Computer Graphics
Homework 09
6 hours
 
Copyright © 2000 David C. Banks

1. 2.00 hours
   Texturing in OpenGL

   Run "insight" on the SGI. Select the OpenGL Programmer's Manual and skim over chapter 2 (state management and drawing geometric objects) and chapter 9 (texture mapping). Copy the sample programs in chapter 9. Compile. Run. Take snapshots and put them on your Web page. Don't bother to tar/gzip the sample programs.

2. 3.00 hours
   Using your own texture.

   You will use your own texture file and apply it to a sphere.

   Use one of your first assignments that produced a ppm file. Read the file into an array for OpenGL to use. Create a sphere from triangles (be careful about the degenerate quadrilaterals at the north and south poles), preferably from the code you wrote for the previous assignment. Make the texture filename be a command line parameter. To create your (s,t) texture coordinates with s and t each in the interval [0,1], let s=phi/pi, and let t=theta/(2pi).

   Note that OpenGL wants the texture to have dimensions that are powers of 2, such as a 128x64 image.

   Tar and gzip your code, documentation, and Makefile. Include a description of how to run your program, giving a sample invocation (with command line flags) that works. Put images on your Web page.

3. 1.00 hours
   Animating textured spheres.

   Create (or find) a sequence of images, then texture-map them onto some spheres. Your program should expect a sequence of images to have names like texture.000.ppm texture.001.ppm .. or hurricane.000.ppm hurricane.001.ppm .. and so forth. Tar and gzip your code, documentation, and Makefile. Include a description of how to run your program, giving a sample invocation (with command line flags) that actually works. Make the spheres orbit around a point and revolve as they go. Put images/animations on your Web page.

4. Extra Credit (200 points)
   Texturing and animating the inner planets.

   Read the OpenGL Programmer's Manual, chapter 3 (Viewing), especially the section at the end on Manipulating the Matrix Stacks. The idea is to rotate/translate/rotate and draw a body such as a planet. The vertices of the planet will be transformed like this:

     p = M*p
   

   where M is the current transformation matrix. The moon's vertices will be transformed by

     p = M * R*T*R*p
   

   where R*T*R is the rotate/translate/rotate for the moon. When you glPushMatrix(), you make a copy of matrix M to use temporarily for the moon. After drawing the moon, you glPopMatrix() to clear out the residual matrix-junk that moved the moon around, leaving the matrix M back on top of the matrix stack. Then you push the matrix down the stack in order to transform the next moon. And the next, looping over all the moons.

   Since the planets are satellites of the sun, and moons are satellites of the planets, you should make a recursive call in your code. Create a C++ class that stores the number of satellites a body has, pointers to the satellite objects, and member variables with the body's rotation rate, radius, distance from its parent, and orbit rate. You will use the orbit rates for the rotations, and the distance for a translation. A method like body.update(float timeStep) will update the position of a body using the current time step, and then will call the body.satellite[i].update(timeStep) method for each of the body.numSatellites satellites belonging to the body.

   Apply textures to spheres for the inner planets and their moons, then put them in orbit. Here is some data for the size, orbit, and rotation of these planets. 1 AU = 149,597,870 km.

            average         body's  orbit's  body's
            distance        radius  year     rotation
    Body    (AU)            (km)    (days)   (days)
    ------- -----------     ------ -------  ---------
   
    Sun      0.0            695990     0.0     30   
   
    Mercury  0.38709893       2439    87.97    58.6
    Venus    0.72333199       6052   224.7   -243
    Earth    1.00000011       6378   365.26     0.997
    Mars     1.52366231       3389   687        1.02
   
   

   Here is some data for the moons.

                   average      orbit  moon
    planet.moon    distance     period radius
                   (1000km)     (days) (km)
    -----------    ---------   ------- ------
   
    Earth.Moon       384.40     27.322   1737
   
    Mars.Phobos        9.38      0.319     11
    Mars.Deimos       23.46      1.262      6
   
   

   Put images/animations on your Web page. Link to your code and documentation (but not to your copy of the textures).

5. Extra Credit (200 points)
   Animating the complete solar system, moons and all.

   Model the entire solar system. Here are some links for data. Search the Web for more. Overview. NASA. Planets. Satellites. Texture maps. More textures.

   Put images/animations on your Web page. Link your code/documentation (but not your textures -- the README will describe where to fetch them and how to convert them for your program to use).

6. Extra Credit (100 points)
   Open Inventor version

   Model the entire solar system, but use Open Inventor rather than OpenGL. Use the SoWriteAction to generate a .iv file. Convert it to VRML. Put it on your Web page.