1. Introduction of OpenGL - 3D Graphic and Animation

2. 3D Graphic
Projections – Getting 3D to 2D

3. Two Projections Orthographic Projection Perspective Projection

4. Orthographic Projections
Command
glOrtho ( double left, double right, double bottom, double top, double near, double far);

5. Perspective Projection
Command
gluPerspective ( double angle, double aspect, double near, double far);

6. Draw a 3D Model
Object Composition
Polygon
3D Model

7. Object Composition Use Transformation glPushMatrix ( );
glPopMatrix ( );
Save the current transformation state and then restore it after some objects have been placed

8. The Matrix Stack Ex. Draw a car use transformation
The car body and four wheeles
Transformation state
Wheele 4
The Car Body
Wheele 1
Wheele 2
Wheele 3
Wheele 4

9. Hidden Surface Removal
Enable Depth Testing
glEnable (GL_DEPTH_TEST);
Hidden Surface

10. Light and Surface Normal
A Normal Vector
V3 = V1 X V2
Normal Vector P3 V2 P1 V1 P2

11. Draw Quadrics (1) Rendering Spheres, Cylinders, and Disks
1. Declare a quadrics pointer
GLUquadricObj *qobj;
2. Create a quadrics object
qobj = gluNewQuadric ( );

12. Draw Quadrics (2) Rendering Spheres, Cylinders, and Disks
3. Specify the rendering attributes for the quadrics object
gluDrawStyle (qobj, GLU_FILL);
gluQuadricOrientation (qobj, GLU_OUTSIDE);
gluQuadricNormals (qobj, GLU_SMOOTH);

13. Draw Quadrics (3) Rendering Spheres, Cylinders, and Disks
4. Draw quadrics object
gluSphere (qobj, radius, slices, stacks);
gluCylinder (qobj, baseRadius, topRadius, height, slices, stacks);
gluDisk (qobj, innerRadius, outerRadius, slices, rings);

14. Draw Quadrics (4) Rendering Spheres, Cylinders, and Disks
Slices and stacks
Cylinder
slices = 6
stacks = 6
Cylinder
slices = 30
stacks = 30

15. Draw Quadrics (5) Rendering Spheres, Cylinders, and Disks
5. When you’re completely finished with drawing, destory this object
gluDeleteQuadric ( );

16. Animation
A Rotating Square
Frame 0
Frame 1
Frame 2
Frame 3

17. Animation with OpenGL and GLUT
Motion = Redraw + Swap
Double Buffering
One is displayed while the other is being drawing. When the drawing of a frame is complete, the two buffers are swapped
glutSwapBuffers ( );

18. Animation with OpenGL and GLUT
Rotation
glRotatef( angle, 0.0, 0.0, 1.0)
- rotate about the x-axis

19. Animation with OpenGL and GLUT
Rotation - delay the rotation
#include <time.h>
void sleep(unsigned int mseconds) {
clock_t goal = mseconds + clock();
while (goal > clock()); }