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, 30 insertions, 0 deletions

diff --git a/source/blender/draw/intern/shaders/common_colormanagement_lib.glsl b/source/blender/draw/intern/shaders/common_colormanagement_lib.glsl
new file mode 100644
index 00000000000..45f711296f3
--- /dev/null
+++ b/source/blender/draw/intern/shaders/common_colormanagement_lib.glsl
@@ -0,0 +1,30 @@
+float linearrgb_to_srgb(float c)
+{
+  if (c < 0.0031308) {
+    return (c < 0.0) ? 0.0 : c * 12.92;
+  }
+  else {
+    return 1.055 * pow(c, 1.0 / 2.4) - 0.055;
+  }
+}
+
+vec4 texture_read_as_linearrgb(sampler2D tex, bool premultiplied, vec2 co)
+{
+  /* By convention image textures return scene linear colors, but
+   * overlays still assume srgb. */
+  vec4 color = texture(tex, co);
+  /* Unpremultiply if stored multiplied, since straight alpha is expected by shaders. */
+  if (premultiplied && !(color.a == 0.0 || color.a == 1.0)) {
+    color.rgb = color.rgb / color.a;
+  }
+  return color;
+}
+
+vec4 texture_read_as_srgb(sampler2D tex, bool premultiplied, vec2 co)
+{
+  vec4 color = texture_read_as_linearrgb(tex, premultiplied, co);
+  color.r = linearrgb_to_srgb(color.r);
+  color.g = linearrgb_to_srgb(color.g);
+  color.b = linearrgb_to_srgb(color.b);
+  return color;
+}