2 // uniform float PREFIX(output_coord_to_slice_num);
3 // uniform float PREFIX(slice_num_to_input_coord);
4 // uniform float PREFIX(slice_offset_to_input_coord);
5 // uniform float PREFIX(normalized_offset);
7 vec4 FUNCNAME(vec2 tc) {
8 // DIRECTION_VERTICAL will be #defined to 1 if we are expanding vertically,
10 #if DIRECTION_VERTICAL
11 float sliced_coord = 1.0 - tc.y;
13 float sliced_coord = tc.x;
16 // Find out which slice we are in, and a 0..1 coordinate for the offset within that slice.
17 float slice_num = floor(sliced_coord * PREFIX(output_coord_to_slice_num));
18 float slice_offset = fract(sliced_coord * PREFIX(output_coord_to_slice_num));
20 // Find out where this slice begins in the input data, and then offset from that.
21 float input_coord = slice_num * PREFIX(slice_num_to_input_coord) + slice_offset * PREFIX(slice_offset_to_input_coord) + PREFIX(normalized_offset);
23 #if DIRECTION_VERTICAL
24 return INPUT(vec2(tc.x, 1.0 - input_coord));
26 return INPUT(vec2(input_coord, tc.y));
30 #undef DIRECTION_VERTICAL