texturity.js/src/shaders/precompiled/normal.js

WebGL based library for drawing textures

export default {
    vertex: `
        attribute vec2 position;
        varying mediump vec2 texcoord;
        void main(void) {
            texcoord = (position+1.0)/2.0;
            gl_Position = vec4(position, 0.0, 1.0);
        }`,
    fragment:`
        uniform lowp vec2 resolution;
        varying mediump vec2 texcoord;
        uniform sampler2D texture;
        uniform mediump float scale;

        lowp float grey(lowp vec3 color){
            return dot(color.rgb, vec3(0.299, 0.587, 0.114));
        }

        void main(void) {
            lowp float PIXEL_WIDTH = 1.0/resolution.x;
            lowp float PIXEL_HEIGHT = 1.0/resolution.y;
            lowp float c = grey(texture2D(texture, texcoord).rgb);
            lowp float cx = grey(texture2D(texture, texcoord+vec2(PIXEL_WIDTH, 0.0)).rgb);
            lowp float cy = grey(texture2D(texture, texcoord+vec2(0.0, PIXEL_HEIGHT)).rgb);


            lowp float dx = (c - cx) * scale;
            lowp float dy = (c - cy) * scale;
            lowp float nz = 1.0;
            lowp float len = sqrt(dx * dx + dy * dy + nz * nz);

            lowp float nx = dx / len;
            lowp float ny = -dy / len;
            nz = nz / len;

            lowp vec3 r = (vec3(nx, ny, nz)+1.0)/2.0;


            gl_FragColor = vec4(r,1.0);

        }`
}