(Shader Library) Fish Eye, Dome and Barrel Distortion GLSL Post Processing Filters



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6 – Fish Eye Lens Shader

(GLSL Shader Library) Fish Eye Post Processing Filter, Dome Distortion, barrel distortion



This cool fish eye lens demo is based on the code from this link:



GLSL Vertex shader:

#version 120
uniform mat4 gxl3d_ModelViewProjectionMatrix;
void main()
{
  gl_Position = gxl3d_ModelViewProjectionMatrix * gl_Vertex;
}



GLSL Fragment shader:

#version 120
uniform sampler2D tex0;
uniform vec2 resolution;
uniform vec2 mouse;
uniform float lensSize; // 0.4

void main(void)
{
    vec2 p = gl_FragCoord.xy / resolution.xy;
    vec2 m = mouse.xy / resolution.xy;

    vec2 d = p - m;
    float r = sqrt(dot(d, d)); // distance of pixel from mouse

    vec2 uv;
    vec3 col = vec3(0.0, 0.0, 0.0);
    if (r > lensSize+0.01) 
    {
        uv = p;
        col = texture2D(tex0, vec2(uv.x, -uv.y)).xyz;
    } 
    else if (r < lensSize-0.01) 
    {
        // Thanks to Paul Bourke for these formulas; see
        // http://paulbourke.net/miscellaneous/lenscorrection/
        // and .../lenscorrection/lens.c
        // Choose one formula to uncomment:
        // SQUAREXY:
        // uv = m + vec2(d.x * abs(d.x), d.y * abs(d.y));
        // SQUARER:
        uv = m + d * r; // a.k.a. m + normalize(d) * r * r
        // SINER:
        // uv = m + normalize(d) * sin(r * 3.14159 * 0.5);
        // ASINR:
        // uv = m + normalize(d) * asin(r) / (3.14159 * 0.5);
        col = texture2D(tex0, vec2(uv.x, -uv.y)).xyz;
    }
    gl_FragColor = vec4(col, 1.0);
}




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