1.1 --- a/liberebus/src/brdf.cc	Tue May 27 07:49:09 2014 +0300
     1.2 +++ b/liberebus/src/brdf.cc	Wed May 28 07:06:29 2014 +0300
     1.3 @@ -12,6 +12,102 @@
     1.4  	return eval(norm, outdir, *indir);
     1.5  }
     1.6  
     1.7 +// --- class CompositeRefl ----
     1.8 +CompositeRefl::CompositeRefl()
     1.9 +{
    1.10 +	valid_checked = false;
    1.11 +}
    1.12 +
    1.13 +int CompositeRefl::pick_brdf(const Vector3 &norm, const Vector3 &outdir) const
    1.14 +{
    1.15 +	if(sub_brdf.empty()) {
    1.16 +		return -1;
    1.17 +	}
    1.18 +
    1.19 +	int brdf_count = (int)sub_brdf.size();
    1.20 +	if(brdf_count == 1) {
    1.21 +		return 0;
    1.22 +	}
    1.23 +
    1.24 +	// construct CDF from sub-brdf probabilities
    1.25 +	float *cdf = (float*)alloca(brdf_count * sizeof *cdf);
    1.26 +	for(int i=0; i<brdf_count; i++) {
    1.27 +		const SubRefl &sub = sub_brdf[i];
    1.28 +		float w = sub.weight_func ? sub.weight_func(norm, outdir) : sub.weight;
    1.29 +		cdf[i] = i > 0 ? cdf[i - 1] + w : w;
    1.30 +	}
    1.31 +
    1.32 +	float rval = randf(0.0, cdf[brdf_count - 1]);
    1.33 +	for(int i=0; i<brdf_count - 1; i++) {
    1.34 +		if(rval <= cdf[i]) return i;
    1.35 +	}
    1.36 +	return brdf_count - 1;
    1.37 +}
    1.38 +
    1.39 +void CompositeRefl::add_brdf(Reflectance *brdf, float weight)
    1.40 +{
    1.41 +	SubRefl sub;
    1.42 +	sub.brdf = brdf;
    1.43 +	sub.weight = weight;
    1.44 +	sub.weight_func = 0;
    1.45 +	sub_brdf.push_back(sub);
    1.46 +
    1.47 +	valid_checked = false;
    1.48 +}
    1.49 +
    1.50 +void CompositeRefl::add_brdf(Reflectance *brdf, CompReflWeightFunc weight_func)
    1.51 +{
    1.52 +	SubRefl sub;
    1.53 +	sub.brdf = brdf;
    1.54 +	sub.weight = 0.0;
    1.55 +	sub.weight_func = weight_func;
    1.56 +	sub_brdf.push_back(sub);
    1.57 +
    1.58 +	valid_checked = false;
    1.59 +}
    1.60 +
    1.61 +bool CompositeRefl::check_valid() const
    1.62 +{
    1.63 +	float sum = 0.0;
    1.64 +	for(size_t i=0; i<sub_brdf.size(); i++) {
    1.65 +		if(!sub_brdf[i].weight_func) {
    1.66 +			sum += sub_brdf[i].weight;
    1.67 +		}
    1.68 +	}
    1.69 +	return sum < 1.0001;
    1.70 +}
    1.71 +
    1.72 +static bool warned_composite_usage;
    1.73 +static const char *composite_usage_warnstr =
    1.74 +	"warning: don't call CompositeRefl's sample_dir and eval separately\n"
    1.75 +	"         it'll pick different brdfs each time! use sample instead\n";
    1.76 +
    1.77 +Vector3 CompositeRefl::sample_dir(const Vector3 &norm, const Vector3 &outdir) const
    1.78 +{
    1.79 +	if(!warned_composite_usage) {
    1.80 +		fputs(composite_usage_warnstr, stderr);
    1.81 +		warned_composite_usage = true;
    1.82 +	}
    1.83 +	int bidx = pick_brdf(norm, outdir);
    1.84 +	return sub_brdf[bidx].brdf->sample_dir(norm, outdir);
    1.85 +}
    1.86 +
    1.87 +float CompositeRefl::sample(const Vector3 &norm, const Vector3 &outdir, Vector3 *indir) const
    1.88 +{
    1.89 +	int bidx = pick_brdf(norm, outdir);
    1.90 +	return sub_brdf[bidx].brdf->sample(norm, outdir, indir);
    1.91 +}
    1.92 +
    1.93 +float CompositeRefl::eval(const Vector3 &norm, const Vector3 &outdir, const Vector3 &indir) const
    1.94 +{
    1.95 +	if(!warned_composite_usage) {
    1.96 +		fputs(composite_usage_warnstr, stderr);
    1.97 +		warned_composite_usage = true;
    1.98 +	}
    1.99 +	int bidx = pick_brdf(norm, outdir);
   1.100 +	return sub_brdf[bidx].brdf->eval(norm, outdir, indir);
   1.101 +}
   1.102 +
   1.103  // --- class LambertRefl ---
   1.104  Vector3 LambertRefl::sample_dir(const Vector3 &norm, const Vector3 &outdir) const
   1.105  {
   1.106 @@ -23,3 +119,14 @@
   1.107  {
   1.108  	return dot_product(norm, outdir);
   1.109  }
   1.110 +
   1.111 +// --- class MirrorRefl ---
   1.112 +Vector3 MirrorRefl::sample_dir(const Vector3 &norm, const Vector3 &outdir) const
   1.113 +{
   1.114 +	return outdir.reflection(norm);
   1.115 +}
   1.116 +
   1.117 +float MirrorRefl::eval(const Vector3 &norm, const Vector3 &outdir, const Vector3 &indir) const
   1.118 +{
   1.119 +	return 1.0f;
   1.120 +}