From 14285445283ecc8890f7e1c4b4eb92cef3f0a8ed Mon Sep 17 00:00:00 2001
From: Miguel Pozo <pragma37>
Date: Mon, 1 Feb 2021 18:24:15 +0100
Subject: Python API: option for render engines to delegate Freestyle render to
 Eevee

Eevee is now used for Freestyle rendering by default, since other engines are
unlikely to have support for this. Workbench and Cycles do their own rendering.

RenderEngine add-ons can do their own Freestyle rendering by setting
bl_use_custom_freestyle = True.

Differential Revision: https://developer.blender.org/D8335
---
 source/blender/makesrna/intern/rna_render.c |  8 ++++++++
 source/blender/render/RE_engine.h           |  1 +
 source/blender/render/intern/pipeline.c     | 25 +++++++++++++++++++++++++
 3 files changed, 34 insertions(+)

(limited to 'source')

diff --git a/source/blender/makesrna/intern/rna_render.c b/source/blender/makesrna/intern/rna_render.c
index 3126f3e11f4..0c2860c05e7 100644
--- a/source/blender/makesrna/intern/rna_render.c
+++ b/source/blender/makesrna/intern/rna_render.c
@@ -848,6 +848,14 @@ static void rna_def_render_engine(BlenderRNA *brna)
   RNA_def_property_ui_text(
       prop, "Use Eevee Viewport", "Uses Eevee for viewport shading in LookDev shading mode");
 
+  prop = RNA_def_property(srna, "bl_use_custom_freestyle", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "type->flag", RE_USE_CUSTOM_FREESTYLE);
+  RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
+  RNA_def_property_ui_text(
+      prop,
+      "Use Custom Freestyle",
+      "Handles freestyle rendering on its own, instead of delegating it to EEVEE");
+
   prop = RNA_def_property(srna, "bl_use_gpu_context", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "type->flag", RE_USE_GPU_CONTEXT);
   RNA_def_property_flag(prop, PROP_REGISTER_OPTIONAL);
diff --git a/source/blender/render/RE_engine.h b/source/blender/render/RE_engine.h
index 1af40ac760b..c31a41f66d5 100644
--- a/source/blender/render/RE_engine.h
+++ b/source/blender/render/RE_engine.h
@@ -64,6 +64,7 @@ extern "C" {
 #define RE_USE_SPHERICAL_STEREO 128
 #define RE_USE_STEREO_VIEWPORT 256
 #define RE_USE_GPU_CONTEXT 512
+#define RE_USE_CUSTOM_FREESTYLE 1024
 
 /* RenderEngine.flag */
 #define RE_ENGINE_ANIMATION 1
diff --git a/source/blender/render/intern/pipeline.c b/source/blender/render/intern/pipeline.c
index 320f8b8ed03..8567835f55c 100644
--- a/source/blender/render/intern/pipeline.c
+++ b/source/blender/render/intern/pipeline.c
@@ -2007,13 +2007,38 @@ void RE_RenderFrame(Render *re,
   G.is_rendering = false;
 }
 
+static void change_renderdata_engine(Render *re, const char *new_engine)
+{
+  if (!STREQ(re->r.engine, new_engine)) {
+    if (re->engine) {
+      RE_engine_free(re->engine);
+      re->engine = NULL;
+    }
+    BLI_strncpy(re->r.engine, new_engine, sizeof(re->r.engine));
+  }
+}
+
 #ifdef WITH_FREESTYLE
+static bool use_eevee_for_freestyle_render(Render *re)
+{
+  RenderEngineType *type = RE_engines_find(re->r.engine);
+  return !(type->flag & RE_USE_CUSTOM_FREESTYLE);
+}
+
 void RE_RenderFreestyleStrokes(Render *re, Main *bmain, Scene *scene, int render)
 {
   re->result_ok = 0;
   if (render_init_from_main(re, &scene->r, bmain, scene, NULL, NULL, 0, 0)) {
     if (render) {
+      char scene_engine[32];
+      BLI_strncpy(scene_engine, re->r.engine, sizeof(scene_engine));
+      if (use_eevee_for_freestyle_render(re)) {
+        change_renderdata_engine(re, RE_engine_id_BLENDER_EEVEE);
+      }
+
       do_render_3d(re);
+
+      change_renderdata_engine(re, scene_engine);
     }
   }
   re->result_ok = 1;
-- 
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