Ok thank you Ashley
I think I will use the Vignette effect but I want the vignette colour to be white. I guess I only have to change a paramater from the effect's code, but I've trying for an hour and a half and I really haven't got any clue on how to change it. This is the effect's code:
varying mediump vec2 vTex;
uniform lowp sampler2D samplerFront;
uniform mediump float vignetteStart;
uniform mediump float vignetteEnd;
void main(void)
{
lowp vec4 front = texture2D(samplerFront, vTex);
lowp float a = front.a;
if (a != 0.0)
front.rgb /= a;
lowp float d = distance(vTex, vec2(0.5, 0.5));
front.rgb *= smoothstep(vignetteEnd, vignetteStart, d);
front.rgb *= a;
gl_FragColor = front;
}
[/code:1j59hu63] which is based on [url=https://github.com/BradLarson/GPUImage/blob/master/framework/Source/GPUImageVignetteFilter.m]https://github.com/BradLarson/GPUImage/ ... teFilter.m[/url] and the author gives this hint[quote:1j59hu63]vignetteColor: The color to use for the vignette (GPUVector3), with a default of black