EEVEE: Render Passes

This patch adds new render passes to EEVEE. These passes include:

* Emission
* Diffuse Light
* Diffuse Color
* Glossy Light
* Glossy Color
* Environment
* Volume Scattering
* Volume Transmission
* Bloom
* Shadow

With these passes it will be possible to use EEVEE effectively for
compositing. During development we kept a close eye on how to get similar
results compared to cycles render passes there are some differences that
are related to how EEVEE works. For EEVEE we combined the passes to
`Diffuse` and `Specular`. There are no transmittance or sss passes anymore.
Cycles will be changed accordingly.

Cycles volume transmittance is added to multiple surface col passes. For
EEVEE we left the volume transmittance as a separate pass.

Known Limitations

* All materials that use alpha blending will not be rendered in the render
  passes. Other transparency modes are supported.
* More GPU memory is required to store the render passes. When rendering
  a HD image with all render passes enabled at max extra 570MB GPU memory is
  required.

Implementation Details

An overview of render passes have been described in
https://wiki.blender.org/wiki/Source/Render/EEVEE/RenderPasses

Future Developments

* In this implementation the materials are re-rendered for Diffuse/Glossy
  and Emission passes. We could use multi target rendering to improve the
  render speed.
* Other passes can be added later
* Don't render material based passes when only requesting AO or Shadow.
* Add more passes to the system. These could include Cryptomatte, AOV's, Vector,
  ObjectID, MaterialID, UV.

Reviewed By: Clément Foucault

Differential Revision: https://developer.blender.org/D6331

1 files changed, 46 insertions, 64 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_subsurface.c b/source/blender/draw/engines/eevee/eevee_subsurface.c
index e94fc903694..98e799acb5e 100644
--- a/source/blender/draw/engines/eevee/eevee_subsurface.c
+++ b/source/blender/draw/engines/eevee/eevee_subsurface.c
@@ -33,7 +33,7 @@
 #include "GPU_extensions.h"
 
 static struct {
-  struct GPUShader *sss_sh[4];
+  struct GPUShader *sss_sh[3];
 } e_data = {{NULL}}; /* Engine data */
 
 extern char datatoc_common_view_lib_glsl[];
@@ -64,8 +64,7 @@ static void eevee_create_shader_subsurface(void)
 
   e_data.sss_sh[0] = DRW_shader_create_fullscreen(frag_str, "#define FIRST_PASS\n");
   e_data.sss_sh[1] = DRW_shader_create_fullscreen(frag_str, "#define SECOND_PASS\n");
-  e_data.sss_sh[2] = DRW_shader_create_fullscreen(frag_str, "#define RESULT_ACCUM\n");
-  e_data.sss_sh[3] = DRW_shader_create_fullscreen(frag_translucent_str,
+  e_data.sss_sh[2] = DRW_shader_create_fullscreen(frag_translucent_str,
                                                   "#define EEVEE_TRANSLUCENCY\n" SHADER_DEFINES);
 
   MEM_freeN(frag_translucent_str);
@@ -85,9 +84,10 @@ void EEVEE_subsurface_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
   common_data->sss_jitter_threshold = scene_eval->eevee.sss_jitter_threshold;
 }
 
-void EEVEE_subsurface_draw_init(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data *vedata)
+void EEVEE_subsurface_draw_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 {
   EEVEE_EffectsInfo *effects = vedata->stl->effects;
+  EEVEE_StorageList *stl = vedata->stl;
   EEVEE_FramebufferList *fbl = vedata->fbl;
   EEVEE_TextureList *txl = vedata->txl;
   DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
@@ -138,72 +138,64 @@ void EEVEE_subsurface_draw_init(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data
                                   {GPU_ATTACHMENT_NONE,
                                    GPU_ATTACHMENT_TEXTURE(effects->sss_irradiance),
                                    GPU_ATTACHMENT_TEXTURE(effects->sss_radius)});
+    if ((stl->g_data->render_passes & EEVEE_RENDER_PASS_DIFFUSE_LIGHT) != 0) {
+      EEVEE_subsurface_output_init(sldata, vedata, 0);
+    }
+    else {
+      GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_accum_fb);
+      txl->sss_accum = NULL;
+    }
   }
   else {
     /* Cleanup to release memory */
     GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_blur_fb);
     GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_resolve_fb);
     GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_clear_fb);
+    GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_accum_fb);
     effects->sss_stencil = NULL;
     effects->sss_blur = NULL;
     effects->sss_irradiance = NULL;
     effects->sss_radius = NULL;
+    txl->sss_accum = NULL;
   }
 }
 
