nuclear@31: #include <math.h>
nuclear@30: #include <algorithm>
nuclear@2: #include "brdf.h"
nuclear@31: #include "material.h"
nuclear@2: #include "erebus_impl.h"
nuclear@2: 
nuclear@31: // --- class SurfaceGeometry ---
nuclear@31: SurfaceGeometry::SurfaceGeometry(const Vector3 &norm, VecLength st)
nuclear@31: 	: SurfaceGeometry(norm, Vector2(0, 0), st)
nuclear@31: {
nuclear@31: }
nuclear@31: 
nuclear@31: SurfaceGeometry::SurfaceGeometry(const Vector3 &norm, const Vector2 &uvarg, VecLength st)
nuclear@31: 	: normal(norm), uv(uvarg)
nuclear@31: {
nuclear@31: 	if(st == unknown) {
nuclear@31: 		normal.normalize();
nuclear@31: 	}
nuclear@31: 
nuclear@31: 	tangent = Vector3(1.0f, 0.0f, 0.0f);
nuclear@34: 	if(1.0 - fabs(dot_product(normal, tangent)) < 1e-4f) {
nuclear@31: 		tangent = Vector3(0.0f, 0.0f, 1.0f);
nuclear@31: 	}
nuclear@31: 	Vector3 bitan = cross_product(normal, tangent);
nuclear@31: 	tangent = cross_product(bitan, normal);
nuclear@31: }
nuclear@31: 
nuclear@31: SurfaceGeometry::SurfaceGeometry(const Vector3 &norm, const Vector3 &tang, VecLength st)
nuclear@31: 	: SurfaceGeometry(norm, tang, Vector2(0, 0), st)
nuclear@31: {
nuclear@31: }
nuclear@31: 
nuclear@31: SurfaceGeometry::SurfaceGeometry(const Vector3 &norm, const Vector3 &tang, const Vector2 &uvarg, VecLength st)
nuclear@31: 	: normal(norm), tangent(tang), uv(uvarg)
nuclear@31: {
nuclear@31: 	if(st == unknown) {
nuclear@31: 		normal.normalize();
nuclear@31: 		tangent.normalize();
nuclear@31: 	}
nuclear@31: }
nuclear@31: 
nuclear@31: Vector3 SurfaceGeometry::spherical_to_world(float theta, float phi) const
nuclear@31: {
nuclear@31: 	float x = cos(theta) * sin(phi);
nuclear@31: 	float y = sin(theta) * sin(phi);
nuclear@31: 	float z = cos(phi);
nuclear@31: 	return sample_to_world(Vector3(x, y, z));
nuclear@31: }
nuclear@31: 
nuclear@31: Vector3 SurfaceGeometry::sample_to_world(const Vector3 &v) const
nuclear@31: {
nuclear@31: 	Matrix3x3 xform;
nuclear@31: 	xform.set_column_vector(tangent, 0);
nuclear@31: 	xform.set_column_vector(cross_product(normal, tangent), 1);
nuclear@31: 	xform.set_column_vector(normal, 2);
nuclear@31: 	return v.transformed(xform);
nuclear@31: }
nuclear@31: 
nuclear@31: Vector3 SurfaceGeometry::world_to_sample(const Vector3 &v) const
nuclear@31: {
nuclear@31: 	Matrix3x3 xform;
nuclear@31: 	xform.set_row_vector(tangent, 0);
nuclear@31: 	xform.set_row_vector(cross_product(normal, tangent), 1);
nuclear@31: 	xform.set_row_vector(normal, 2);
nuclear@31: 	return v.transformed(xform);
nuclear@31: }
nuclear@31: 
nuclear@2: // ---- class Reflectance ----
nuclear@2: Reflectance::Reflectance()
nuclear@2: {
nuclear@31: 	mtl = 0;
nuclear@2: }
nuclear@2: 
nuclear@31: Reflectance::Reflectance(const Material *mtl)
nuclear@2: {
nuclear@31: 	this->mtl = mtl;
nuclear@31: }
nuclear@31: 
nuclear@31: float Reflectance::sample(const SurfaceGeometry &geom, const Vector3 &outdir, Vector3 *indir) const
nuclear@31: {
nuclear@31: 	*indir = sample_dir(geom, outdir);
nuclear@31: 	return eval(geom, outdir, *indir);
