Overlay Engine: Refactor & Cleanup

This is the unification of all overlays into one overlay engine as described in T65347.

I went over all the code making it more future proof with less hacks and removing old / not relevent parts.

Goals / Acheivements:
- Remove internal shader usage (only drw shaders)
- Remove viewportSize and viewportSizeInv and put them in gloabl ubo
- Fixed some drawing issues: Missing probe option and Missing Alt+B clipping of some shader
- Remove old (legacy) shaders dependancy (not using view UBO).
- Less shader variation (less compilation time at first load and less patching needed for vulkan)
- removed some geom shaders when I could
- Remove static e_data (except shaders storage where it is OK)
- Clear the way to fix some anoying limitations (dithered transparency, background image compositing etc...)
- Wireframe drawing now uses the same batching capabilities as workbench & eevee (indirect drawing).
- Reduced complexity, removed ~3000 Lines of code in draw (also removed a lot of unused shader in GPU).
- Post AA to avoid complexity and cost of MSAA.

Remaining issues:
- ~~Armature edits, overlay toggles, (... others?) are not refreshing viewport after AA is complete~~
- FXAA is not the best for wires, maybe investigate SMAA
- Maybe do something more temporally stable for AA.
- ~~Paint overlays are not working with AA.~~
- ~~infront objects are difficult to select.~~
- ~~the infront wires sometimes goes through they solid counterpart (missing clear maybe?) (toggle overlays on-off when using infront+wireframe overlay in solid shading)~~

Note: I made some decision to change slightly the appearance of some objects to simplify their drawing. Namely the empty arrows end (which is now hollow/wire) and distance points of the cameras/spots being done by lines.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6296

1 files changed, 116 insertions, 0 deletions

diff --git a/source/blender/draw/engines/overlay/shaders/armature_shape_outline_geom.glsl b/source/blender/draw/engines/overlay/shaders/armature_shape_outline_geom.glsl
new file mode 100644
index 00000000000..bd05c7f3532
--- /dev/null
+++ b/source/blender/draw/engines/overlay/shaders/armature_shape_outline_geom.glsl
@@ -0,0 +1,116 @@
+
+layout(lines_adjacency) in;
+layout(triangle_strip, max_vertices = 6) out;
+
+in vec4 pPos[];
+in vec3 vPos[];
+in vec2 ssPos[];
+in vec2 ssNor[];
+in vec4 vColSize[];
+
+flat out vec4 finalColor;
+
+vec2 compute_dir(vec2 v0, vec2 v1)
+{
+  vec2 dir = normalize(v1 - v0);
+  dir = vec2(-dir.y, dir.x);
+  return dir;
+}
+
+void emit_edge(vec2 edge_dir, vec2 hidden_dir, vec2 thick, bool is_persp)
+{
+  float fac = dot(-hidden_dir, edge_dir);
+  edge_dir *= (fac < 0.0) ? -1.0 : 1.0;
+
+  vec2 t = thick * (is_persp ? abs(vPos[1].z) : 1.0);
+  gl_Position = pPos[1];
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_set_clip_distance(gl_in[1].gl_ClipDistance);
+#endif
+  EmitVertex();
+  gl_Position.xy += t * edge_dir;
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_set_clip_distance(gl_in[1].gl_ClipDistance);
+#endif
+  EmitVertex();
+
+  t = thick * (is_persp ? abs(vPos[2].z) : 1.0);
+  gl_Position = pPos[2];
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_set_clip_distance(gl_in[2].gl_ClipDistance);
+#endif
+  EmitVertex();
+  gl_Position.xy += t * edge_dir;
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_set_clip_distance(gl_in[2].gl_ClipDistance);
+#endif
+  EmitVertex();
+}
+
+void emit_corner(const int e, vec2 thick, bool is_persp)
+{
+  vec2 corner_dir = ssNor[e];
+  vec2 t = thick * (is_persp ? abs(vPos[e].z) : 1.0);
+
+  gl_Position = pPos[e] + vec4(t * corner_dir, 0.0, 0.0);
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_set_clip_distance(gl_in[e].gl_ClipDistance);
+#endif
+  EmitVertex();
+}
+
+void main(void)
+{
+  finalColor = vec4(vColSize[0].rgb, 1.0);
+
+  bool is_persp = (ProjectionMatrix[3][3] == 0.0);
+
+  vec3 view_vec = (is_persp) ? normalize(vPos[1]) : vec3(0.0, 0.0, -1.0);
+  vec3 v10 = vPos[0] - vPos[1];
+  vec3 v12 = vPos[2] - vPos[1];
+  vec3 v13 = vPos[3] - vPos[1];
+
+  vec3 n0 = cross(v12, v10);
+  vec3 n3 = cross(v13, v12);
+
+  float fac0 = dot(view_vec, n0);
+  float fac3 = dot(view_vec, n3);
+
+  /* If one of the face is perpendicular to the view,
+   * consider it and outline edge. */
+  if (abs(fac0) > 1e-5 && abs(fac3) > 1e-5) {
+    /* If both adjacent verts are facing the camera the same way,
+     * then it isn't an outline edge. */
+    if (sign(fac0) == sign(fac3)) {
+      return;
+    }
+  }
+
+  /* Don't outline if concave edge. */
+  if (dot(n0, v13) > 0.0001) {
+    return;
+  }
+
+  float line_thickness = 2.0 * sizePixel;
+  vec2 thick = vColSize[0].w * (line_thickness * sizeViewportInv.xy);
+  vec2 edge_dir = compute_dir(ssPos[1], ssPos[2]);
+
+  vec2 hidden_point;
+  /* Take the farthest point to compute edge direction
+   * (avoid problems with point behind near plane).
+   * If the chosen point is parallel to the edge in screen space,
+   * choose the other point anyway.
+   * This fixes some issue with cubes in orthographic views.*/
+  if (vPos[0].z < vPos[3].z) {
+    hidden_point = (abs(fac0) > 1e-5) ? ssPos[0] : ssPos[3];
+  }
+  else {
+    hidden_point = (abs(fac3) > 1e-5) ? ssPos[3] : ssPos[0];
+  }
+  vec2 hidden_dir = normalize(hidden_point - ssPos[1]);
+
+  emit_corner(1, thick, is_persp);
+  emit_edge(edge_dir, hidden_dir, thick, is_persp);
+  emit_corner(2, thick, is_persp);
+  EndPrimitive();
+}