glsl compile error with GLSL ES 3.00

[eyworldwide]

Describe the bug I think it's a glsl code compile bug. Support for GLSL ES 3.00 is not very good.

To Reproduce

The source code of frag shader:

precision highp float;

in vec4 vColor;
in vec2 vPosition;
out vec4 fragColor;

void main () {
  float A = -dot(vPosition, vPosition);
  if (A < -4.0) discard;
  float B = exp(A) * vColor.a;
  fragColor = vec4(B * vColor.rgb, B);
}

The ShaderFactory.convertTo300 method converts the code to:

  #version 300 es
  #define GRAPHICS_API_WEBGL2
....

 precision highp float;

 in vec4 vColor;
 in vec2 vPosition;
 out vec4 fragColor;

 // This line is NOT I expect:
 out vec4 glFragColor;

 void main() {
   float A = -dot(vPosition, vPosition);
   if (A < -4.0) discard;
   float B = exp(A) * vColor.a;
   fragColor = vec4(B * vColor.rgb, B);
 }

Screenshots

Expected behavior

1. Keep the GLSL ES 3.00 code unchanged. OR
2. Covert to a lower version can compile.

Perhaps giving the user the option to choose would be a wise decision.

PS: String replacement is an unsafe approach for handling GLSL syntax. But I have no idea if there's a better approach to solve the problem.

[zhuxudong]

current compile workflow:

will case some problom:

• glsl300 -> webgl1.0 will cause error
• glsl300 -> webgl2.0 will cause error in some grammar

maybe the final solution?

[eyworldwide]

@zhuxudong @Sway007 I think WebGPU should also be taken into consideration. This is the way to ensure that our architecture is future-proof.

flowchart LR
shaderLab --> AST{AST Compile};
AST --WebGL2--> GLSL300;
AST --WebGL1--> GLSL100;
AST --WebGPU--> WGSL;

@zhuxudong For now, you just need to apply a quick patch.

[zhuxudong]

@zhuxudong @Sway007 I think WebGPU should also be taken into consideration. This is the way to ensure that our architecture is future-proof.

flowchart LR
shaderLab --> AST{AST Compile};
AST --WebGL2--> GLSL300;
AST --WebGL1--> GLSL100;
AST --WebGPU--> WGSL;

@zhuxudong For now, you just need to apply a quick patch.

yes，the source of the AST is not only the shaderLab, such as you original glsl100 or glsl300 or wgsl, I don't know if we should consider this

[eyworldwide]

yes，the source of the AST is not only the shaderLab, such as you original glsl100 or glsl300 or wgsl, I don't know if we should consider this

I think choosing to establish a standard language is a better option. It makes no sense to support such a wide array of syntaxes. These languages should serve as compiled outputs, rather than inputs.