RetinotopyCallaway.frag.txt

/* RetinotopyCallaway.frag.txt */

const float twopi = 2.0*3.141592653589793;

/* Values passed from vertex shader: */
varying float Black;
varying float White;
varying vec4 Grey;
varying float Center;
varying float vertOhorz;
varying float Width;
varying float checkSize;
varying float checkPhase;
varying float screenDist;
varying float CenterX;
varying float CenterY;

void main()
{
    /* Query current output texel position: */
    vec2 pos = gl_TexCoord[0].xy;
    float currentPos; 
    float color1;

    /* Convert distance, apply shift offset: */
    float x = pos[0]-CenterX;
    float y = pos[1]-CenterY;

    float theta = twopi/4-acos(y/sqrt(screenDist*screenDist+x*x+y*y));
    float phi = atan(x/screenDist);

    if (checkPhase == 0.0) {
        color1 = White;
         }
    else {
        color1 = Black;
    }
            
    if (vertOhorz < 1.5) {
        currentPos = phi-Center;
        }
    else {
        currentPos = theta-Center;
        }
    
    float kernel = exp(-(currentPos*currentPos)/(Width*Width/2.0));
    float color = abs(color1-mod(floor(theta/checkSize)+floor(phi/checkSize),2.0));
    gl_FragColor = vec4(color,color,color,kernel);


}