Images and mask in OpenGL ES 2.0

Question

I\'m learning OpenGL ES 2.0 and I\'d like to create an App to better understand how it works. The App has a set of filter that the user can apply on images (I know, nothing

Answer 1

You can apply the mask in one line without using the costly if:

gl_FragColor = step( 0.5, vMask.r ) * vColor_1 + ( 1.0 - step( 0.5, vMask.r ) ) * vColor_2;

Or, better just interpolate between two colors:

gl_FragColor = mix( vColor_1, vColor_2, vMask.r );

In this case the mask can be smoothed (i.e. with Gaussian blur) to produce less aliasing. This will yield very good results compared to a single value thresholding.