mitsuba/src/emitters/spot.cpp

327 lines
12 KiB
C++

/*
This file is part of Mitsuba, a physically based rendering system.
Copyright (c) 2007-2012 by Wenzel Jakob and others.
Mitsuba is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License Version 3
as published by the Free Software Foundation.
Mitsuba is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <mitsuba/render/scene.h>
#include <mitsuba/hw/basicshader.h>
MTS_NAMESPACE_BEGIN
/*!\plugin{spot}{Spot light source}
* \icon{emitter_spot}
* \order{3}
* \parameters{
* \parameter{toWorld}{\Transform\Or\Animation}{
* Specifies an optional sensor-to-world transformation.
* \default{none (i.e. sensor space $=$ world space)}
* }
* \parameter{intensity}{\Spectrum}{
* Specifies the maximum radiant intensity at the center
* in units of power per unit steradian.
* \default{1}
* }
* \parameter{cutoffAngle}{\Float}{Cutoff angle, beyond which the spot light is completely black \default{\code{20} degrees}}
* \parameter{beamWidth}{\Float}{Subtended angle of the central beam portion \default{\code{cutoffAngle}$\ \cdot\ \nicefrac 34$}}
* \parameter{texture}{\Texture}{
* An optional texture to be projected along the spot light
* }
* \parameter{samplingWeight}{\Float}{
* Specifies the relative amount of samples
* allocated to this emitter. \default{1}
* }
* }
*
* This plugin provides a spot light with a linear falloff.
* In its local coordinate system, the spot light is positioned at the origin
* and points along the positive Z direction. It can be conveniently
* reoriented using the \code{lookat} tag, e.g.:
* \begin{xml}
* <emitter type="spot">
* <transform name="toWorld">
* <!-- Orient the light so that points from (1, 1, 1) towards (1, 2, 1) -->
* <lookat origin="1, 1, 1" target="1, 2, 1"/>
* </transform>
* </emitter>
* \end{xml}
*
* The intensity linearly ramps up from \code{cutoffAngle}
* to \code{beamWidth} (both specified in degrees), after which it remains at
* the maximum value. A projection texture may optionally be supplied.
*/
class SpotEmitter : public Emitter {
public:
SpotEmitter(const Properties &props) : Emitter(props) {
m_intensity = props.getSpectrum("intensity", Spectrum(1.0f));
m_cutoffAngle = props.getFloat("cutoffAngle", 20);
m_beamWidth = props.getFloat("beamWidth", m_cutoffAngle * 3.0f/4.0f);
m_beamWidth = degToRad(m_beamWidth);
m_cutoffAngle = degToRad(m_cutoffAngle);
Assert(m_cutoffAngle >= m_beamWidth);
m_type = EDeltaPosition;
m_texture = new ConstantSpectrumTexture(
props.getSpectrum("texture", Spectrum(1.0f)));
}
SpotEmitter(Stream *stream, InstanceManager *manager)
: Emitter(stream, manager) {
m_texture = static_cast<Texture *>(manager->getInstance(stream));
m_intensity = Spectrum(stream);
m_beamWidth = stream->readFloat();
m_cutoffAngle = stream->readFloat();
configure();
}
void configure() {
m_cosBeamWidth = std::cos(m_beamWidth);
m_cosCutoffAngle = std::cos(m_cutoffAngle);
m_uvFactor = std::tan(m_cutoffAngle);
m_invTransitionWidth = 1.0f / (m_cutoffAngle - m_beamWidth);
}
void serialize(Stream *stream, InstanceManager *manager) const {
Emitter::serialize(stream, manager);
manager->serialize(stream, m_texture.get());
m_intensity.serialize(stream);
stream->writeFloat(m_beamWidth);
stream->writeFloat(m_cutoffAngle);
}
inline Spectrum falloffCurve(const Vector &d) const {
const Float cosTheta = Frame::cosTheta(d);
if (cosTheta <= m_cosCutoffAngle)
return Spectrum(0.0f);
Spectrum result(1.0f);
if (m_texture->getClass() != MTS_CLASS(ConstantSpectrumTexture)) {
Intersection its;
its.hasUVPartials = false;
its.uv = Point2(0.5f + 0.5f * d.x / (d.z * m_uvFactor),
0.5f + 0.5f * d.y / (d.z * m_uvFactor));
result = m_texture->eval(its);
}
