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/**
@file GLight.cpp
@maintainer Morgan McGuire, matrix@graphics3d.com
@created 2003-11-12
@edited 2007-10-22
*/
#include "G3D/GLight.h"
#include "G3D/Sphere.h"
namespace G3D {
GLight::GLight() {
position = Vector4(0, 0, 0, 0);
color = Color3::white();
spotDirection = Vector3(0, 0, -1);
spotCutoff = 180;
enabled = false;
attenuation[0] = 1.0;
attenuation[1] = 0.0;
attenuation[2] = 0.0;
specular = true;
diffuse = true;
}
GLight GLight::directional(const Vector3& toLight, const Color3& color, bool s, bool d) {
GLight L;
L.position = Vector4(toLight.direction(), 0);
L.color = color;
L.specular = s;
L.diffuse = d;
return L;
}
GLight GLight::point(const Vector3& pos, const Color3& color, float constAtt, float linAtt, float quadAtt, bool s, bool d) {
GLight L;
L.position = Vector4(pos, 1);
L.color = color;
L.attenuation[0] = constAtt;
L.attenuation[1] = linAtt;
L.attenuation[2] = quadAtt;
L.specular = s;
L.diffuse = d;
return L;
}
GLight GLight::spot(const Vector3& pos, const Vector3& pointDirection, float cutOffAngleDegrees, const Color3& color, float constAtt, float linAtt, float quadAtt, bool s, bool d) {
GLight L;
L.position = Vector4(pos, 1.0f);
L.spotDirection = pointDirection.direction();
debugAssert(cutOffAngleDegrees <= 90);
L.spotCutoff = cutOffAngleDegrees;
L.color = color;
L.attenuation[0] = constAtt;
L.attenuation[1] = linAtt;
L.attenuation[2] = quadAtt;
L.specular = s;
L.diffuse = d;
return L;
}
bool GLight::operator==(const GLight& other) const {
return (position == other.position) &&
(spotDirection == other.spotDirection) &&
(spotCutoff == other.spotCutoff) &&
(attenuation[0] == other.attenuation[0]) &&
(attenuation[1] == other.attenuation[1]) &&
(attenuation[2] == other.attenuation[2]) &&
(color == other.color) &&
(enabled == other.enabled) &&
(specular == other.specular) &&
(diffuse == other.diffuse);
}
bool GLight::operator!=(const GLight& other) const {
return !(*this == other);
}
Sphere GLight::effectSphere(float cutoff) const {
if (position.w == 0) {
// Directional light
return Sphere(Vector3::zero(), (float)inf());
} else {
// Avoid divide by zero
cutoff = max(cutoff, 0.0001f);
float maxIntensity = max(color.r, max(color.g, color.b));
float radius = (float)inf();
if (attenuation[2] != 0) {
// Solve I / attenuation.dot(1, r, r^2) < cutoff for r
//
// a[0] + a[1] r + a[2] r^2 > I/cutoff
//
float a = attenuation[2];
float b = attenuation[1];
float c = attenuation[0] - maxIntensity / cutoff;
float discrim = square(b) - 4 * a * c;
if (discrim >= 0) {
discrim = sqrt(discrim);
float r1 = (-b + discrim) / (2 * a);
float r2 = (-b - discrim) / (2 * a);
if (r1 < 0) {
if (r2 > 0) {
radius = r2;
}
} else if (r2 > 0) {
radius = min(r1, r2);
} else {
radius = r1;
}
}
} else if (attenuation[1] != 0) {
// Solve I / attenuation.dot(1, r) < cutoff for r
//
// r * a[1] + a[0] = I / cutoff
// r = (I / cutoff - a[0]) / a[1]
float radius = (maxIntensity / cutoff - attenuation[0]) / attenuation[1];
radius = max(radius, 0.0f);
}
return Sphere(position.xyz(), radius);
}
}
}
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