1 files changed, 230 insertions, 0 deletions
diff --git a/source/blender/draw/intern/shaders/common_subdiv_custom_data_interp_comp.glsl b/source/blender/draw/intern/shaders/common_subdiv_custom_data_interp_comp.glsl
new file mode 100644
index 00000000000..36c3970d9a0
--- /dev/null
+++ b/source/blender/draw/intern/shaders/common_subdiv_custom_data_interp_comp.glsl
@@ -0,0 +1,230 @@
+
+/* To be compile with common_subdiv_lib.glsl */
+
+layout(std430, binding = 1) readonly restrict buffer sourceBuffer
+{
+#ifdef GPU_FETCH_U16_TO_FLOAT
+  uint src_data[];
+#else
+  float src_data[];
+#endif
+};
+
+layout(std430, binding = 2) readonly restrict buffer facePTexOffset
+{
+  uint face_ptex_offset[];
+};
+
+layout(std430, binding = 3) readonly restrict buffer patchCoords
+{
+  BlenderPatchCoord patch_coords[];
+};
+
+layout(std430, binding = 4) readonly restrict buffer extraCoarseFaceData
+{
+  uint extra_coarse_face_data[];
+};
+
+layout(std430, binding = 5) writeonly restrict buffer destBuffer
+{
+#ifdef GPU_FETCH_U16_TO_FLOAT
+  uint dst_data[];
+#else
+  float dst_data[];
+#endif
+};
+
+struct Vertex {
+  float vertex_data[DIMENSIONS];
+};
+
+void clear(inout Vertex v)
+{
+  for (int i = 0; i < DIMENSIONS; i++) {
+    v.vertex_data[i] = 0.0;
+  }
+}
+
+Vertex read_vertex(uint index)
+{
+  Vertex result;
+#ifdef GPU_FETCH_U16_TO_FLOAT
+  uint base_index = index * 2;
+  if (DIMENSIONS == 4) {
+    uint xy = src_data[base_index];
+    uint zw = src_data[base_index + 1];
+
+    float x = float((xy >> 16) & 0xffff) / 65535.0;
+    float y = float(xy & 0xffff) / 65535.0;
+    float z = float((zw >> 16) & 0xffff) / 65535.0;
+    float w = float(zw & 0xffff) / 65535.0;
+
+    result.vertex_data[0] = x;
+    result.vertex_data[1] = y;
+    result.vertex_data[2] = z;
+    result.vertex_data[3] = w;
+  }
+  else {
+    /* This case is unsupported for now. */
+    clear(result);
+  }
+#else
+  uint base_index = index * DIMENSIONS;
+  for (int i = 0; i < DIMENSIONS; i++) {
+    result.vertex_data[i] = src_data[base_index + i];
+  }
+#endif
+  return result;
+}
+
+void write_vertex(uint index, Vertex v)
+{
+#ifdef GPU_FETCH_U16_TO_FLOAT
+  uint base_index = dst_offset + index * 2;
+  if (DIMENSIONS == 4) {
+    uint x = uint(v.vertex_data[0] * 65535.0);
+    uint y = uint(v.vertex_data[1] * 65535.0);
+    uint z = uint(v.vertex_data[2] * 65535.0);
+    uint w = uint(v.vertex_data[3] * 65535.0);
+
+    uint xy = x << 16 | y;
+    uint zw = z << 16 | w;
+
+    dst_data[base_index] = xy;
+    dst_data[base_index + 1] = zw;
+  }
+  else {
+    /* This case is unsupported for now. */
+    dst_data[base_index] = 0;
+  }
+#else
+  uint base_index = dst_offset + index * DIMENSIONS;
+  for (int i = 0; i < DIMENSIONS; i++) {
+    dst_data[base_index + i] = v.vertex_data[i];
+  }
+#endif
+}
+
+Vertex interp_vertex(Vertex v0, Vertex v1, Vertex v2, Vertex v3, vec2 uv)
+{
+  Vertex result;
+  for (int i = 0; i < DIMENSIONS; i++) {
+    float e = mix(v0.vertex_data[i], v1.vertex_data[i], uv.x);
+    float f = mix(v2.vertex_data[i], v3.vertex_data[i], uv.x);
+    result.vertex_data[i] = mix(e, f, uv.y);
+  }
+  return result;
+}
+
+void add_with_weight(inout Vertex v0, Vertex v1, float weight)
+{
+  for (int i = 0; i < DIMENSIONS; i++) {
+    v0.vertex_data[i] += v1.vertex_data[i] * weight;
+  }
+}
+
+Vertex average(Vertex v0, Vertex v1)
+{
+  Vertex result;
+  for (int i = 0; i < DIMENSIONS; i++) {
