This demo certainly uses texture sampling from the vertex shader. It's a feature that enables a lot of fun effects, but is not required by the spec. Check thi

This demo certainly uses texture sampling from the vertex shader. It's a feature that enables a lot of fun effects, but is not required by the spec. Check this page to see if your MAX_VERTEX_TEXTURE_IMAGE_UNITS is > 0 http://renderingpipeline.com/webgl-extension-viewer/ http://renderingpipeline.com/webgl-extension-viewer/