Alpha blending
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Hello,
I am trying to pass color values as attributes to fragment shader in order to implement a custom geometry gradient with alpha blending using QSGSimpleMaterial and QSGSimpleMaterialShader. The problem is that where there is low opacity the resulting color goes to white. I suspect this is because the alpha blending is not happening correctly but the color at a fragment is getting added to the destination color and gets saturated to white. How can I prevent this? Is there a way to access the destination color or the background color (not gl_Fragcolor) in the fragment shader somehow to be able to change the alpha blending? My code looks like this...
vertice shader:
attribute highp vec4 pos;
attribute highp vec4 color;uniform highp mat4 qt_Matrix;
varying highp vec4 vC;void main(void)
{
gl_Position = qt_Matrix * pos;
vC = color;
}fragment shader:
uniform lowp float qt_Opacity;
varying highp vec4 vC;
void main(void)
{
gl_FragColor = vC * qt_Opacity;
}Any help appreciated, thanks!