Kendall Gassner

For my final project I wanted to simulate a dog playing fetch with a user. My interactive graphic throws a ball using the coordinates of a mouse click. The ball is thrown towards the area which the mouse was pressed and bounces once the ball hits the ground. Once the ball is bouncing the dog begins running towards the ball.

My Completed Goals:

  1. Calculating the the proper translation of the ball using physics (gravity, acceleration and velocity).
  2. Using Blender to detach the legs of the dog mesh. Then using the individual legs to simulate a walking motion through rotations around the x axis.
  3. Moving the entire dog mesh in the direction of the thrown ball.
  4. Adding a ground and texture to the ground to create a grass like effect.
  5. Adding randomly placed clouds in the sky.
  6. Tint the background color to act as a sky


  1. I originally struggled to get the legs of the dog to rotate around the dog’s joints. After struggling a long time and looking back at lab6 where we rotated arms about shoulders I realized I was not moving the legs to the origin before rotating them. In the end I had to move each dog leg to the origin then rotate the leg in the direction I wanted it to move. Finally I had to move it back to the place its supposed to be attached to the dog at. The code looked something like this:

    if(i == 1){

     MV->translate(vec3(-0.25, 1.35, -.35));

     MV->rotate(moveLeg, vec3(1, 0, 0));

     MV->translate(vec3(0.25, -1.35, .35));


  2. I had multiple problems adding texture to my ground. First I was using a cube.obj file that did not have texture coordinates inside of it. In the end it was easiest to get a different obj file rather then creating my own texture coordinates or switching the shape.cpp file to the shape.cpp file from lab9 which automatically adds texture coordinates for you. The second issue I had when I was adding texture was scaling. I originally scaled my cube to (100, 0, 100) because I wanted the cube to be flat under the dog and ball. This made the image appear distorted because my normals were off. Changing the cube scale to (100, 1, 100) fixed the problem and still ensured the cube was under the dog and ball.

  3. Creating a function that calculates the position of the ball as it is being thrown down the z access was confusing. I originally had issues with using a float to represent gravity. I ended up creating an acceleration vector: (0, -9.8, 0) that would make the ball fall—simulating the gravity. I also had issues ensuring the ball would stop falling once it reached the “ground” height. To fix this I created a velocity vector that was the direction of the mouse click. When the balls position in the y direction reached the “ground” height I set the velocity in the y direction to 0;


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