I'm trying to make a barrel distortion shader for my current game project (in Game Maker), and I can't seem to figure out what's causing those giant pixels.

Vertex:
``` // // Simple passthrough vertex shader // attribute vec3 inPosition; // (x,y,z) //attribute vec3 inNormal; // (x,y,z) unused in this shader. attribute vec4 inColour; // (r,g,b,a) attribute vec2 inTextureCoord; // (u,v)

varying vec2 vvTexcoord; varying vec4 vvColour; varying vec2 v_vPosition;

uniform float BarrelPower; uniform vec4 u_uSource;

void main() { vec4 objectspacepos = vec4( inPosition.x, inPosition.y, inPosition.z, 1.0); glPosition = gmMatrices[MATRIXWORLDVIEWPROJECTION] * objectspacepos;

v_vColour = in_Colour;
v_vTexcoord = in_TextureCoord;
v_vPosition = in_Position.xy;

} Fragment: // // Simple passthrough fragment shader // varying vec2 vvTexcoord; varying vec4 vvColour; uniform vec4 uuSource; varying vec2 vvPosition; uniform float BarrelPower;

float rand(vec2 co){ return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453); }

vec2 Distort(vec2 p) { float theta = atan(p.y, p.x); float radius = length(p); radius = pow(radius, BarrelPower); p.x = radius * cos(theta); p.y = radius * sin(theta); return 0.5 * (p + 1.0); }

void main() {

//float xx = v_vTexcoord.x;
//float yy = v_vTexcoord.y;

float xx = v_vPosition.x;
float yy = v_vPosition.y;

vec2 point = vec2(xx - u_uSource.x, (yy - u_uSource.y));
float len = length(point);

float ran = 24.0*rand(vec2(u_uSource.w+xx,yy));

if(len+ran>u_uSource.z) gl_FragColor.rgb = vec3(0.,0.,0.);
else {

    vec2 cord = 2.0 * v_vTexcoord.xy - 1.0;
    vec2 uv;
    float d = length(cord);
    if ( d < 1.5 ){
        uv = Distort(cord);
    } else {
        uv = v_vTexcoord.xy;
    }

    vec4 c = texture2D( gm_BaseTexture, uv);

    gl_FragColor = v_vColour * c;

}

} ```