1 files changed, 84 insertions, 0 deletions
diff --git a/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl b/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl
new file mode 100644
index 00000000000..3e640540777
--- /dev/null
+++ b/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl
@@ -0,0 +1,84 @@
+
+/**
+ * Convert DrawPrototype into draw commands.
+ */
+
+#pragma BLENDER_REQUIRE(common_math_lib.glsl)
+
+#define atomicAddAndGet(dst, val) (atomicAdd(dst, val) + val)
+
+/* This is only called by the last thread executed over the group's prototype draws. */
+void write_draw_call(DrawGroup group, uint group_id)
+{
+  DrawCommand cmd;
+  cmd.vertex_len = group.vertex_len;
+  cmd.vertex_first = group.vertex_first;
+  if (group.base_index != -1) {
+    cmd.base_index = group.base_index;
+    cmd.instance_first_indexed = group.start;
+  }
+  else {
+    cmd._instance_first_array = group.start;
+  }
+  /* Back-facing command. */
+  cmd.instance_len = group_buf[group_id].back_facing_counter;
+  command_buf[group_id * 2 + 0] = cmd;
+  /* Front-facing command. */
+  cmd.instance_len = group_buf[group_id].front_facing_counter;
+  command_buf[group_id * 2 + 1] = cmd;
+
+  /* Reset the counters for a next command gen dispatch. Avoids resending the whole data just
+   * for this purpose. Only the last thread will execute this so it is thread-safe. */
+  group_buf[group_id].front_facing_counter = 0u;
+  group_buf[group_id].back_facing_counter = 0u;
+  group_buf[group_id].total_counter = 0u;
+}
+
+void main()
+{
+  uint proto_id = gl_GlobalInvocationID.x;
+  if (proto_id >= prototype_len) {
+    return;
+  }
+
+  DrawPrototype proto = prototype_buf[proto_id];
+  uint group_id = proto.group_id;
+  bool is_inverted = (proto.resource_handle & 0x80000000u) != 0;
+  uint resource_index = (proto.resource_handle & 0x7FFFFFFFu);
+
+  /* Visibility test result. */
+  bool is_visible = ((visibility_buf[resource_index / 32u] & (1u << (resource_index % 32u)))) != 0;
+
+  DrawGroup group = group_buf[group_id];
+
+  if (!is_visible) {
+    /* Skip the draw but still count towards the completion. */
+    if (atomicAddAndGet(group_buf[group_id].total_counter, proto.instance_len) == group.len) {
+      write_draw_call(group, group_id);
+    }
+    return;
+  }
+
+  uint back_facing_len = group.len - group.front_facing_len;
+  uint front_facing_len = group.front_facing_len;
+  uint dst_index = group.start;
+  if (is_inverted) {
+    uint offset = atomicAdd(group_buf[group_id].back_facing_counter, proto.instance_len);
+    dst_index += offset;
+    if (atomicAddAndGet(group_buf[group_id].total_counter, proto.instance_len) == group.len) {
+      write_draw_call(group, group_id);
+    }
+  }
+  else {
+    uint offset = atomicAdd(group_buf[group_id].front_facing_counter, proto.instance_len);
+    dst_index += back_facing_len + offset;
+    if (atomicAddAndGet(group_buf[group_id].total_counter, proto.instance_len) == group.len) {
+      write_draw_call(group, group_id);
+    }
+  }
+
+  for (uint i = dst_index; i < dst_index + proto.instance_len; i++) {
+    /* Fill resource_id buffer for each instance of this draw */
+    resource_id_buf[i] = resource_index;
+  }
+}