sobel.glsl

sobel.glsl

float intensity(in vec4 c) {
        return sqrt((c.x*c.x)+(c.y*c.y)+(c.z*c.z));
    }
    float sobel(float step, vec2 res, vec2 center, sampler2D tex) {
        float stepX = step/res.x*uDpr;
        float stepY = step/res.y*uDpr;
        float tLeft = intensity(texture(tex, center+vec2(-stepX, stepY)));
        float left = intensity(texture(tex, center+vec2(-stepX, 0)));
        float bLeft = intensity(texture(tex, center+vec2(-stepX, -stepY)));
        float top = intensity(texture(tex, center+vec2(0, stepY)));
        float bottom = intensity(texture(tex, center+vec2(0, -stepY)));
        float tRight = intensity(texture(tex, center+vec2(stepX, stepY)));
        float right = intensity(texture(tex, center+vec2(stepX, 0)));
        float bRight = intensity(texture(tex, center+vec2(stepX, -stepY)));
        float x = tLeft+2.0*left+bLeft-tRight-2.0*right-bRight;
        float y = -tLeft-2.0*top-tRight+bLeft+2.0*bottom+bRight;
        return sqrt((x*x)+(y*y));
    }