Homework 6

• Full disclosure: Hisashi Shirokawa provided some ideas used in the assignment.

1. Modify Homework 5, Question 1 to shade the function plotted.
   • Display the viewer's current eye position for understanding your orientation relative to the light source.
   • Use a fixed light source position on a single axis.
   • Use GL_FLAT to see individual polygons reflection.
   • Use different material properties for FRONT and BACK to highlight the shading (not done in example at right).
   • Define appropriate materials, see text for an example. Note that the text has an error, use:

     typedef struct {
         GLfloat ambient[4];
         GLfloat diffuse[4];
         GLfloat specular[4];
         GLfloat shininess;
     } materialStruct;

   Hints

   • Verify that the normals are correctly calculated for the surface by placing the light position on each axis (e.g. (10,0,0) should light only the right side(s) of the surface when viewing from the z-axis toward the negative z).
   • We are not creating shadows where one object blocks the light to another another.
   • Figure at right has light source at (10, -10, 0) and is viewed looking in the positive z direction. The intersecting plane is dark as the light source is below and does not cast a shadow on the surface.
   • The C function sprintf  can be used to convert formatted numbers as a string to a buffer. Disable lighting when writing. A function to write stroked text is below, a size of 0.0005 produced the results at right:

     void writeText3fStroke(GLfloat x, GLfloat y, char text[], GLfloat size) {
         glPushMatrix();
         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         glLoadIdentity();
         glOrtho(-1,1,-1,1,-1,1);
         glMatrixMode(GL_MODELVIEW);
         glLoadIdentity();
         glTranslatef(x,y,0);
         glScalef(size,size,size);
     
         for (unsigned int i=0; i<strlen(text); i++)
             glutStrokeCharacter(GLUT_STROKE_ROMAN, (int)text[i]);
     
         glMatrixMode(GL_PROJECTION);
         glPopMatrix();
         glMatrixMode(GL_MODELVIEW);
         glPopMatrix();
     }

     

2. Combine Question 1 with Homework 5 to allow the small cube to move through the shaded function. Use a fixed light.
3. Add texture of your choice to the plotted function. Cover the entire surface using a single texture, the simplest is to have OpenGL generate the texture coordinates from a linear function as described in the class notes. Be sure that specular highlights are still visible after texturing.

EMAIL

1. To  notifying that assignment is complete with subject: YOUR NAME: B481 and Homework 6.
2. Place in the OnCourse drop-box a zip file with name HW6.zip containing three directories:
   1. Directory named ONE for Question 1:
   • capture of plot of your favorite 3D function,
   • all code files (include executable) for Question 1.
   2. Directory named TWO for Question 2 with code and executable.
   3. Directory named THREE for Question 3 with code and executable.
   4. Instructions on executing.