nuclear@2: }
nuclear@2: 
nuclear@21: // --- class CompositeRefl ----
nuclear@21: CompositeRefl::CompositeRefl()
nuclear@21: {
nuclear@21: 	valid_checked = false;
nuclear@21: }
nuclear@21: 
nuclear@31: CompositeRefl::CompositeRefl(const Material *mtl)
nuclear@31: 	: Reflectance(mtl)
nuclear@31: {
nuclear@31: 	valid_checked = false;
nuclear@31: }
nuclear@31: 
nuclear@31: int CompositeRefl::pick_brdf(const SurfaceGeometry &geom, const Vector3 &outdir) const
nuclear@21: {
nuclear@21: 	if(sub_brdf.empty()) {
nuclear@21: 		return -1;
nuclear@21: 	}
nuclear@21: 
nuclear@21: 	int brdf_count = (int)sub_brdf.size();
nuclear@21: 	if(brdf_count == 1) {
nuclear@21: 		return 0;
nuclear@21: 	}
nuclear@21: 
nuclear@21: 	// construct CDF from sub-brdf probabilities
nuclear@21: 	float *cdf = (float*)alloca(brdf_count * sizeof *cdf);
nuclear@21: 	for(int i=0; i<brdf_count; i++) {
nuclear@21: 		const SubRefl &sub = sub_brdf[i];
nuclear@31: 		float w = sub.weight_func ? sub.weight_func(geom, outdir) : sub.weight;
nuclear@21: 		cdf[i] = i > 0 ? cdf[i - 1] + w : w;
nuclear@21: 	}
nuclear@21: 
nuclear@21: 	float rval = randf(0.0, cdf[brdf_count - 1]);
nuclear@21: 	for(int i=0; i<brdf_count - 1; i++) {
nuclear@21: 		if(rval <= cdf[i]) return i;
nuclear@21: 	}
nuclear@21: 	return brdf_count - 1;
nuclear@21: }
nuclear@21: 
nuclear@21: void CompositeRefl::add_brdf(Reflectance *brdf, float weight)
nuclear@21: {
nuclear@21: 	SubRefl sub;
nuclear@21: 	sub.brdf = brdf;
nuclear@21: 	sub.weight = weight;
nuclear@21: 	sub.weight_func = 0;
nuclear@21: 	sub_brdf.push_back(sub);
nuclear@21: 
nuclear@21: 	valid_checked = false;
nuclear@21: }
nuclear@21: 
nuclear@21: void CompositeRefl::add_brdf(Reflectance *brdf, CompReflWeightFunc weight_func)
nuclear@21: {
nuclear@21: 	SubRefl sub;
nuclear@21: 	sub.brdf = brdf;
nuclear@21: 	sub.weight = 0.0;
nuclear@21: 	sub.weight_func = weight_func;
nuclear@21: 	sub_brdf.push_back(sub);
nuclear@21: 
nuclear@21: 	valid_checked = false;
nuclear@21: }
nuclear@21: 
nuclear@21: bool CompositeRefl::check_valid() const
nuclear@21: {
nuclear@21: 	float sum = 0.0;
nuclear@21: 	for(size_t i=0; i<sub_brdf.size(); i++) {
nuclear@21: 		if(!sub_brdf[i].weight_func) {
nuclear@21: 			sum += sub_brdf[i].weight;
nuclear@21: 		}
nuclear@21: 	}
nuclear@21: 	return sum < 1.0001;
nuclear@21: }
nuclear@21: 
nuclear@21: static bool warned_composite_usage;
nuclear@21: static const char *composite_usage_warnstr =
nuclear@21: 	"warning: don't call CompositeRefl's sample_dir and eval separately\n"
nuclear@21: 	"         it'll pick different brdfs each time! use sample instead\n";
nuclear@21: 
nuclear@31: Vector3 CompositeRefl::sample_dir(const SurfaceGeometry &geom, const Vector3 &outdir) const
nuclear@21: {
nuclear@21: 	if(!warned_composite_usage) {
nuclear@21: 		fputs(composite_usage_warnstr, stderr);
nuclear@21: 		warned_composite_usage = true;
nuclear@21: 	}
nuclear@31: 	int bidx = pick_brdf(geom, outdir);
nuclear@31: 	return sub_brdf[bidx].brdf->sample_dir(geom, outdir);