if (cosTheta >= m_cosBeamWidth)
return result;
return result * ((m_cutoffAngle - std::acos(cosTheta))
* m_invTransitionWidth);
}
Spectrum samplePosition(PositionSamplingRecord &pRec, const Point2 &sample,
const Point2 *extra) const {
const Transform &trafo = m_worldTransform->eval(pRec.time);
pRec.p = trafo.transformAffine(Point(0.0f));
pRec.n = Normal(0.0f);
pRec.pdf = 1.0f;
pRec.measure = EDiscrete;
return m_intensity * (4 * M_PI);
}
Spectrum evalPosition(const PositionSamplingRecord &pRec) const {
return (pRec.measure == EDiscrete) ? (m_intensity * 4*M_PI) : Spectrum(0.0f);
}
Float pdfPosition(const PositionSamplingRecord &pRec) const {
return (pRec.measure == EDiscrete) ? 1.0f : 0.0f;
}
Spectrum sampleDirection(DirectionSamplingRecord &dRec,
PositionSamplingRecord &pRec,
const Point2 &sample,
const Point2 *extra) const {
const Transform &trafo = m_worldTransform->eval(pRec.time);
Vector d = Warp::squareToUniformCone(m_cosCutoffAngle, sample);
dRec.d = trafo(d);
dRec.pdf = Warp::squareToUniformConePdf(m_cosCutoffAngle);
dRec.measure = ESolidAngle;
return evalDirection(dRec, pRec)/dRec.pdf;
}
Float pdfDirection(const DirectionSamplingRecord &dRec,
const PositionSamplingRecord &pRec) const {
return (dRec.measure == ESolidAngle) ? Warp::squareToUniformConePdf(m_cosCutoffAngle) : 0.0f;
}
Spectrum evalDirection(const DirectionSamplingRecord &dRec,
const PositionSamplingRecord &pRec) const {
const Transform &trafo = m_worldTransform->eval(pRec.time);
return (dRec.measure == ESolidAngle) ?
falloffCurve(trafo.inverse()(dRec.d)) * INV_FOURPI : Spectrum(0.0f);
}
Spectrum sampleRay(Ray &ray,
const Point2 &spatialSample,
const Point2 &directionalSample,
Float time) const {
const Transform &trafo = m_worldTransform->eval(time);
Vector local = Warp::squareToUniformCone(
m_cosCutoffAngle, directionalSample);
ray.setTime(time);
ray.setOrigin(trafo.transformAffine(Point(0.0f)));
ray.setDirection(trafo(local));
Float dirPdf = Warp::squareToUniformConePdf(m_cosCutoffAngle);
return m_intensity * falloffCurve(local) / dirPdf;
}
Spectrum sampleDirect(DirectSamplingRecord &dRec, const Point2 &sample) const {
const Transform &trafo = m_worldTransform->eval(dRec.time);
dRec.p = trafo.transformAffine(Point(0.0f));
dRec.pdf = 1.0f;
dRec.measure = EDiscrete;
dRec.uv = Point2(0.5f);
dRec.d = dRec.p - dRec.ref;
dRec.dist = dRec.d.length();
Float invDist = 1.0f / dRec.dist;
dRec.d *= invDist;
dRec.n = Normal(0.0f);
dRec.pdf = 1;
dRec.measure = EDiscrete;
return m_intensity * falloffCurve(trafo.inverse()(-dRec.d)) * (invDist * invDist);
}
Float pdfDirect(const DirectSamplingRecord &dRec) const {
return dRec.measure == EDiscrete ? 1.0f : 0.0f;
}
void addChild(const std::string &name, ConfigurableObject *child) {
if (child->getClass()->derivesFrom(MTS_CLASS(Texture)) && name == "texture") {
m_texture = static_cast<Texture *>(child);
} else {
Emitter::addChild(name, child);
}
}
AABB getAABB() const {
return m_worldTransform->getTranslationBounds();
}
std::string toString() const {
std::ostringstream oss;
oss << "SpotEmitter[" << std::endl
<< " intensity = " << m_intensity.toString() << "," << std::endl
<< " texture = " << m_texture.toString() << "," << std::endl
<< " beamWidth = " << (m_beamWidth * 180/M_PI) << "," << std::endl
<< " cutoffAngle = " << (m_cutoffAngle * 180/M_PI) << std::endl
<< "]";
return oss.str();
}
Shader *createShader(Renderer *renderer) const;
MTS_DECLARE_CLASS()
private:
Spectrum m_intensity;
ref<Texture> m_texture;
Float m_beamWidth, m_cutoffAngle, m_uvFactor;
Float m_cosBeamWidth, m_cosCutoffAngle, m_invTransitionWidth;
};
// ================ Hardware shader implementation ================
class SpotEmitterShader : public Shader {
