DrawManager: Image engine support huge images.

Adding better support for drawing huge images in the image/uv editor. Also solved tearing artifacts.
The approach is that for each image/uv editor a screen space gpu texture is created that only contains
the visible pixels. When zooming or panning the gpu texture is rebuild.

Although the solution isn't memory intensive other parts of blender memory usage scales together with
the image size.

* Due to complexity we didn't implement partial updates when drawing images tiled (wrap repeat).
  This could be added, but is complicated as a change in the source could mean many different
  changes on the GPU texture. The work around for now is to tag all gpu textures to be dirty when
  changes are detected.

Original plan was to have 4 screen space images to support panning without gpu texture creation.
For now we don't see the need to implement it as the solution is already fast. Especially when
GPU memory is shared with CPU ram.

Reviewed By: fclem

Maniphest Tasks: T92525, T92903

Differential Revision: https://developer.blender.org/D13424

2 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_matrix.h b/source/blender/blenlib/BLI_math_matrix.h
index 65d654bc930..03b6ff25a4f 100644
--- a/source/blender/blenlib/BLI_math_matrix.h
+++ b/source/blender/blenlib/BLI_math_matrix.h
@@ -404,6 +404,7 @@ void invert_m4_m4_safe_ortho(float Ainv[4][4], const float A[4][4]);
 
 void scale_m3_fl(float R[3][3], float scale);
 void scale_m4_fl(float R[4][4], float scale);
+void scale_m4_v2(float R[4][4], const float scale[2]);
 
 /**
  * This computes the overall volume scale factor of a transformation matrix.
diff --git a/source/blender/blenlib/intern/math_matrix.c b/source/blender/blenlib/intern/math_matrix.c
index eaf76696a0a..f307672361b 100644
--- a/source/blender/blenlib/intern/math_matrix.c
+++ b/source/blender/blenlib/intern/math_matrix.c
@@ -2296,6 +2296,17 @@ void scale_m4_fl(float R[4][4], float scale)
   R[3][0] = R[3][1] = R[3][2] = 0.0;
 }
 
+void scale_m4_v2(float R[4][4], const float scale[2])
+{
+  R[0][0] = scale[0];
+  R[1][1] = scale[1];
+  R[2][2] = R[3][3] = 1.0;
+  R[0][1] = R[0][2] = R[0][3] = 0.0;
+  R[1][0] = R[1][2] = R[1][3] = 0.0;
+  R[2][0] = R[2][1] = R[2][3] = 0.0;
+  R[3][0] = R[3][1] = R[3][2] = 0.0;
+}
+
 void translate_m4(float mat[4][4], float Tx, float Ty, float Tz)
 {
   mat[3][0] += (Tx * mat[0][0] + Ty * mat[1][0] + Tz * mat[2][0]);