1. Transformation Back-face culling View frustum culling
Assignment 2 Phase 1
Transformation
Back-face culling
View frustum culling

2. Outline Implement the transformation. Implement back-face culling.
Viewing transformation
Projection transformation
Perspective division
Viewport transformaion
Implement back-face culling.
Implement view frustum culling.

3. Input and Output Input: *.view *.obj *.mtl
Same as assignment 1
Output: Wireframe of the obj with back-face culling

4. Transformation 1/3 Viewing transformaion Tview = B T
Modelview
Matrix
Projection
Matrix
Viewport
Transformation
Perspective
Division
Vertex
Viewing transformaion
Tview = B T
Implement gluLookat() in OpenGL

5. Transformation 2/3 Projection transformation Tp = NSH
Implement gluPerspective() in OpenGL, so do not need to implement H

6. Transformation 3/3 Perspective division Viewport transformation
All X,Y,Z,W are divided by W.
Viewport transformation
Tv = T S

7. Back-face culling You can perform back-face culling in World cord.
View cord.
ZN < 0
Window cord.
Clock wise 1
Back face 3 2

8. View frustum culling
eliminate the polygon that complete outside the view frustum.
Bonus: view frustum clipping
Remove the part of polygon that outside the view frustum.

9. How to draw wireframe? Render the image using glBegin(GL_LINE_LOOP);
glVertex2i(x,y); …
glEnd();

10. What to do in reshape function?
void GL_reshape(GLsizei w, GLsizei h){
glViewport(viewport->x, viewport->y,
viewport->width, viewport->height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(viewport->x, viewport->width,
viewport->y, viewport->height);
glMatrixMode(GL_MODELVIEW); }

11. UI requirement Show an input command line.
“Please input the file name.”
If I type “box”, then read box.obj and box.view etc.