[Solved] Filter "Godrays" which does not darken the background

[Artfaith]

Dear Community,

 

Thank you very much for the magnificent project!

 

Currently, I am trying to create a filter which is based on a shader ""Godrays" by alaingalvan", but the one which only lightens a certain area where "lights" exist on a transparent stage.

The current version creates dark places ('0x000000') where the "lights" are not shown, but the darkness must not surpass the background ('0x333333' or '0xffffff' as in CSS), so it would look like a transparent filter in the result. This is the incorrect behavior since it creates black background where the "lights" are (it is correct that it affects the background):

 ~ 

 

Is it even possible using this filter/shader? Is it correct that the issue is in the color matrix ("float noise(in vec3 p)")?

Would it be correct to somehow base a pixel color on the source and only increase its "gain" instead?

 

I will highly appreciate any suggestion!

 

Best and kind regards

Edited January 24, 2023 by Artfaith
Marked "Solved"

[Artfaith]

The issue was in the alpha channel! How did I miss...

Got the answer at StackOverflow by Eduardo Páez Rubio and am so grateful!

 

The line 153 must be changed from:

vec4 mist = vec4(noise, noise, noise, 1.0);
noise = mix(noise, 0.0, 0.3);

to:

noise = mix(noise, 0.0, 0.3);
vec4 mist = vec4(noise, noise, noise, noise);

 

Also, the line seems must be swapped with 154.

The working example: https://codepen.io/faither/pen/oNMqBab

Edited January 24, 2023 by Artfaith