LineArt: Custom Camera

Allows line art camera to be different from scene active camera,
useful when baking multiple shots in different angle as
well as for motion graphics effect.

Reviewed By: Antonio Vazquez (antoniov)

Differential Revision: https://developer.blender.org/D12047

4 files changed, 59 insertions, 16 deletions

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c b/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c
index a7164e5bf2c..4ce1a903269 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c
@@ -264,6 +264,12 @@ static void updateDepsgraph(GpencilModifierData *md,
   else {
     add_this_collection(ctx->scene->master_collection, ctx, mode);
   }
+  if (lmd->calculation_flags & LRT_USE_CUSTOM_CAMERA) {
+    DEG_add_object_relation(
+        ctx->node, lmd->source_camera, DEG_OB_COMP_TRANSFORM, "Line Art Modifier");
+    DEG_add_object_relation(
+        ctx->node, lmd->source_camera, DEG_OB_COMP_PARAMETERS, "Line Art Modifier");
+  }
   if (ctx->scene->camera) {
     DEG_add_object_relation(
         ctx->node, ctx->scene->camera, DEG_OB_COMP_TRANSFORM, "Line Art Modifier");
@@ -280,6 +286,7 @@ static void foreachIDLink(GpencilModifierData *md, Object *ob, IDWalkFunc walk,
   walk(userData, ob, (ID **)&lmd->source_collection, IDWALK_CB_NOP);
 
   walk(userData, ob, (ID **)&lmd->source_object, IDWALK_CB_NOP);
+  walk(userData, ob, (ID **)&lmd->source_camera, IDWALK_CB_NOP);
 }
 
 static void panel_draw(const bContext *UNUSED(C), Panel *panel)
@@ -385,7 +392,12 @@ static void options_panel_draw(const bContext *UNUSED(C), Panel *panel)
     return;
   }
 
-  uiItemR(layout, ptr, "overscan", 0, NULL, ICON_NONE);
+  uiLayout *row = uiLayoutRowWithHeading(layout, false, IFACE_("Custom Camera"));
+  uiItemR(row, ptr, "use_custom_camera", 0, "", 0);
+  uiLayout *subrow = uiLayoutRow(row, true);
+  uiLayoutSetActive(subrow, RNA_boolean_get(ptr, "use_custom_camera"));
+  uiLayoutSetPropSep(subrow, true);
+  uiItemR(subrow, ptr, "source_camera", 0, "", ICON_OBJECT_DATA);
 
   uiLayout *col = uiLayoutColumn(layout, true);
 
@@ -684,10 +696,11 @@ static void composition_panel_draw(const bContext *UNUSED(C), Panel *panel)
     uiItemL(layout, IFACE_("Object is shown in front"), ICON_ERROR);
   }
 
-  uiLayout *row = uiLayoutRow(layout, false);
-  uiLayoutSetActive(row, !show_in_front);
+  uiLayout *col = uiLayoutColumn(layout, false);
+  uiLayoutSetActive(col, !show_in_front);
 
-  uiItemR(row, ptr, "stroke_depth_offset", UI_ITEM_R_SLIDER, IFACE_("Depth Offset"), ICON_NONE);
+  uiItemR(col, ptr, "stroke_depth_offset", UI_ITEM_R_SLIDER, IFACE_("Depth Offset"), ICON_NONE);
+  uiItemR(col, ptr, "offset_towards_custom_camera", 0, IFACE_("Towards Custom Camera"), ICON_NONE);
 }
 
 static void panelRegister(ARegionType *region_type)
diff --git a/source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h b/source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h
index d170a6033fa..727de381fa4 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h
+++ b/source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h
@@ -311,6 +311,7 @@ typedef struct LineartRenderBuffer {
   bool cam_is_persp;
   float cam_obmat[4][4];
   double camera_pos[3];
+  double active_camera_pos[3]; /* Stroke offset calculation may use active or selected camera. */
   double near_clip, far_clip;
   float shift_x, shift_y;
   float crease_threshold;
@@ -595,7 +596,9 @@ void MOD_lineart_chain_connect(LineartRenderBuffer *rb);
 void MOD_lineart_chain_discard_short(LineartRenderBuffer *rb, const float threshold);
 void MOD_lineart_chain_split_angle(LineartRenderBuffer *rb, float angle_threshold_rad);
 void MOD_lineart_smooth_chains(LineartRenderBuffer *rb, float tolerance);
-void MOD_lineart_chain_offset_towards_camera(LineartRenderBuffer *rb, float dist);
+void MOD_lineart_chain_offset_towards_camera(LineartRenderBuffer *rb,
+                                             float dist,
+                                             bool use_custom_camera);
 
 int MOD_lineart_chain_count(const LineartEdgeChain *ec);
 void MOD_lineart_chain_clear_picked_flag(LineartCache *lc);
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c b/source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c
index 57eeeb96541..8b7f53b8a36 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c
+++ b/source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c
@@ -1009,7 +1009,9 @@ void MOD_lineart_chain_split_angle(LineartRenderBuffer *rb, float angle_threshol
   }
 }
 
