Welcome to CAP4730's TA page!

Homeworks

You can download the OpenGL Utility Toolkit (GLUT)  here.

Run your program on Linux machines:

• use 
      
  
          include <GL/glut.h> 
  
  
  instead of 
  
  
          include "glut.h"
  
  
  
• compile your code using makefile.  If you are writing .cpp code, please try this makefile.

Homework#3

Hint for displaying triangle mesh:

You can convert the posted .ply file into obj format, then load it in and display as triangles.

Hint for displaying texture image:

OpenGl Texture Tutorial, Opengl FAQ, more in Chapter 9.

loadBMP sample code.

Hint for displaying coordinates on screen:

Lighthouse Tutorial.

Hint for NURBS surface and lighting:

sample code, more in Chapter 12.

Homework#2

Hint for Picking:

Chapter 13 of Red Book.

See sample code.

Hint for Animation:

In order to identify the location of the tip, you can use glGetFloatv(GL_MODELVIEW_MATRIX, yourmatrix) to get the transformation applied to it.

Homework#1

Hint for 3a:

for 3a you need to create 6 curve pieces and 6 calls of glMap1f 

(while for 3c you need only one call to gluNurbsCurve) 

You can arrange that in a for-loop over segment index k from 0 to 5 where 

{

    1. I create first four local indices 

        i0 = k-1; if k-1 < 0 i0 = last = 5 

        i1 = k; 

        i2 = k+1; if... 

        i3 = k+2; if ... 

    2. compute the four coefficients of the BB form of the segment 

        c[0][xyz] = (secret formula you should determine) 

        c[1][xyz] = (2*ctlpt[i1][xyz] + 1*ctlpt[i2][xyz])/3; 

        c[2][xyz] = (1*ctlpt[i1][xyz] + 2*ctlpt[i2][xyz])/3; 

        c[3][xyz] = (secret formula you should determine) 

    3. call glMap1f(.........,&c[0][0]) 

        glEnable 

        for (l=0; l < EVALPTS, l++) glEvalCoord... 

}

Q: When the mouse clicked, how to decide which control point being picked?

A:  
glutMouseFunc() will return the window coordinates of the point you clicked, suppose it is (x,y)

World coordinates (x',y') need to be computed.  The following is the formula:

x' = ((GLfloat)x/(GLfloat)width)*(right-left)+(GLfloat)left;

similarly for y' -- be careful that the origin of the mouse coordinates is in the upper left hand corner.

width : the width of the window. 

left, right are set in

 glOrtho(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble near, GLdouble far)