`#define` nested in function body produces parse error

[mitchmindtree]

I just attempted to parse a large collection of test shaders, and they all worked beautifully, except one!

Here's the culprit in its entirey:

/*{
    "CATEGORIES": [
        "Dissolve"
    ],
    "CREDIT": "Automatically converted from https://www.github.com/gl-transitions/gl-transitions/tree/master/FilmBurn.glsl",
    "DESCRIPTION": "",
    "INPUTS": [
        {
            "NAME": "startImage",
            "TYPE": "image"
        },
        {
            "NAME": "endImage",
            "TYPE": "image"
        },
        {
            "DEFAULT": 0,
            "MAX": 1,
            "MIN": 0,
            "NAME": "progress",
            "TYPE": "float"
        },
        {
            "DEFAULT": 2.31,
            "MAX": 10,
            "MIN": 0,
            "NAME": "Seed",
            "TYPE": "float"
        }
    ],
    "ISFVSN": "2"
}
*/



vec4 getFromColor(vec2 inUV)	{
	return IMG_NORM_PIXEL(startImage, inUV);
}
vec4 getToColor(vec2 inUV)	{
	return IMG_NORM_PIXEL(endImage, inUV);
}



// author: Anastasia Dunbar
// license: MIT
float sigmoid(float x, float a) {
    float b = pow(x*2.,a)/2.;
    if (x > .5) {
        b = 1.-pow(2.-(x*2.),a)/2.;
    }
	return b;
}
float rand(float co){
    return fract(sin((co*24.9898)+Seed)*43758.5453);
}
float rand(vec2 co){
    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}
float apow(float a,float b) { return pow(abs(a),b)*sign(b); }
vec3 pow3(vec3 a,vec3 b) { return vec3(apow(a.r,b.r),apow(a.g,b.g),apow(a.b,b.b)); }
float smooth_mix(float a,float b,float c) { return mix(a,b,sigmoid(c,2.)); }
float random(vec2 co, float shft){
    co += 10.;
    return smooth_mix(fract(sin(dot(co.xy ,vec2(12.9898+(floor(shft)*.5),78.233+Seed))) * 43758.5453),fract(sin(dot(co.xy ,vec2(12.9898+(floor(shft+1.)*.5),78.233+Seed))) * 43758.5453),fract(shft));
}
float smooth_random(vec2 co, float shft) {
	return smooth_mix(smooth_mix(random(floor(co),shft),random(floor(co+vec2(1.,0.)),shft),fract(co.x)),smooth_mix(random(floor(co+vec2(0.,1.)),shft),random(floor(co+vec2(1.,1.)),shft),fract(co.x)),fract(co.y));
}
vec4 texture(vec2 p) {
    return mix(getFromColor(p), getToColor(p), sigmoid(progress,10.));
}
#define pi 3.14159265358979323
#define clamps(x) clamp(x,0.,1.)

vec4 transition(vec2 p) {
  vec3 f = vec3(0.);
  for (float i = 0.; i < 13.; i++) {
    f += sin(((p.x*rand(i)*6.)+(progress*8.))+rand(i+1.43))*sin(((p.y*rand(i+4.4)*6.)+(progress*6.))+rand(i+2.4));
    f += 1.-clamps(length(p-vec2(smooth_random(vec2(progress*1.3),i+1.),smooth_random(vec2(progress*.5),i+6.25)))*mix(20.,70.,rand(i)));
  }
  f += 4.;
  f /= 11.;
  f = pow3(f*vec3(1.,0.7,0.6),vec3(1.,2.-sin(progress*pi),1.3));
  f *= sin(progress*pi);
  
  p -= .5;
  p *= 1.+(smooth_random(vec2(progress*5.),6.3)*sin(progress*pi)*.05);
  p += .5;
  
  vec4 blurred_image = vec4(0.);
  float bluramount = sin(progress*pi)*.03;
  #define repeats  50.
  for (float i = 0.; i < repeats; i++) { 
      vec2 q = vec2(cos(degrees((i/repeats)*360.)),sin(degrees((i/repeats)*360.))) *  (rand(vec2(i,p.x+p.y))+bluramount); 
      vec2 uv2 = p+(q*bluramount);
      blurred_image += texture(uv2);
  }
  blurred_image /= repeats;
  
  return blurred_image+vec4(f,0.);
}



void main()	{
	gl_FragColor = transition(isf_FragNormCoord.xy);
}

The panic provides the following error:

thread 'test_gen_glsl' panicked at 'err while parsing glsl /home/mindtree/programming/rust/nannou_isf/test_files/Film Burn.fs: error: 0: at line 94:
  #define repeats  50.                                                                                                                        
  ^                                                                                                                                           
expected '}', found #                                                                                                                         
                                                                                                                                              
', tests/gen_glsl.rs:23:35                                             

This refers to the #define in the transition function towards the bottom.

I'm unsure - are nested #defines like this even officially supported as a part of GLSL? I haven't seem them before. That said, this shader is one of the standard shaders provided with VDMX (quite a popular VJ application), so I guess there's at least one GLSL parser out there that does support it.

[hadronized]

Yeah… not supported so far. 😢

I need to find a better way to represent and parse CPP directives. Right now, they work because I represent them as part of the AST, but they should be implemented cross AST. I’m still looking for ideas and ways to do that efficiently.

[hadronized]

#define are supported at the global space, though. But I definitely want a better CPP representation to support all possible cases.

[hadronized]

@mitchmindtree may I ask where those examples can be found? I’d love to integrate them to glsl as part of the integration test suite!

[mitchmindtree]

Thanks for the update! And no worries, I have no qualms with moving the defines to the global space 👍

You can find those shaders at the Vidvox repo here.

[hadronized]

I’m working on the preprocessor issue. :)

[pema99]

Is there any news on this?