Fix T74811: GreasePencil Stereo Rendering

When using grease pencil in a stereo rendering the grease pencil objects are
only visible in the left eye. In the viewport it renders both.

Issue is related that `DRW_render_gpencil` only renders a single view. But
`DRW_render_to_image` renders all views. This patch puts this in a loop to
render both eyes.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D7154

1 files changed, 15 insertions, 4 deletions

diff --git a/source/blender/draw/engines/gpencil/gpencil_render.c b/source/blender/draw/engines/gpencil/gpencil_render.c
index 083b04c0600..496122c0483 100644
--- a/source/blender/draw/engines/gpencil/gpencil_render.c
+++ b/source/blender/draw/engines/gpencil/gpencil_render.c
@@ -104,10 +104,21 @@ void GPENCIL_render_init(GPENCIL_Data *vedata,
 
   /* FIXME(fclem): we have a precision loss in the depth buffer because of this reupload.
    * Find where it comes from! */
-  txl->render_depth_tx = DRW_texture_create_2d(
-      size[0], size[1], GPU_DEPTH_COMPONENT24, 0, do_region ? NULL : pix_z);
-  txl->render_color_tx = DRW_texture_create_2d(
-      size[0], size[1], GPU_RGBA16F, 0, do_region ? NULL : pix_col);
+  /* In multi view render the textures can be reused. */
+  if (txl->render_depth_tx && !do_clear_z) {
+    GPU_texture_update(txl->render_depth_tx, GPU_DATA_FLOAT, pix_z);
+  }
+  else {
+    txl->render_depth_tx = DRW_texture_create_2d(
+        size[0], size[1], GPU_DEPTH_COMPONENT24, 0, do_region ? NULL : pix_z);
+  }
+  if (txl->render_color_tx && !do_clear_col) {
+    GPU_texture_update(txl->render_color_tx, GPU_DATA_FLOAT, pix_col);
+  }
+  else {
+    txl->render_color_tx = DRW_texture_create_2d(
+        size[0], size[1], GPU_RGBA16F, 0, do_region ? NULL : pix_col);
+  }
 
   GPU_framebuffer_ensure_config(&fbl->render_fb,
                                 {