The drawLight() function is a light debugging tool.
drawLight() takes as an argument the GL index of the lamp : GL_LIGHT0, GL_LIGHT1... and displays a symbolic representation of the light. This function is usefull for debugging your light setup.
#include <QGLViewer/qglviewer.h>
class Viewer : public QGLViewer {
protected:
virtual void draw();
virtual void init();
virtual QString helpString() const;
private:
qglviewer::ManipulatedFrame *light1;
qglviewer::ManipulatedFrame *light2;
};
#include "drawLight.h"
#include <math.h>
#include <QGLViewer/manipulatedFrame.h>
using namespace std;
using namespace qglviewer;
void Viewer::draw() {
float pos[4] = {1.0, 0.5, 1.0, 0.0};
// Directionnal light
glLightfv(GL_LIGHT0, GL_POSITION, pos);
pos[3] = 1.0;
// Spot light
Vec pos1 = light1->position();
pos[0] = float(pos1.x);
pos[1] = float(pos1.y);
pos[2] = float(pos1.z);
glLightfv(GL_LIGHT1, GL_POSITION, pos);
glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION,
light1->inverseTransformOf(Vec(0, 0, 1)));
// Point light
Vec pos2 = light2->position();
pos[0] = float(pos2.x);
pos[1] = float(pos2.y);
pos[2] = float(pos2.z);
glLightfv(GL_LIGHT2, GL_POSITION, pos);
// Draws the spiral
const float nbSteps = 200.0;
glBegin(GL_QUAD_STRIP);
for (float i = 0; i < nbSteps; ++i) {
float ratio = i / nbSteps;
float angle = 21.0 * ratio;
float c = cos(angle);
float s = sin(angle);
float r1 = 1.0 - 0.8 * ratio;
float r2 = 0.8 - 0.8 * ratio;
float alt = ratio - 0.5;
const float nor = .5;
const float up = sqrt(1.0 - nor * nor);
glColor3f(1 - ratio, 0.2f, ratio);
glNormal3f(nor * c, up, nor * s);
glVertex3f(r1 * c, alt, r1 * s);
glVertex3f(r2 * c, alt + 0.05, r2 * s);
}
glEnd();
drawLight(GL_LIGHT0);
if (light1->grabsMouse())
drawLight(GL_LIGHT1, 1.2f);
else
drawLight(GL_LIGHT1);
if (light2->grabsMouse())
drawLight(GL_LIGHT2, 1.2f);
else
drawLight(GL_LIGHT2);
}
void Viewer::init() {
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Light0 is the default ambient light
glEnable(GL_LIGHT0);
// Light1 is a spot light
glEnable(GL_LIGHT1);
const GLfloat light_ambient[4] = {0.8f, 0.2f, 0.2f, 1.0};
const GLfloat light_diffuse[4] = {1.0, 0.4f, 0.4f, 1.0};
const GLfloat light_specular[4] = {1.0, 0.0, 0.0, 1.0};
glLightf(GL_LIGHT1, GL_SPOT_EXPONENT, 3.0);
glLightf(GL_LIGHT1, GL_SPOT_CUTOFF, 20.0);
glLightf(GL_LIGHT1, GL_CONSTANT_ATTENUATION, 0.5);
glLightf(GL_LIGHT1, GL_LINEAR_ATTENUATION, 1.0);
glLightf(GL_LIGHT1, GL_QUADRATIC_ATTENUATION, 1.5);
glLightfv(GL_LIGHT1, GL_AMBIENT, light_ambient);
glLightfv(GL_LIGHT1, GL_SPECULAR, light_specular);
glLightfv(GL_LIGHT1, GL_DIFFUSE, light_diffuse);
// Light2 is a classical directionnal light
glEnable(GL_LIGHT2);
const GLfloat light_ambient2[4] = {0.2f, 0.2f, 2.0, 1.0};
const GLfloat light_diffuse2[4] = {0.8f, 0.8f, 1.0, 1.0};
const GLfloat light_specular2[4] = {0.0, 0.0, 1.0, 1.0};
glLightfv(GL_LIGHT2, GL_AMBIENT, light_ambient2);
glLightfv(GL_LIGHT2, GL_SPECULAR, light_specular2);
glLightfv(GL_LIGHT2, GL_DIFFUSE, light_diffuse2);
light1 = new ManipulatedFrame();
light2 = new ManipulatedFrame();
setMouseTracking(true);
light1->setPosition(0.5, 0.5, 0);
// Align z axis with -position direction : look at scene center
light1->setOrientation(Quaternion(Vec(0, 0, 1), -light1->position()));
light2->setPosition(-0.5, 0.5, 0);
restoreStateFromFile();
help();
}
QString Viewer::helpString() const {
QString text("<h2>D r a w L i g h t</h2>");
text += "The <i>drawLight()</i> function displays a representation of the "
"OpenGL lights ";
text += "of your scene. This is convenient for debugging your light "
"setup.<br><br>";
text += "This scene features a directionnal ligth (arrow), a spot light "
"(cone) and a point ";
text += "light source (sphere). The representation color, position and shape "
"matches the light setup.<br><br>";
text += "Hover over the point light or the spot light to manipulate it using "
"the mouse (right ";
text += "button translates and left button rotates).";
return text;
}
#include "drawLight.h"
#include <qapplication.h>
int main(int argc, char **argv) {
QApplication application(argc, argv);
Viewer viewer;
viewer.setWindowTitle("drawLight");
viewer.show();
return application.exec();
}
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