uniform float PREFIX(output_coord_to_slice_num); uniform float PREFIX(slice_num_to_input_coord); uniform float PREFIX(slice_offset_to_input_coord); uniform float PREFIX(offset); vec4 FUNCNAME(vec2 tc) { // DIRECTION_VERTICAL will be #defined to 1 if we are expanding vertically, // and 0 otherwise. #if DIRECTION_VERTICAL float sliced_coord = 1.0 - tc.y; #else float sliced_coord = tc.x; #endif // Find out which slice we are in, and a 0..1 coordinate for the offset within that slice. float slice_num = floor(sliced_coord * PREFIX(output_coord_to_slice_num)); float slice_offset = fract(sliced_coord * PREFIX(output_coord_to_slice_num)); // Find out where this slice begins in the input data, and then offset from that. float input_coord = slice_num * PREFIX(slice_num_to_input_coord) + slice_offset * PREFIX(slice_offset_to_input_coord) + PREFIX(offset); #if DIRECTION_VERTICAL return INPUT(vec2(tc.x, 1.0 - input_coord)); #else return INPUT(vec2(input_coord, tc.y)); #endif } #undef DIRECTION_VERTICAL