uniform sampler2D normal;
uniform vec2 mouse;
uniform float Za;
     vec4 effect(vec4 color,sampler2D tex,vec2 tc,vec2 pc)
     {
     vec4 img_color = texture2D( tex, tc );
     vec4 normalColor = texture2D( normal, tc );
     float X = (mouse.x - pc.x);
     float Y = (mouse.y - pc.y);
     float Z = Za;
     float dotProduct = X * normalColor.r + Y * normalColor.g + Z * normalColor.b;
     dotProduct /= sqrt(X * X + Y * Y + Z * Z) * sqrt(normalColor.r * normalColor.r + normalColor.g * normalColor.g + normalColor.b * normalColor.b);
     float factor = dotProduct;
     img_color.r = img_color.r + factor;
     img_color.g = img_color.g + factor;
     img_color.b = img_color.b + factor;
     return img_color;
     }