Lighting & Material

Example 1/5

#include ”glut.h”void display();void reshape(int, int);void lighting();int main(int argc, char** argv){

glutInit(&argc, argv);glutInitWindowSize(400, 400);glutInitWindowPosition(0, 0);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA | GLUT_DEPTH);glutCreateWindow("Planet");glutDisplayFunc(display);glutReshapeFunc(reshape);glutMainLoop();return 0;

}

Example 2/5

void lighting(){

GLfloat mat_diffuse[] = {1.0, 0.0, 0.0, 1.0};GLfloat mat_specular[] = {0.0, 0.0, 1.0, 1.0};GLfloat mat_ambient[] = {0.0, 1.0, 0.0, 1.0};GLfloat mat_shininess[] = {50.0};

GLfloat light_specular[] = {1.0, 1.0, 1.0, 1.0};GLfloat light_diffuse[] = {1.0, 1.0, 1.0, 1.0};GLfloat light_ambient[] = {0.0, 0.0, 0.0, 1.0};GLfloat light_position[] = {5.0, 5.0, 10.0, 0.0};

glClearColor(0.0, 0.0, 0.0, 0.0);glShadeModel(GL_SMOOTH);

Example 3/5

// z buffer enableglEnable(GL_DEPTH_TEST);

// enable lightingglEnable(GL_LIGHTING);// set light propertyglEnable(GL_LIGHT0);glLightfv(GL_LIGHT0, GL_POSITION, light_position);glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);

// set material propertyglMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);

}

Example 4/5

void display(){

lighting();glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glutSolidSphere(0.8, 128, 128);glFlush();

}

void reshape (int w, int h){ glViewport (0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode (GL_PROJECTION); glLoadIdentity(); glOrtho (-1.0, 1.0, -1.0, 1.0, -1.0, 1.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity();}

Example 5/5

Specular : blue Diffuse : red Ambient : green

Color Specifying shading model

void glShadeModel(GLenum mode ); GL_FLAT / GL_SMOOTH (default) http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/

glfunc03_24rw.asp

GL_FLAT

GL_SMOOTH

Hidden-Surface Removal

Apply HSR in OpenGL glutInitDisplayMode(GLUT_DEPTH);

Enable the depth buffer glEnable(GL_DEPTH_TEST);

Enable depth test glClear(GL_DEPTH_BUFFER_BIT);

When you wish to clean the depth buffer

Lighting 1/5

Enable lighting glEnable(GL_LIGHTING)

Set light property glEnable(GL_LIGHT0) ~

glEnable(GL_LIGHT7)

Lighting 2/5

void glLightfv(GLenum light, GLenum pname, GLfloat param)

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc03_88z8.asp

Pname Def. Value Meaning

GL_AMBIENT (0.0, 0.0, 0.0, 0.0) ambient RGBA intensity of lightGL_DIFFUSE (1.0, 1.0, 1.0, 1.0) diffuse RGBA intensity of lightGL_SPECULAR (1.0, 1.0, 1.0, 1.0) specular RGBA intensity of lightGL_POSITION (0.0, 0.0, 1.0, 0.0) (x, y, z, w) position of lightGL_SPOT_DIRECTION (0.0, 0.0, -1.0) (x, y, z) direction of spotlightGL_SPOT_EXPONENT 0.0 spotlight exponentGL_SPOT_CUTOFF 180.0 spotlight cutoff angleGL_CONSTANT_ATTENUATION 1.0 constant attenuation factorGL_LINEAR_ATTENUATION 0.0 linear attenuation factorGL_QUADRATIC_ATTENUATION 0.0 quadratic attenuation factor

Lighting 3/5

Attenuation d: distance between the light's position and

the vertex kc = GL_CONSTANT_ATTENUATION kl = GL_LINEAR_ATTENUATION kq = GL_QUADRATIC_ATTENUATION If light is directional light, the attenuation is

always 1

2

1

dkdkkFacrornAttenuatio

qlc

Lighting 4/5

How to create a spot light? Define your light as positional light Define light spot direction

GLfloat spot_direction[] = { -1.0, -1.0, 0.0 };glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction);

Define light spot exponentglLightf(GL_LIGHT1, GL_SPOT_EXPONENT, 2.0);

Define light spot cutoff The value for GL_SPOT_CUTOFF is restricted to being within

the range [0.0,90.0] (unless it has the special value 180.0 (default)).

Lighting 5/5

Material 1/4

Define material properties of objects. void glMaterial{if}[v](GLenum face,

GLenum pname, TYPE[*] param); face: GL_FRONT, GL_BACK, GL_FRONT_AND_BACK http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/

glfunc03_7cq4.aspPname Def. Value Meaning

GL_AMBIENT (0.2, 0.2, 0.2, 1.0) ambient color of materialGL_DIFFUSE (0.8, 0.8, 0.8, 1.0) diffuse color of materialGL_AMBIENT_AND_DIFFUSE ambient and diffuse color of

materialGL_SPECULAR (0.0, 0.0, 0.0, 1.0) specular color of materialGL_SHININESS 0.0 specular exponentGL_EMISSION (0.0, 0.0, 0.0, 1.0) emissive color of materialGL_COLOR_INDEXES (0, 1, 1) ambient, diffuse, and specular color

indices

Material 2/4

No Ambien

t

Gray Ambien

t

Blue Ambien

t

Diffuse Only

Specular

Higher Shinines

s

Emission

Normal Vector

glNormal{34}{isfd}[v](TYPE* normal); Assign normal vector for vertices the normal vector should be assigned

before you assign vertex Normal vectors must be normalize.

OpenGL can automatically normalize normal vector by glEnable( GL_NORMALIZE ) .