-static void set_shgrp_stencil(void *UNUSED(userData), DRWShadingGroup *shgrp)
-{
-  DRW_shgroup_stencil_mask(shgrp, 255);
-}
-
 void EEVEE_subsurface_output_init(EEVEE_ViewLayerData *UNUSED(sldata),
                                   EEVEE_Data *vedata,
-                                  uint tot_samples)
+                                  uint UNUSED(tot_samples))
 {
   EEVEE_FramebufferList *fbl = vedata->fbl;
   EEVEE_TextureList *txl = vedata->txl;
   EEVEE_StorageList *stl = vedata->stl;
   EEVEE_EffectsInfo *effects = stl->effects;
 
-  if (effects->enabled_effects & EFFECT_SSS) {
-    const eGPUTextureFormat texture_format_light = (tot_samples > 128) ? GPU_RGBA32F : GPU_RGBA16F;
-    const eGPUTextureFormat texture_format_color = (tot_samples > 512) ? GPU_RGBA32F : GPU_RGBA16F;
-    DRW_texture_ensure_fullscreen_2d(&txl->sss_dir_accum, texture_format_light, 0);
-    DRW_texture_ensure_fullscreen_2d(&txl->sss_col_accum, texture_format_color, 0);
-
-    GPUTexture *stencil_tex = effects->sss_stencil;
+  const eGPUTextureFormat texture_format_light = GPU_RGBA32F;
+  const bool texture_created = txl->sss_accum == NULL;
+  DRW_texture_ensure_fullscreen_2d(&txl->sss_accum, texture_format_light, 0);
 
-    if (GPU_depth_blitting_workaround()) {
-      DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
-      /* Blitting stencil buffer does not work on macOS + Radeon Pro.
-       * Blit depth instead and use sss_stencil's depth as depth texture,
-       * and dtxl->depth as stencil mask. */
-      stencil_tex = dtxl->depth;
-    }
+  GPUTexture *stencil_tex = effects->sss_stencil;
 
-    GPU_framebuffer_ensure_config(&fbl->sss_accum_fb,
-                                  {GPU_ATTACHMENT_TEXTURE(stencil_tex),
-                                   GPU_ATTACHMENT_TEXTURE(txl->sss_dir_accum),
-                                   GPU_ATTACHMENT_TEXTURE(txl->sss_col_accum)});
+  if (GPU_depth_blitting_workaround()) {
+    DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+    /* Blitting stencil buffer does not work on macOS + Radeon Pro.
+     * Blit depth instead and use sss_stencil's depth as depth texture,
+     * and dtxl->depth as stencil mask. */
+    stencil_tex = dtxl->depth;
+  }
 
-    /* Clear texture. */
-    if (DRW_state_is_image_render() || effects->taa_current_sample == 1) {
-      float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
-      GPU_framebuffer_bind(fbl->sss_accum_fb);
-      GPU_framebuffer_clear_color(fbl->sss_accum_fb, clear);
-    }
+  GPU_framebuffer_ensure_config(
+      &fbl->sss_accum_fb,
+      {GPU_ATTACHMENT_TEXTURE(stencil_tex), GPU_ATTACHMENT_TEXTURE(txl->sss_accum)});
 
-    /* Make the opaque refraction pass mask the sss. */
-    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_CLIP_PLANES |
-                     DRW_STATE_WRITE_STENCIL | DRW_STATE_STENCIL_ALWAYS;
-    DRW_pass_state_set(vedata->psl->refract_pass, state);
-    DRW_pass_foreach_shgroup(vedata->psl->refract_pass, &set_shgrp_stencil, NULL);
-  }
-  else {
-    /* Cleanup to release memory */
-    DRW_TEXTURE_FREE_SAFE(txl->sss_dir_accum);
-    DRW_TEXTURE_FREE_SAFE(txl->sss_col_accum);
-    GPU_FRAMEBUFFER_FREE_SAFE(fbl->sss_accum_fb);
+  /* Clear texture.
+   * Due to the late initialization of the SSS it can happen that the `taa_current_sample` is
+   * already higher than one. This is noticeable when loading a file that has the diffuse light
+   * pass in look dev mode active. `texture_created` will make sure that newly created textures
+   * are cleared. */
+  if (DRW_state_is_image_render() || effects->taa_current_sample == 1 || texture_created) {
+    float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+    GPU_framebuffer_bind(fbl->sss_accum_fb);
+    GPU_framebuffer_clear_color(fbl->sss_accum_fb, clear);
   }
 }
 
@@ -222,7 +214,6 @@ void EEVEE_subsurface_cache_init(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data
   DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_STENCIL_EQUAL;
   DRW_PASS_CREATE(psl->sss_blur_ps, state);
   DRW_PASS_CREATE(psl->sss_resolve_ps, state | DRW_STATE_BLEND_ADD);
-  DRW_PASS_CREATE(psl->sss_accum_ps, state | DRW_STATE_BLEND_ADD);
   DRW_PASS_CREATE(psl->sss_translucency_ps, state | DRW_STATE_BLEND_ADD);
 }
 