-void MOD_lineart_chain_offset_towards_camera(LineartRenderBuffer *rb, float dist)
+void MOD_lineart_chain_offset_towards_camera(LineartRenderBuffer *rb,
+                                             float dist,
+                                             bool use_custom_camera)
 {
   float dir[3];
   float cam[3];
@@ -1017,6 +1019,14 @@ void MOD_lineart_chain_offset_towards_camera(LineartRenderBuffer *rb, float dist
   float view_clamp[3];
   copy_v3fl_v3db(cam, rb->camera_pos);
   copy_v3fl_v3db(view, rb->view_vector);
+
+  if (use_custom_camera) {
+    copy_v3fl_v3db(cam, rb->camera_pos);
+  }
+  else {
+    copy_v3fl_v3db(cam, rb->active_camera_pos);
+  }
+
   if (rb->cam_is_persp) {
     LISTBASE_FOREACH (LineartEdgeChain *, ec, &rb->chains) {
       LISTBASE_FOREACH (LineartEdgeChainItem *, eci, &ec->chain) {
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.c b/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.c
index f8dda2f9174..ea2619a9328 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.c
+++ b/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.c
@@ -2998,7 +2998,7 @@ void MOD_lineart_destroy_render_data(LineartGpencilModifierData *lmd)
   }
 }
 
-static LineartCache *lineart_init_cache()
+static LineartCache *lineart_init_cache(void)
 {
   LineartCache *lc = MEM_callocN(sizeof(LineartCache), "Lineart Cache");
   return lc;
@@ -3016,6 +3016,8 @@ void MOD_lineart_clear_cache(struct LineartCache **lc)
 
 static LineartRenderBuffer *lineart_create_render_buffer(Scene *scene,
                                                          LineartGpencilModifierData *lmd,
+                                                         Object *camera,
+                                                         Object *active_camera,
                                                          LineartCache *lc)
 {
   LineartRenderBuffer *rb = MEM_callocN(sizeof(LineartRenderBuffer), "Line Art render buffer");
@@ -3024,10 +3026,10 @@ static LineartRenderBuffer *lineart_create_render_buffer(Scene *scene,
   lmd->render_buffer_ptr = rb;
   lc->rb_edge_types = lmd->edge_types_override;
 
-  if (!scene || !scene->camera || !lc) {
+  if (!scene || !camera || !lc) {
     return NULL;
   }
-  Camera *c = scene->camera->data;
+  Camera *c = camera->data;
   double clipping_offset = 0;
 
   if (lmd->calculation_flags & LRT_ALLOW_CLIPPING_BOUNDARIES) {
@@ -3035,8 +3037,11 @@ static LineartRenderBuffer *lineart_create_render_buffer(Scene *scene,
     clipping_offset = 0.0001;
   }
 
-  copy_v3db_v3fl(rb->camera_pos, scene->camera->obmat[3]);
-  copy_m4_m4(rb->cam_obmat, scene->camera->obmat);
+  copy_v3db_v3fl(rb->camera_pos, camera->obmat[3]);
+  if (active_camera) {
+    copy_v3db_v3fl(rb->active_camera_pos, active_camera->obmat[3]);
+  }
+  copy_m4_m4(rb->cam_obmat, camera->obmat);
   rb->cam_is_persp = (c->type == CAM_PERSP);
   rb->near_clip = c->clip_start + clipping_offset;
   rb->far_clip = c->clip_end - clipping_offset;
@@ -4082,6 +4087,7 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
   LineartRenderBuffer *rb;
   Scene *scene = DEG_get_evaluated_scene(depsgraph);
   int intersections_only = 0; /* Not used right now, but preserve for future. */
+  Object *use_camera;
 
   double t_start;
 
@@ -4091,14 +4097,24 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
 
   BKE_scene_camera_switch_update(scene);
 
-  if (!scene->camera) {
-    return 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) {
+      return false;
+    }
+  }
+  else {
+    if (!scene->camera) {
+      return false;
+    }
+    use_camera = scene->camera;
   }
 
   LineartCache *lc = lineart_init_cache();
   *cached_result = lc;
 
-  rb = lineart_create_render_buffer(scene, lmd, lc);
+  rb = lineart_create_render_buffer(scene, lmd, use_camera, scene->camera, lc);
 
   /* Triangle thread testing data size varies depending on the thread count.
    * See definition of LineartTriangleThread for details. */
@@ -4118,7 +4134,7 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
   /* Get view vector before loading geometries, because we detect feature lines there. */
   lineart_main_get_view_vector(rb);
   lineart_main_load_geometries(
-      depsgraph, scene, scene->camera, rb, lmd->calculation_flags & LRT_ALLOW_DUPLI_OBJECTS);
+      depsgraph, scene, use_camera, rb, lmd->calculation_flags & LRT_ALLOW_DUPLI_OBJECTS);
 
   if (!rb->vertex_buffer_pointers.first) {
     /* No geometry loaded, return early. */
@@ -4191,7 +4207,8 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
     }
 
     if (enable_stroke_depth_offset && lmd->stroke_depth_offset > FLT_EPSILON) {
-      MOD_lineart_chain_offset_towards_camera(rb, lmd->stroke_depth_offset);
+      MOD_lineart_chain_offset_towards_camera(
+          rb, lmd->stroke_depth_offset, lmd->flags & LRT_GPENCIL_OFFSET_TOWARDS_CUSTOM_CAMERA);
     }
 
     /* Finally transfer the result list into cache. */