#version 450 core in vec2 tc; out vec2 derivatives; uniform sampler2D tex; void main() { float x_m2 = textureOffset(tex, tc, ivec2(-2, 0)).x; float x_m1 = textureOffset(tex, tc, ivec2(-1, 0)).x; float x_p1 = textureOffset(tex, tc, ivec2( 1, 0)).x; float x_p2 = textureOffset(tex, tc, ivec2( 2, 0)).x; float y_m2 = textureOffset(tex, tc, ivec2( 0, -2)).x; float y_m1 = textureOffset(tex, tc, ivec2( 0, -1)).x; float y_p1 = textureOffset(tex, tc, ivec2( 0, 1)).x; float y_p2 = textureOffset(tex, tc, ivec2( 0, 2)).x; derivatives.x = (x_p1 - x_m1) * (2.0/3.0) + (x_m2 - x_p2) * (1.0/12.0); derivatives.y = (y_p1 - y_m1) * (2.0/3.0) + (y_m2 - y_p2) * (1.0/12.0); }