Hi,

I just want to understand why, in this shader (rgb split), when I try to get the alpha chanel of tex0, I end up with a kind of red image ? how can I solve this and keep the original colors ?

```
#version 120
uniform sampler2DRect tex0;
uniform float amount = 0.01;
uniform float angle = 0.5;
uniform int invert = 0;
varying vec2 texCoordVarying;
void main() {
vec2 offset = amount * vec2( cos(angle), sin(angle));
vec4 cr = texture2DRect(tex0, texCoordVarying + offset);
vec4 cga = texture2DRect(tex0, texCoordVarying);
vec4 cb = texture2DRect(tex0, texCoordVarying - offset);
vec4 alpha = texture2DRect(tex0, texCoordVarying);
gl_FragColor = vec4(cr.r, cga.g, cb.b, alpha.a);
}
```

Thank’s !