+in vec3 flow_tc;
+in vec2 patch_center;
+flat in int ref_layer, search_layer;
+out vec3 out_flow;
+
+uniform sampler2DArray flow_tex, image_tex;
+uniform usampler2DArray grad_tex; // Also contains the corresponding reference image.
+uniform vec2 inv_image_size, inv_prev_level_size;
+uniform uint patch_size;
+uniform uint num_iterations;
+
+vec3 unpack_gradients(uint v)
+{
+ uint vi = v & 0xffu;
+ uint xi = (v >> 8) & 0xfffu;
+ uint yi = v >> 20;
+ vec3 r = vec3(xi * (1.0f / 4095.0f) - 0.5f, yi * (1.0f / 4095.0f) - 0.5f, vi * (1.0f / 255.0f));
+ return r;
+}
+
+// Note: The third variable is the actual pixel value.
+vec3 get_gradients(vec3 tc)
+{
+ vec3 grad = unpack_gradients(texture(grad_tex, tc).x);