nuclear@21: }
nuclear@21: 
nuclear@31: float CompositeRefl::sample(const SurfaceGeometry &geom, const Vector3 &outdir, Vector3 *indir) const
nuclear@21: {
nuclear@31: 	int bidx = pick_brdf(geom, outdir);
nuclear@31: 	return sub_brdf[bidx].brdf->sample(geom, outdir, indir);
nuclear@21: }
nuclear@21: 
nuclear@31: float CompositeRefl::eval(const SurfaceGeometry &geom, const Vector3 &outdir, const Vector3 &indir) const
nuclear@21: {
nuclear@21: 	if(!warned_composite_usage) {
nuclear@21: 		fputs(composite_usage_warnstr, stderr);
nuclear@21: 		warned_composite_usage = true;
nuclear@21: 	}
nuclear@31: 	int bidx = pick_brdf(geom, outdir);
nuclear@31: 	return sub_brdf[bidx].brdf->eval(geom, outdir, indir);
nuclear@21: }
nuclear@21: 
nuclear@2: // --- class LambertRefl ---
nuclear@31: Vector3 LambertRefl::sample_dir(const SurfaceGeometry &geom, const Vector3 &outdir) const
nuclear@2: {
nuclear@32: 	// TODO: write a better uniform disk sampling that doesn't rely in rejection
nuclear@32: 	Vector3 dir;
nuclear@32: 	do {
nuclear@32: 		dir = Vector3(randf(-1, 1), randf(-1, 1), 0);
nuclear@32: 	} while(dir.length_sq() > 1.0);
nuclear@32: 	dir.z = sqrt(1.0 - (dir.x * dir.x + dir.y * dir.y));
nuclear@32: 
nuclear@32: 	return geom.sample_to_world(dir);
nuclear@2: }
nuclear@2: 
nuclear@31: float LambertRefl::eval(const SurfaceGeometry &geom, const Vector3 &outdir, const Vector3 &indir) const
nuclear@2: {
nuclear@31: 	return dot_product(geom.normal, outdir);
nuclear@2: }
nuclear@21: 
nuclear@21: // --- class MirrorRefl ---
nuclear@31: Vector3 MirrorRefl::sample_dir(const SurfaceGeometry &geom, const Vector3 &outdir) const
nuclear@21: {
nuclear@31: 	return outdir.reflection(geom.normal);
nuclear@21: }
nuclear@21: 
nuclear@31: float MirrorRefl::eval(const SurfaceGeometry &geom, const Vector3 &outdir, const Vector3 &indir) const
nuclear@21: {
nuclear@21: 	return 1.0f;
nuclear@21: }
nuclear@28: 
nuclear@28: // --- class PhongRefl ---
nuclear@31: Vector3 PhongRefl::sample_dir(const SurfaceGeometry &geom, const Vector3 &outdir) const
nuclear@28: {
nuclear@31: 	Vector3 refl = outdir.reflection(geom.normal).normalized();
nuclear@31: 	SurfaceGeometry refl_geom(refl, SurfaceGeometry::unit);
nuclear@28: 
nuclear@31: 	float shininess = mtl ? mtl->get_attrib_value("shininess", geom.uv.x, geom.uv.y) : 42.0;
nuclear@28: 
nuclear@28: 	float phi = acos(pow(randf(), 1.0 / (shininess + 1)));
nuclear@28: 	float theta = 2.0 * M_PI * randf();
nuclear@28: 
nuclear@31: 	return refl_geom.spherical_to_world(theta, phi);
nuclear@28: }
nuclear@28: 
nuclear@31: float PhongRefl::eval(const SurfaceGeometry &geom, const Vector3 &outdir, const Vector3 &indir) const
nuclear@28: {
nuclear@31: 	float shininess = mtl ? mtl->get_attrib_value("shininess", geom.uv.x, geom.uv.y) : 42.0;
nuclear@31: 
nuclear@31: 	Vector3 refl = outdir.reflection(geom.normal);
nuclear@28: 	float dot = std::max<float>(dot_product(indir, refl), 0.0f);
nuclear@28: 	return pow(dot, shininess);
nuclear@28: }