scripts/startup/bl_ui/properties_material.py

@@ -256,7 +256,12 @@ class EEVEE_NEXT_MATERIAL_PT_settings(MaterialButtonsPanel, Panel):
 
         mat = context.material
 
-        layout.prop(mat, "use_backface_culling")
+        col = layout.column(heading="Cull Backfaces")
+        col.prop(mat, "use_backface_culling", text="Camera")
+        col.prop(mat, "use_backface_culling_probe", text="Probe Capture")
+
+        layout.separator()
+
         layout.prop(mat, "blend_method")
         layout.prop(mat, "shadow_method")
 
@@ -265,7 +270,7 @@ class EEVEE_NEXT_MATERIAL_PT_settings(MaterialButtonsPanel, Panel):
         row.prop(mat, "alpha_threshold")
 
         if mat.blend_method not in {'OPAQUE', 'CLIP', 'HASHED'}:
-            layout.prop(mat, "show_transparent_back")
+            col.prop(mat, "show_transparent_back", text="Transparency")
 
         layout.prop(mat, "use_screen_refraction")
         layout.prop(mat, "pass_index")

source/blender/draw/engines/eevee_next/eevee_pipeline.cc

@@ -1081,9 +1081,13 @@ void CapturePipeline::sync()
   inst_.bind_uniform_data(&surface_ps_);
 }
 
-PassMain::Sub *CapturePipeline::surface_material_add(GPUMaterial *gpumat)
+PassMain::Sub *CapturePipeline::surface_material_add(::Material *blender_mat, GPUMaterial *gpumat)
 {
-  return &surface_ps_.sub(GPU_material_get_name(gpumat));
+  PassMain::Sub &sub_pass = surface_ps_.sub(GPU_material_get_name(gpumat));
+  GPUPass *gpupass = GPU_material_get_pass(gpumat);
+  sub_pass.shader_set(GPU_pass_shader_get(gpupass));
+  sub_pass.push_constant("double_sided", !(blender_mat->blend_flag & MA_BL_CULL_BACKFACE_PROBE));
+  return &sub_pass;
 }
 
 void CapturePipeline::render(View &view)

source/blender/draw/engines/eevee_next/eevee_pipeline.hh

@@ -371,7 +371,7 @@ class CapturePipeline {
  public:
   CapturePipeline(Instance &inst) : inst_(inst){};
 
-  PassMain::Sub *surface_material_add(GPUMaterial *gpumat);
+  PassMain::Sub *surface_material_add(::Material *blender_mat, GPUMaterial *gpumat);
 
   void sync();
   void render(View &view);
@@ -567,7 +567,7 @@ class PipelineModule {
       case MAT_PIPE_SHADOW:
         return shadow.surface_material_add(gpumat);
       case MAT_PIPE_CAPTURE:
-        return capture.surface_material_add(gpumat);
+        return capture.surface_material_add(blender_mat, gpumat);
       case MAT_PIPE_PLANAR_PREPASS:
         BLI_assert_unreachable();
         return nullptr;

source/blender/draw/engines/eevee_next/eevee_shader_shared.hh

@@ -1036,6 +1036,11 @@ struct Surfel {
   packed_float3 albedo_back;
   /** Cluster this surfel is assigned to. */
   int cluster_id;
+  /** True if the light can bounce or be emitted by the surfel back face. */
+  bool1 double_sided;
+  int _pad0;
+  int _pad1;
+  int _pad2;
   /** Surface radiance: Emission + Direct Lighting. */
   SurfelRadiance radiance_direct;
   /** Surface radiance: Indirect Lighting. Double buffered to avoid race conditions. */

source/blender/draw/engines/eevee_next/shaders/eevee_lightprobe_irradiance_ray_comp.glsl

@@ -53,7 +53,7 @@ void irradiance_capture_surfel(Surfel surfel, vec3 P, inout SphericalHarmonicL1
 void validity_capture_surfel(Surfel surfel, vec3 P, inout float validity)
 {
   vec3 L = safe_normalize(surfel.position - P);
-  bool facing = dot(-L, surfel.normal) > 0.0;
+  bool facing = surfel.double_sided || dot(-L, surfel.normal) > 0.0;
   validity += float(facing);
 }
 

source/blender/draw/engines/eevee_next/shaders/eevee_surf_capture_frag.glsl

@@ -53,9 +53,10 @@ void main()
         surfel_buf[surfel_id].radiance_direct.front.rgb = g_emission;
         surfel_buf[surfel_id].radiance_direct.front.a = 0.0;
         /* TODO(fclem): 2nd surface evaluation. */
-        surfel_buf[surfel_id].albedo_back = albedo;
-        surfel_buf[surfel_id].radiance_direct.back.rgb = g_emission;
+        surfel_buf[surfel_id].albedo_back = double_sided ? albedo : vec3(0);
+        surfel_buf[surfel_id].radiance_direct.back.rgb = double_sided ? g_emission : vec3(0);
         surfel_buf[surfel_id].radiance_direct.back.a = 0.0;
+        surfel_buf[surfel_id].double_sided = double_sided;
 
         if (!capture_info_buf.capture_emission) {
           surfel_buf[surfel_id].radiance_direct.front.rgb = vec3(0.0);

source/blender/draw/engines/eevee_next/shaders/infos/eevee_material_info.hh

@@ -182,6 +182,7 @@ GPU_SHADER_CREATE_INFO(eevee_surf_capture)
     .define("MAT_CAPTURE")
     .storage_buf(SURFEL_BUF_SLOT, Qualifier::WRITE, "Surfel", "surfel_buf[]")
     .storage_buf(CAPTURE_BUF_SLOT, Qualifier::READ_WRITE, "CaptureInfoData", "capture_info_buf")
+    .push_constant(Type::BOOL, "double_sided")
     .fragment_source("eevee_surf_capture_frag.glsl")
     .additional_info("eevee_global_ubo", "eevee_utility_texture");
 

source/blender/makesdna/DNA_material_types.h

@@ -342,6 +342,7 @@ enum {
   MA_BL_SS_REFRACTION = (1 << 1),
   MA_BL_CULL_BACKFACE = (1 << 2),
   MA_BL_TRANSLUCENCY = (1 << 3),
+  MA_BL_CULL_BACKFACE_PROBE = (1 << 4),
 };
 
 /** #Material::blend_shadow */

source/blender/makesrna/intern/rna_material.cc

@@ -858,6 +858,12 @@ void RNA_def_material(BlenderRNA *brna)
       prop, "Backface Culling", "Use back face culling to hide the back side of faces");
   RNA_def_property_update(prop, 0, "rna_Material_draw_update");
 
+  prop = RNA_def_property(srna, "use_backface_culling_probe", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, nullptr, "blend_flag", MA_BL_CULL_BACKFACE_PROBE);
+  RNA_def_property_ui_text(
+      prop, "Probe Capture Backface Culling", "Use back faces for probe captures");
+  RNA_def_property_update(prop, 0, "rna_Material_draw_update");
+
   prop = RNA_def_property(srna, "use_screen_refraction", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, nullptr, "blend_flag", MA_BL_SS_REFRACTION);
   RNA_def_property_ui_text(