public:
SpotEmitterShader(Renderer *renderer, Transform worldToEmitter,
Float invTransitionWidth, Float cutoffAngle, Float cosCutoffAngle,
Float cosBeamWidth, Float uvFactor, const Texture *texture)
: Shader(renderer, EEmitterShader), m_worldToEmitter(worldToEmitter),
m_invTransitionWidth(invTransitionWidth), m_cutoffAngle(cutoffAngle),
m_cosCutoffAngle(cosCutoffAngle), m_cosBeamWidth(cosBeamWidth),
m_uvFactor(uvFactor), m_texture(texture) {
m_textureShader = renderer->registerShaderForResource(m_texture.get());
}
bool isComplete() const {
return m_textureShader.get() != NULL;
}
void cleanup(Renderer *renderer) {
renderer->unregisterShaderForResource(m_texture.get());
}
void putDependencies(std::vector<Shader *> &deps) {
deps.push_back(m_textureShader.get());
}
void generateCode(std::ostringstream &oss, const std::string &evalName,
const std::vector<std::string> &depNames) const {
oss << "uniform float " << evalName << "_invTransitionWidth;" << endl
<< "uniform float " << evalName << "_cutoffAngle;" << endl
<< "uniform float " << evalName << "_cosCutoffAngle;" << endl
<< "uniform float " << evalName << "_cosBeamWidth;" << endl
<< "uniform float " << evalName << "_uvFactor;" << endl
<< "uniform mat4 " << evalName << "_worldToEmitter;" << endl
<< "vec3 " << evalName << "_dir(vec3 wo) {" << endl
<< " vec3 localDir = (" << evalName << "_worldToEmitter * vec4(wo, 0)).xyz;" << endl
<< " float cosTheta = localDir.z;" << endl
<< " if (cosTheta < " << evalName << "_cosCutoffAngle)" << endl
<< " return vec3(0.0);" << endl
<< " vec2 uv = 0.5 + 0.5 * (localDir.xy / (localDir.z * " << evalName << "_uvFactor));" << endl
<< " vec3 color = " << depNames[0] << "(uv) * inv_fourpi;" << endl
<< " if (cosTheta > " << evalName << "_cosBeamWidth)" << endl
<< " return color;" << endl
<< " return color * ((" << evalName << "_cutoffAngle - acos(cosTheta))" << endl
<< " * " << evalName << "_invTransitionWidth);" << endl
<< "}" << endl;
}
void resolve(const GPUProgram *program, const std::string &evalName, std::vector<int> &parameterIDs) const {
parameterIDs.push_back(program->getParameterID(evalName + "_worldToEmitter", false));
parameterIDs.push_back(program->getParameterID(evalName + "_invTransitionWidth", false));
parameterIDs.push_back(program->getParameterID(evalName + "_cutoffAngle", false));
parameterIDs.push_back(program->getParameterID(evalName + "_cosCutoffAngle", false));
parameterIDs.push_back(program->getParameterID(evalName + "_cosBeamWidth", false));
parameterIDs.push_back(program->getParameterID(evalName + "_uvFactor", false));
}
void bind(GPUProgram *program, const std::vector<int> &parameterIDs, int &textureUnitOffset) const {
program->setParameter(parameterIDs[0], m_worldToEmitter);
program->setParameter(parameterIDs[1], m_invTransitionWidth);
program->setParameter(parameterIDs[2], m_cutoffAngle);
program->setParameter(parameterIDs[3], m_cosCutoffAngle);
program->setParameter(parameterIDs[4], m_cosBeamWidth);
program->setParameter(parameterIDs[5], m_uvFactor);
}
MTS_DECLARE_CLASS()
private:
Transform m_worldToEmitter;
Float m_invTransitionWidth;
Float m_cutoffAngle, m_cosCutoffAngle;
Float m_cosBeamWidth, m_uvFactor;
ref<const Texture> m_texture;
ref<Shader> m_textureShader;
};
Shader *SpotEmitter::createShader(Renderer *renderer) const {
const Transform &trafo = m_worldTransform->eval(0.0f);
return new SpotEmitterShader(renderer, trafo.inverse(),
m_invTransitionWidth, m_cutoffAngle, m_cosCutoffAngle,
m_cosBeamWidth, m_uvFactor, m_texture.get());
}
MTS_IMPLEMENT_CLASS(SpotEmitterShader, false, Shader)
MTS_IMPLEMENT_CLASS_S(SpotEmitter, false, Emitter)
MTS_EXPORT_PLUGIN(SpotEmitter, "Spot light");
MTS_NAMESPACE_END