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I have a big trouble about FrameBuffer before I read this article,thinks for you!
How to pass 2 textures to the shader with FBO in order to e.g. blend images? I need that for multiple images (in each iteration compare current texture with next texture(s) in stack).
You declare 2 sampler2D uniforms and set each one 2 a different texture.
uniform sampler2D u_image1;
uniform sampler2D u_image2;
vec4 color1 = texture2D(u_image1, v_texCoord);
vec4 color2 = texture2D(u_image2, v_texCoord);
gl_FragColor = color1 * color2;