+    result.vertex_data[i] = (v0.vertex_data[i] + v1.vertex_data[i]) * 0.5;
+  }
+  return result;
+}
+
+uint get_vertex_count(uint coarse_polygon)
+{
+  uint number_of_patches = face_ptex_offset[coarse_polygon + 1] - face_ptex_offset[coarse_polygon];
+  if (number_of_patches == 1) {
+    /* If there is only one patch for the current coarse polygon, then it is a quad. */
+    return 4;
+  }
+  /* Otherwise, the number of patches is the number of vertices. */
+  return number_of_patches;
+}
+
+uint get_polygon_corner_index(uint coarse_polygon, uint patch_index)
+{
+  uint patch_offset = face_ptex_offset[coarse_polygon];
+  return patch_index - patch_offset;
+}
+
+uint get_loop_start(uint coarse_polygon)
+{
+  return extra_coarse_face_data[coarse_polygon] & coarse_face_loopstart_mask;
+}
+
+void main()
+{
+  /* We execute for each quad. */
+  uint quad_index = get_global_invocation_index();
+  if (quad_index >= total_dispatch_size) {
+    return;
+  }
+
+  uint start_loop_index = quad_index * 4;
+
+  /* Find which coarse polygon we came from. */
+  uint coarse_polygon = coarse_polygon_index_from_subdiv_quad_index(quad_index, coarse_poly_count);
+  uint loop_start = get_loop_start(coarse_polygon);
+
+  /* Find the number of vertices for the coarse polygon. */
+  Vertex v0, v1, v2, v3;
+  clear(v0);
+  clear(v1);
+  clear(v2);
+  clear(v3);
+
+  uint number_of_vertices = get_vertex_count(coarse_polygon);
+  if (number_of_vertices == 4) {
+    /* Interpolate the src data. */
+    v0 = read_vertex(loop_start + 0);
+    v1 = read_vertex(loop_start + 1);
+    v2 = read_vertex(loop_start + 2);
+    v3 = read_vertex(loop_start + 3);
+  }
+  else {
+    /* Interpolate the src data for the center. */
+    uint loop_end = loop_start + number_of_vertices - 1;
+    Vertex center_value;
+    clear(center_value);
+
+    float weight = 1.0 / float(number_of_vertices);
+
+    for (uint l = loop_start; l < loop_end; l++) {
+      add_with_weight(center_value, read_vertex(l), weight);
+    }
+
+    /* Interpolate between the previous and next corner for the middle values for the edges. */
+    uint patch_index = uint(patch_coords[start_loop_index].patch_index);
+    uint current_coarse_corner = get_polygon_corner_index(coarse_polygon, patch_index);
+    uint next_coarse_corner = (current_coarse_corner + 1) % number_of_vertices;
+    uint prev_coarse_corner = (current_coarse_corner + number_of_vertices - 1) %
+                              number_of_vertices;
+
+    v0 = read_vertex(loop_start);
+    v1 = average(v0, read_vertex(loop_start + next_coarse_corner));
+    v3 = average(v0, read_vertex(loop_start + prev_coarse_corner));
+
+    /* Interpolate between the current value, and the ones for the center and mid-edges. */
+    v2 = center_value;
+  }
+
+  /* Do a linear interpolation of the data based on the UVs for each loop of this subdivided quad.
+   */
+  for (uint loop_index = start_loop_index; loop_index < start_loop_index + 4; loop_index++) {
+    BlenderPatchCoord co = patch_coords[loop_index];
+    vec2 uv = decode_uv(co.encoded_uv);
+    /* NOTE: v2 and v3 are reversed to stay consistent with the interpolation weight on the x-axis:
+     *
+     * v3 +-----+ v2
+     *    |     |
+     *    |     |
+     * v0 +-----+ v1
+     *
+     * otherwise, weight would be `1.0 - uv.x` for `v2 <-> v3`, but `uv.x` for `v0 <-> v1`.
+     */
+    Vertex result = interp_vertex(v0, v1, v3, v2, uv);
+    write_vertex(loop_index, result);
+  }
+}