@@ -245,6 +236,8 @@ void EEVEE_subsurface_add_pass(EEVEE_ViewLayerData *sldata,
   DRW_shgroup_uniform_texture_ref(grp, "sssRadius", &effects->sss_radius);
   DRW_shgroup_uniform_block(grp, "sssProfile", sss_profile);
   DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
+  DRW_shgroup_uniform_block(
+      grp, "renderpass_block", EEVEE_material_default_render_pass_ubo_get(sldata));
   DRW_shgroup_stencil_mask(grp, sss_id);
   DRW_shgroup_call(grp, quad, NULL);
 
@@ -256,22 +249,10 @@ void EEVEE_subsurface_add_pass(EEVEE_ViewLayerData *sldata,
   DRW_shgroup_uniform_texture_ref(grp, "sssRadius", &effects->sss_radius);
   DRW_shgroup_uniform_block(grp, "sssProfile", sss_profile);
   DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
+  DRW_shgroup_uniform_block(
+      grp, "renderpass_block", EEVEE_material_default_render_pass_ubo_get(sldata));
   DRW_shgroup_stencil_mask(grp, sss_id);
   DRW_shgroup_call(grp, quad, NULL);
-
-  if ((stl->g_data->render_passes & (SCE_PASS_SUBSURFACE_COLOR | SCE_PASS_SUBSURFACE_DIRECT)) !=
-      0) {
-    grp = DRW_shgroup_create(e_data.sss_sh[2], psl->sss_accum_ps);
-    DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
-    DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", depth_src);
-    DRW_shgroup_uniform_texture_ref(grp, "sssIrradiance", &effects->sss_blur);
-    DRW_shgroup_uniform_texture_ref(grp, "sssAlbedo", &effects->sss_albedo);
-    DRW_shgroup_uniform_texture_ref(grp, "sssRadius", &effects->sss_radius);
-    DRW_shgroup_uniform_block(grp, "sssProfile", sss_profile);
-    DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
-    DRW_shgroup_stencil_mask(grp, sss_id);
-    DRW_shgroup_call(grp, quad, NULL);
-  }
 }
 
 void EEVEE_subsurface_translucency_add_pass(EEVEE_ViewLayerData *sldata,
@@ -287,7 +268,7 @@ void EEVEE_subsurface_translucency_add_pass(EEVEE_ViewLayerData *sldata,
   struct GPUBatch *quad = DRW_cache_fullscreen_quad_get();
   GPUTexture **depth_src = GPU_depth_blitting_workaround() ? &effects->sss_stencil : &dtxl->depth;
 
-  DRWShadingGroup *grp = DRW_shgroup_create(e_data.sss_sh[3], psl->sss_translucency_ps);
+  DRWShadingGroup *grp = DRW_shgroup_create(e_data.sss_sh[2], psl->sss_translucency_ps);
   DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
   DRW_shgroup_uniform_texture(grp, "sssTexProfile", sss_tex_profile);
   DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", depth_src);
@@ -298,6 +279,8 @@ void EEVEE_subsurface_translucency_add_pass(EEVEE_ViewLayerData *sldata,
   DRW_shgroup_uniform_block(grp, "light_block", sldata->light_ubo);
   DRW_shgroup_uniform_block(grp, "shadow_block", sldata->shadow_ubo);
   DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
+  DRW_shgroup_uniform_block(
+      grp, "renderpass_block", EEVEE_material_default_render_pass_ubo_get(sldata));
   DRW_shgroup_stencil_mask(grp, sss_id);
   DRW_shgroup_call(grp, quad, NULL);
 }
@@ -408,11 +391,11 @@ void EEVEE_subsurface_output_accumulate(EEVEE_ViewLayerData *UNUSED(sldata), EEV
 
   if (((effects->enabled_effects & EFFECT_SSS) != 0) && (fbl->sss_accum_fb != NULL)) {
     /* Copy stencil channel, could be avoided (see EEVEE_subsurface_init) */
-    GPU_framebuffer_blit(fbl->main_fb, 0, fbl->sss_blur_fb, 0, GPU_STENCIL_BIT);
+    GPU_framebuffer_blit(fbl->main_fb, 0, fbl->sss_accum_fb, 0, GPU_STENCIL_BIT);
 
     /* Only do vertical pass + Resolve */
     GPU_framebuffer_bind(fbl->sss_accum_fb);
-    DRW_draw_pass(psl->sss_accum_ps);
+    DRW_draw_pass(psl->sss_resolve_ps);
 
     /* Restore */
     GPU_framebuffer_bind(fbl->main_fb);
@@ -424,5 +407,4 @@ void EEVEE_subsurface_free(void)
   DRW_SHADER_FREE_SAFE(e_data.sss_sh[0]);
   DRW_SHADER_FREE_SAFE(e_data.sss_sh[1]);
   DRW_SHADER_FREE_SAFE(e_data.sss_sh[2]);
-  DRW_SHADER_FREE_SAFE(e_data.sss_sh[3]);
 }