DRW: DebugDraw: Port module to C++ and add GPU capabilities

This is a complete rewrite of the draw debug drawing module in C++.
It uses `GPUStorageBuf` to store the data to be drawn and use indirect
drawing. This makes it easier to do a mirror API for GPU shaders.

The C++ API class is exposed through `draw_debug.hh` and should be used
when possible in new code.

However, the debug drawing will not work for platform not yet supporting
`GPUStorageBuf`. Also keep in mind that this module must only be used
in debug build for performance and compatibility reasons.

1 files changed, 15 insertions, 0 deletions

diff --git a/source/blender/draw/intern/shaders/draw_debug_draw_display_vert.glsl b/source/blender/draw/intern/shaders/draw_debug_draw_display_vert.glsl
new file mode 100644
index 00000000000..92c546aa203
--- /dev/null
+++ b/source/blender/draw/intern/shaders/draw_debug_draw_display_vert.glsl
@@ -0,0 +1,15 @@
+
+/**
+ * Display debug edge list.
+ **/
+
+void main()
+{
+  /* Skip the first vertex containing header data. */
+  DRWDebugVert vert = drw_debug_verts_buf[gl_VertexID + 1];
+  vec3 pos = uintBitsToFloat(uvec3(vert.pos0, vert.pos1, vert.pos2));
+  vec4 col = vec4((uvec4(vert.color) >> uvec4(0, 8, 16, 24)) & 0xFFu);
+
+  interp.color = col;
+  gl_Position = persmat * vec4(pos, 1.0);
+}