Fix T60190 Z-fighting with (Culled) Backface

Create a separate pass for backface culled objects.

6 files changed, 14 insertions, 2 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index 50062088dbe..49cc8e8b791 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -269,6 +269,7 @@ static void eevee_draw_background(void *vedata)
 		}
 		EEVEE_draw_default_passes(psl);
 		DRW_draw_pass(psl->material_pass);
+		DRW_draw_pass(psl->material_pass_cull);
 		EEVEE_subsurface_data_render(sldata, vedata);
 		DRW_stats_group_end();
 
diff --git a/source/blender/draw/engines/eevee/eevee_lightprobes.c b/source/blender/draw/engines/eevee/eevee_lightprobes.c
index c0dd9a81313..b0e0a986630 100644
--- a/source/blender/draw/engines/eevee/eevee_lightprobes.c
+++ b/source/blender/draw/engines/eevee/eevee_lightprobes.c
@@ -833,7 +833,9 @@ static void lightbake_render_scene_face(int face, EEVEE_BakeRenderData *user_dat
 	DRW_draw_pass(psl->depth_pass_cull);
 	DRW_draw_pass(psl->probe_background);
 	DRW_draw_pass(psl->material_pass);
+	DRW_draw_pass(psl->material_pass_cull);
 	DRW_draw_pass(psl->sss_pass); /* Only output standard pass */
+	DRW_draw_pass(psl->sss_pass_cull);
 	EEVEE_draw_default_passes(psl);
 }
 
@@ -911,7 +913,9 @@ static void lightbake_render_scene_reflected(int layer, EEVEE_BakeRenderData *us
 	/* Shading pass */
 	EEVEE_draw_default_passes(psl);
 	DRW_draw_pass(psl->material_pass);
+	DRW_draw_pass(psl->material_pass_cull);
 	DRW_draw_pass(psl->sss_pass); /* Only output standard pass */
+	DRW_draw_pass(psl->sss_pass_cull);
 	DRW_draw_pass(psl->refract_pass);
 
 	/* Transparent */
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index cfe493cf3e4..94f484cd4d1 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -1037,7 +1037,8 @@ void EEVEE_materials_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 
 	{
 		DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_CLIP_PLANES | DRW_STATE_WIRE;
-		psl->material_pass = DRW_pass_create("Material Shader Pass", state);
+		psl->material_pass = DRW_pass_create("Material Pass", state);
+		psl->material_pass_cull = DRW_pass_create("Material Pass Cull", state | DRW_STATE_CULL_BACK);
 	}
 
 	{
@@ -1075,6 +1076,7 @@ void EEVEE_materials_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 		        DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_CLIP_PLANES |
 		        DRW_STATE_WIRE | DRW_STATE_WRITE_STENCIL);
 		psl->sss_pass = DRW_pass_create("Subsurface Pass", state);
+		psl->sss_pass_cull = DRW_pass_create("Subsurface Pass Cull", state | DRW_STATE_CULL_BACK);
 		e_data.sss_count = 0;
 	}
 
@@ -1230,7 +1232,8 @@ static void material_opaque(
 				*shgrp = DRW_shgroup_material_create(
 				        *gpumat,
 				        (use_ssrefract) ? psl->refract_pass :
-				        (use_sss) ? psl->sss_pass : psl->material_pass);
+				        (use_sss) ? ((do_cull) ? psl->sss_pass_cull : psl->sss_pass)
+				                  : ((do_cull) ? psl->material_pass_cull : psl->material_pass));
 
 				add_standard_uniforms(*shgrp, sldata, vedata, ssr_id, &ma->refract_depth,
 				                      use_diffuse, use_glossy, use_refract, use_ssrefract, false);
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index c9ae245c550..25902bce62d 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -253,7 +253,9 @@ typedef struct EEVEE_PassList {
 	struct DRWPass *refract_depth_pass_clip_cull;
 	struct DRWPass *default_pass[VAR_MAT_MAX];
 	struct DRWPass *sss_pass;
+	struct DRWPass *sss_pass_cull;
 	struct DRWPass *material_pass;
+	struct DRWPass *material_pass_cull;
 	struct DRWPass *refract_pass;
 	struct DRWPass *transparent_pass;
 	struct DRWPass *background_pass;
diff --git a/source/blender/draw/engines/eevee/eevee_render.c b/source/blender/draw/engines/eevee/eevee_render.c
index b7b592decd0..158b008bc14 100644
--- a/source/blender/draw/engines/eevee/eevee_render.c
+++ b/source/blender/draw/engines/eevee/eevee_render.c
@@ -555,6 +555,7 @@ void EEVEE_render_draw(EEVEE_Data *vedata, RenderEngine *engine, RenderLayer *rl
 		GPU_framebuffer_bind(fbl->main_fb);
 		EEVEE_draw_default_passes(psl);
 		DRW_draw_pass(psl->material_pass);
+		DRW_draw_pass(psl->material_pass_cull);
 		EEVEE_subsurface_data_render(sldata, vedata);
 		/* Effects pre-transparency */
 		EEVEE_subsurface_compute(sldata, vedata);
diff --git a/source/blender/draw/engines/eevee/eevee_subsurface.c b/source/blender/draw/engines/eevee/eevee_subsurface.c
index 5954774b00e..8abbaa64fd2 100644
--- a/source/blender/draw/engines/eevee/eevee_subsurface.c
+++ b/source/blender/draw/engines/eevee/eevee_subsurface.c
@@ -285,6 +285,7 @@ void EEVEE_subsurface_data_render(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Dat
 
 		GPU_framebuffer_bind(fbl->main_fb);
 		DRW_draw_pass(psl->sss_pass);
+		DRW_draw_pass(psl->sss_pass_cull);
 
 		/* Restore */
 		GPU_framebuffer_ensure_config(&fbl->main_fb, {