Return shader " " after calling optimizer multiple time

[cedricpinson]

I dont know exactly how, but after optimizing multiple shaders, the optimizer return " " without error. you can reproduce the issue with this url http://osgjs.org/examples/pbr/?GLSLOptimizer=1 There are extra info in the console. It happens on some examples on my repo https://github.com/cedricpinson/osgjs but if I extract the shader that does not optimize and put it in your web interface it works. So it looks that after different call, something happens inside the optimizer.

Any clue ?

[zz85]

Hi @cedricpinson, it's been awhile since I've used this so I don't remember why that happens off from my head, although I'm guessing it could be a memory issue or probably some bugs that yield strange behaviour.

Anyways, I tried loading http://osgjs.org/examples/pbr/?GLSLOptimizer=1&log=info but I don't seem to see the error that you're describing?

[Nolesh]

Hi @zz85, it happens when a shader contains some errors. Instead of showing them (sometimes it shows the error), it returns unreadable or Chinese symbols. My steps to reproduce an error:

1. Choose Fragment shader & OpenGL ES 3.0
2. Copy and paste the source code below.
3. Click on the Optimize! button. At first time it should show an error.
4. Correct the error (float x = 1.0;)
5. Click on the Optimize! button again. It optimizes the code.
6. Repeat steps 2 and 3 and you will get an unexpected result!

Source code:

uniform sampler2D u_texture;
uniform vec2 u_res;

void main(void)
{	
   vec2 texCoord = gl_FragCoord.xy / u_res.xy;
   float x = 1; //error (must be 1.0)    

   vec4 sceneColor = texture2D(u_texture, texCoord);	
	
   if(sceneColor.r<1. && sceneColor.g<1. && sceneColor.b<1.) discard;
   gl_FragColor = sceneColor;	
}

[danbriggs5]

Just checking to see if there's been any updates on this in the last few months? Seeing this as well.

[danbriggs5]

Just wanted to note that it's possible to get around this by modifying the minified file a little bit (glsl-optimizer.js).

You should be able to wrap all the code with a function so it gets re-initialized each time you call it. Then you don't need to worry about some kind of internal memory causing this issue on subsequent calls.

For example:

module.exports = () => {
    // Paste all the existing code in the file
    return Module;
};

Then you'll also need to comment out the existing export. ie, search for module["exports"]=Module and replace it with /*module["exports"]=Module*/.

Note that you'll need to use it slightly differently now that it's a function of course.

Is this ideal? Definitely not. But it should work in a pinch if you absolutely need to get around this error.

I'm using a slightly different version of the library so can't promise these exact steps will get it working, but should give you something to go on.