displacement

uniform sampler2D tex0;
varying vec2 tcoord;
uniform sampler2D offset;
uniform float intensity;
void main() {
    // Sample the input pixel
	vec2 uv = tcoord;
	uv.y = 1-uv.y;
	vec4 c = texture2D(offset,uv);
	uv.x += (c.r-0.5)*intensity;
	uv.y += (c.g-0.5)*intensity;
	uv.x = clamp(uv.x,0,1);
	uv.y = clamp(uv.y,0,1);
    // Save the result
	gl_FragColor =  texture2D(tex0,uv);
}