl_materials_matcap.html

thnaks.

Mugen87 · November 8, 2019, 12:06pm

The sampling of a mat cap does not rely on texture coordinates. Hence, changing the uv transformation has no effect.

FYI: The uv value for mat caps is computed like so:

github.com

mrdoob/three.js/blob/8e60034bfa521e0d184adb6b81c9132dac042f61/src/renderers/shaders/ShaderLib/meshmatcap_frag.glsl.js#L40-L43


	vec3 viewDir = normalize( vViewPosition );
	vec3 x = normalize( vec3( viewDir.z, 0.0, - viewDir.x ) );
	vec3 y = cross( viewDir, x );
	vec2 uv = vec2( dot( x, normal ), dot( y, normal ) ) * 0.495 + 0.5; // 0.495 to remove artifacts caused by undersized matcap disks

Gase12 · November 8, 2019, 2:39pm

thx for the info @Mugen87. I was afraid.
so custom shader is the way.

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MeshMatcapMaterial matcap texture offset and matrix transformation

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