CS-511 - Alternate Assignment 1 (5%)

2D function viewer

Due by: September 9, 2008

Assignment Specifications

This assignment is intended only for students who took cs411. The purpose of this assignment is to write a 2D function surface viewer. The input to your program should be a text file containing the data points of the 2D function. It is assumed that the function is sampled over regular intervals in a rectangular region. Your program should support the following rendering modes:

• wireframe (with hidden line removal).
• non-illuminated surface where color represents height (red=high, blue=low).
• illuminated uniformly-colored surface

The function surface should be rendered by triangulating the data set while maintaining the winding of the triangles consistent. This task is fairly simple under the assumption that the function is sampled over regular intervals in a rectangular region. The wireframe plot should be obtained by drawing lines between function values when $x$ is constant, and then repeating it in the $y$ direction. Hidden lines may be removed by rendering filled polygons on top of the lines with a background color (use the commands glEnable(GL_POLYGON_OFFSET_FILL); and glPolygonOffset(1.0,1.0); to prevent the deletion of the rendered lines). The following are some more specific details:

• Input file format: The input file should be a text file. The first line of this file should contain the number of rows and columns in the rectangular grid that was used to sample the function. Each subsequent line should contain the coordinates of one point $(x,y,z)$ where $z=f(x,y)$. The points should be ordered starting from top to bottom, and left to right. That is the order of elements in the file is:
  

  $$\begin{array}{c} f(x_{\min},y_{\min}), \ldots, f(x_{\max},... ...(x_{\max},y_{\max}), \ldots, f(x_{\max},y_{\max}) \end{array}$$ (1)

  
  

• Display mode: Switching the display mode should be accomplished by pressing ``1'', ``2'', ``3'' (wireframe, unlit, lit respectively).

• Viewpoint control: The arrow keys should be used to allow the user to view the surface from different viewpoints. The ``i'' and ``o'' keys should be used to zoom in/out. In the lit mode, the light source should be moved with the camera.

• Data file: A data file of a 2D sine function will be provided.

• Color setting: The way to change the color from red to blue in the non-illuminated mode is to find the minimal and maximal values of the Z coordinate. Given $z_{\min}$ and $z_{\max}$, the color at a height of $z$ should be set to: $C(z)=\alpha*(1,0,0)+(1-\alpha)*(0,0,1)$ where $\alpha = (z-z_{\min})/(z_{\max}-z_{\min})$

Electronic Submission Instructions

Please follow the submission procedure outlined in the regular assignment 1 specification.