Computer Graphics

Suppose you want to create an animation of the blue rectangle rotating about the origin (about the Z-axis).

Here is the code for a vertex shader for this program:

attribute vec4 vPosition;

attribute vec4 vColor;

varying vec4 fColor;

uniform float theta; 

void main()

{

float anglez = radians( theta );

float c = cos( anglez );

float s = sin( anglez );

mat4 rz =

mat4(c.z,-s.z,0.0,0.0,s.z,c.z,0.0,0.0,0.0,0.0,1.0,0.0,0.0,0.0,0.0,1.0);

fColor = vColor;

gl_Position = rz * vPosition;

}

Assume that the rotation increment amount for each frame is +2 degrees and stored in a global called Anginc, and the total rotation amount is in a global called thetaz . Show the complete render() function you would write to do this. You may assume you have already gotten the uniform attribute location for theta by calling thetaLoc = gl.getUniformLocation(program, "theta");