CSCI 420 Computer Graphics OpenGL Cheat Sheet Create a Window glutInit(&argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGBA); glutInitWindowSize(500, 500); glutInitWindowPosition (0, 0); glutCreateWindow (win_name); Clear a Window glClearColor (0.0, 0.0, 0.0, 1.0); glClear(GL_COLOR_BUFFER_BIT);

Double Buffering glutInitDisplayMode (GLUT_DOUBLE | . . .); glutSwapBuffers( );

Depth Testing glutInitDisplayMode (GLUT_DEPTH | . . .); glEnable (GL_DEPTH_TEST); glClear (GL_DEPTH_BUFFER_BIT | . . .);

Establish a Viewport and a Clipping Region glViewport (0, 0, w, h); glMatrixMode (GL_PROJECTION); glLoadIdentity( ); glOrtho (-50.0, 50.0, -50.0, 50.0, -1.0, 1.0); glMatrixMode(GL_MODELVIEW);

Projections and Locating the Camera glOrtho (-50.0, 50.0, -50.0, 50.0, -1.0, 1.0); glFrustum ( left, right, bottom, top, near, far); gluPerspective(fovy, (GLfloat) w/(GLfloat) h, near, far); gluLookAt (eyex, eyey, eyez, centerx, centery, centerz, upx, upy, upz);

Callback and Related Functions glutReshapeFunc (myReshape); glutDisplayFunc (myDisplay); glutIdleFunc (spinDisplay); glutMouseFunc (mouse); glutKeyboardFunc (keyboard); glutMainLoop ( ); glutPostRedisplay ( );

Lighting and Materials glLightf (source, parameter, value); glLightfv (source, parameter, pointer to array); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glLightModelfv(GL_LIGHT_MODEL_AMBIENT, global_ambient);

Move Around glPushMatrix( ); glPopMatrix( ); glLoadIdentity ( ); glRotatef(spin, 0.0, 0.0, 1.0); glTranslatef(3.0, 2.0, 0.0); glScalef(1.0, 2.0, 1.0); Menus void color_menu(int id) { if(id == 1) {r = 1.0; g = 0.0; b = 0.0;}. . . c_menu = glutCreateMenu(color_menu); glutAddMenuEntry("Red",1); glutAttachMenu(GLUT_RIGHT_BUTTON); glutAddSubMenu("Colors", c_menu); Text glRasterPos2i(textX, textY); glutBitmapCharacter (GLUT_BITMAP_8_BY_13, ch); Functions to Draw glColor3f (red, green, blue); glBegin (GL_TRIANGLES); glVertex3f(3.0, 4.0, 0.0); glEnd(); // Alternatively glEnableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer (3, GL_FLOAT, 0, vertices); glColorPointer (3, GL_FLOAT, 0, carray); glDrawElements (GL_QUADS, 24, GL_UNSIGNED_BYTE, cubeIndex);

glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, diffuse);

Blending and Antialiasing glEnable(GL_BLEND); glBlendFunc (source_factor, destination_factor); glDepthMask (GL_FALSE); // sets the depth buffer to read // only glEnable (GL_POINT_SMOOTH); glEnable (GL_LINE_SMOOTH); glEnable (GL_SMOOTHING); Bezier Curves and Surfaces glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]); glEnable(GL_MAP1_VERTEX_3); glEvalCoord1f((GLfloat) i/30.0); glMapGrid1f (100, 0.0, 1.0); glEvalMesh1(GL_LINE, 0, 100); Textures glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexImage2D(GL_TEXTURE_2D, 0, 3, checkImageWidth, checkImageHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, &checkImage[0][0][0]); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glEnable(GL_TEXTURE_2D); glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);

3D Transformations Translatef (xt, yt, zt)

Rotatef( , 0.0, 0.0, 1.0)

Scalef(sx, sy, sz)

1

0

0

xt

cos( )

-sin( )

0

0

sx

0

0

0

0

1

0

yt

sin( )

cos( )

0

0

0

sy

0

0

0

0

1

zt

0

0

1

0

0

0

sz

0

0

0

0

1

0

0

0

1

0

0

0

1

There are similar rotation matrices about the X and Y axes.

Projection Matrices Simple Orthogonal

Simple Perspective

1

0

0

0

1

0

0

0

0

1

0

0

0

1

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

1/d

0

Orthogonal Projection to Canonical View Volume 2/(Xmax-Xmin)

0

0

-(Xmax+Xmin)/(Xmax-Xmin)

0

2/(Ymax-Ymin)

0

-(Ymax+Ymin)/(Ymax-Ymin)

0

0

2/(Zmax-Zmin)

-(Zmax+Zmin)/(Zmax-Zmin)

0

0

0

1

Perspective Normalization Matrix (assumes right projection and fovy of 90 degrees) 1

0

0

0

0

1

0

0

α = (Zmax + Zmin)/(Zmax - Zmin)

0

0

α

β

β = (2*Zmax*Zmin)/(Zmax - Zmin)

0

0

-1

0

General Perspective Projection Matrix 2*Zmin /(Xmax-Xmin)

0

(Xmax+Xmin)/(Xmax-Xmin)

0

0

2*Zmin/ (Ymax-Ymin)

(Ymax+Ymin)/(Ymax-Ymin)

0

0

0

-(Zmax+Zmin)/(Zmax-Zmin)

-2*Zmax*Zmin/(Zmax-Zmin)

0

0

-1

0