From 954ae19b2b89dfa535dde5b201d86d3eb7a888b4 Mon Sep 17 00:00:00 2001
From: ChengduLittleA <xp8110@outlook.com>
Date: Tue, 19 Sep 2023 15:27:47 +0200
Subject: [PATCH] Fix #100596: Use sequencer override camera for line art in
 render

Line art doesn't take sequencer scene override camera into account when
computing line results, now it will try to get override camera info from
render and use that camera if line art override camera itself isn't set.

This will however not fix VSE preview line art result, since the preview
render doesn't give actual camera object, but rather uses a set of clip
planes and matrix info, thus it's probably not possible to do preview
camera override under current architecture.

Pull Request: https://projects.blender.org/blender/blender/pulls/110287
---
 .../gpencil_modifiers_legacy/CMakeLists.txt   |  1 +
 .../intern/lineart/lineart_cpu.cc             | 31 +++++++++++++------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/source/blender/gpencil_modifiers_legacy/CMakeLists.txt b/source/blender/gpencil_modifiers_legacy/CMakeLists.txt
index 567c0fe5e09..d99b30e5a66 100644
--- a/source/blender/gpencil_modifiers_legacy/CMakeLists.txt
+++ b/source/blender/gpencil_modifiers_legacy/CMakeLists.txt
@@ -13,6 +13,7 @@ set(INC
   ../editors/include
   ../makesrna
   ../render
+  ../render/intern
   ../windowmanager
   ../../../intern/eigen
 
diff --git a/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
index c87399abbad..d3293b38729 100644
--- a/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
+++ b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
@@ -52,6 +52,9 @@
 #include "DNA_scene_types.h"
 #include "MEM_guardedalloc.h"
 
+#include "RE_pipeline.h"
+#include "render_types.h"
+
 #include "lineart_intern.h"
 
 struct LineartIsecSingle {
@@ -4991,34 +4994,42 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
   LineartData *ld;
   Scene *scene = DEG_get_evaluated_scene(depsgraph);
   int intersections_only = 0; /* Not used right now, but preserve for future. */
-  Object *use_camera;
+  Object *lineart_camera = nullptr;
 
   double t_start;
   if (G.debug_value == 4000) {
     t_start = PIL_check_seconds_timer();
   }
 
+  bool use_render_camera_override = false;
   if (lmd->calculation_flags & LRT_USE_CUSTOM_CAMERA) {
     if (!lmd->source_camera ||
-        (use_camera = DEG_get_evaluated_object(depsgraph, lmd->source_camera))->type != OB_CAMERA)
+        (lineart_camera = DEG_get_evaluated_object(depsgraph, lmd->source_camera))->type !=
+            OB_CAMERA)
     {
       return false;
     }
   }
   else {
-
-    BKE_scene_camera_switch_update(scene);
-
-    if (!scene->camera) {
-      return false;
+    Render *render = RE_GetSceneRender(scene);
+    if (render && render->camera_override) {
+      lineart_camera = DEG_get_evaluated_object(depsgraph, render->camera_override);
+      use_render_camera_override = true;
+    }
+    if (!lineart_camera) {
+      BKE_scene_camera_switch_update(scene);
+      if (!scene->camera) {
+        return false;
+      }
+      lineart_camera = scene->camera;
     }
-    use_camera = scene->camera;
   }
 
   LineartCache *lc = lineart_init_cache();
   *cached_result = lc;
 
-  ld = lineart_create_render_buffer(scene, lmd, use_camera, scene->camera, lc);
+  ld = lineart_create_render_buffer(
+      scene, lmd, lineart_camera, use_render_camera_override ? lineart_camera : scene->camera, lc);
 
   /* Triangle thread testing data size varies depending on the thread count.
    * See definition of LineartTriangleThread for details. */
@@ -5042,7 +5053,7 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
 
   lineart_main_load_geometries(depsgraph,
                                scene,
-                               use_camera,
+                               lineart_camera,
                                ld,
                                lmd->calculation_flags & LRT_ALLOW_DUPLI_OBJECTS,
                                false,