You should work individually on this assignment. To receive credit, demonstrate your completed program during lab or push your code up to Bitbucket prior to class on the due date.
In lab 1, we’ll be exploring how triangles are drawn to the screen using a process called rasterization. You will adapt the provided code to request input from the user for three points that will define a triangle along with three colors associated with each point. You must draw the triangle and output the result to an image file. When drawing the triangle, you must smoothly transition the color between each of the points. Here is an example of the required behavior:
$ ./triangle
Enter 3 points (enter a point as x,y:r,g,b):
50,50:1,0,0
600,20:0,1,0
300,400:0,0,1
You entered:
50, 50 : 1, 0, 0
600, 20 : 0, 1, 0
300, 400 : 0, 0, 1
Success
Barycentric coordinates:
- FoCG Section 2.7.1 - 2D triangles
- Wikipedia: Barycentric Coordinates On Triangles
Color representation:
- FoCG Section 3.3 RGB color
- Wikipedia: RGB Color Model - Numeric Representations
Triangle Rasterization
- FoCG Section 8.1.2 - Triangle Rasterization
Bitmap generation:
- C++ Bitmap Library - The file
bitmap_image.hppis a simple (and awesome) 1 file bitmap library.
Retrieve three points (just x,y) from the user. Color can wait until Part 3. Once you have the points, calculate their bounding box. Loop over every pixel in the bounding box and set them to white (white is full strength red, green and blue so 1,1,1).
Your output should look something like:
Compute barycentric coordinates for each pixel in the bounding box. Instead of turning every pixel in the bounding box on, we’ll use barycentric coordinates to decide whether or not the current pixel is in the triangle. If it is, set the pixel to white, otherwise move on to the next pixel.
Your output should look something like:
Modify your code that retrieves input to include color values that range from 0 - 1 for a red, green and blue component for each point. Modify your loop to use the barycentric coordinates as weights and compute a color for the current pixel.
Your output should look something like:
Everything about each pixel (whether it’s on or off, it’s color, location, etc.) is calculated independently of every other pixel. All of this information could be calculated in any order and in parallel. The ability to highly parallelize graphics computations is what makes graphics hardware so powerful.