CSE 167 HW3 Extra Credit Demo

For the extra credit portion, I created a simple 3D modeling system using Bezier and B-Spline curves. Due to limited time was given, the only modeling option implemented is surface of resolution. Users will be able to draw Bezier or B-Spline curve the same way HW3 does and visualize the surface of revolution created by rotating the curve around the y-axis on the second screen.

How I create the surface of revolution

I use an array to store points that are used to draw the curve, which are in [0, 1], and transform them to 3D points by adding the z value as 0. Then I create rotation matrices to rotate these points around the y-axis. The number of rotations and degrees to rotate in each rotation is determined by a variable called levelOfDetails. The number of rotations equals to levelOfDetails and the degrees equals to 360.0 / levelOfDetails. To draw these new vertices as a surface, I need to connect them to form a mesh (or wireframe). I won’t go too deep but this is how it look:

            curve_i curve_i+1            
        
            v1------v3
            
            |     /  |
            
            |   /    |
            
            v2------v4

Calcuate the normals of these triangles is trivial.

Commands to use in the second screen

• enter - draw the surface of revolution based on the curve in the first window
• “w” - toggle wireframe mode
• ”+” - increase the level of details
• ”-” - decrease the level of details
• “r” - reset the position
• left arrow- rotate left
• right arrow- rotate right
• up arrow - rotate up
• down arrow - rotate left

Screenshots

Video (click the image below)