DRW: Split ViewProjectionMatrix in order to increase precision

This also removes the need to compute the persmat and saves some memory
from the `ViewInfos` struct. This is needed to allow multiview support.

Initial testing found no major performance regression during vertex
heavy workload.

Test file: {F13610017}

Results:
| Platform | Master | Split Matrix|
| Linux + Mesa + AMD W6600 | 48 fps | 47 fps |
| Macbook Pro M1 | 50 fps | 51 fps |
| Linux + NVidia 1080Ti | 51 fps | 52 fps |
| Linux + Radeon Vega 64 | 25.6 fps | 26.7 fps |

Increased precision when far from origin:
{F13610024}

{F13610025}

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D16125

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/draw/engines/overlay/shaders/overlay_grid_vert.glsl b/source/blender/draw/engines/overlay/shaders/overlay_grid_vert.glsl
index b43b1eb4a52..6a027f94f49 100644
--- a/source/blender/draw/engines/overlay/shaders/overlay_grid_vert.glsl
+++ b/source/blender/draw/engines/overlay/shaders/overlay_grid_vert.glsl
@@ -39,5 +39,5 @@ void main()
     local_pos.z = clamp(local_pos.z, -1.0, 0.0);
   }
 
-  gl_Position = drw_view.persmat * vec4(real_pos, 1.0);
+  gl_Position = drw_view.winmat * (drw_view.viewmat * vec4(real_pos, 1.0));
 }