Babylon.js/src/Shaders/anaglyph.fragment.fx

// Samplers
varying vec2 vUV;
uniform sampler2D textureSampler;
uniform sampler2D leftSampler;

void main(void)
{
    vec4 leftFrag = texture2D(leftSampler, vUV);
    leftFrag = vec4(1.0, leftFrag.g, leftFrag.b, 1.0);

	vec4 rightFrag = texture2D(textureSampler, vUV);
    rightFrag = vec4(rightFrag.r, 1.0, 1.0, 1.0);

    gl_FragColor = vec4(rightFrag.rgb * leftFrag.rgb, 1.0);
}