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, 89 insertions, 0 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_shadows.c b/source/blender/draw/engines/eevee/eevee_shadows.c
index 1776f535237..f5b98d464dd 100644
--- a/source/blender/draw/engines/eevee/eevee_shadows.c
+++ b/source/blender/draw/engines/eevee/eevee_shadows.c
@@ -21,6 +21,7 @@
  */
 
 #include "BLI_sys_types.h" /* bool */
+#include "BLI_string_utils.h"
 
 // #include "BLI_dynstr.h"
 // #include "BLI_rand.h"
@@ -35,11 +36,17 @@
 
 static struct {
   struct GPUShader *shadow_sh;
+  struct GPUShader *shadow_accum_sh;
 } e_data = {NULL}; /* Engine data */
 
 extern char datatoc_shadow_vert_glsl[];
 extern char datatoc_shadow_frag_glsl[];
+extern char datatoc_shadow_accum_frag_glsl[];
 extern char datatoc_common_view_lib_glsl[];
+extern char datatoc_common_uniforms_lib_glsl[];
+extern char datatoc_bsdf_common_lib_glsl[];
+extern char datatoc_lights_lib_glsl[];
+extern char datatoc_raytrace_lib_glsl[];
 
 void eevee_contact_shadow_setup(const Light *la, EEVEE_Shadow *evsh)
 {
@@ -65,6 +72,18 @@ void EEVEE_shadows_init(EEVEE_ViewLayerData *sldata)
                                                   NULL);
   }
 
+  if (!e_data.shadow_accum_sh) {
+    char *frag_str = BLI_string_joinN(datatoc_common_view_lib_glsl,
+                                      datatoc_common_uniforms_lib_glsl,
+                                      datatoc_bsdf_common_lib_glsl,
+                                      datatoc_raytrace_lib_glsl,
+                                      datatoc_lights_lib_glsl,
+                                      datatoc_shadow_accum_frag_glsl);
+
+    e_data.shadow_accum_sh = DRW_shader_create_fullscreen(frag_str, SHADER_DEFINES);
+    MEM_freeN(frag_str);
+  }
+
   if (!sldata->lights) {
     sldata->lights = MEM_callocN(sizeof(EEVEE_LightsInfo), "EEVEE_LightsInfo");
     sldata->light_ubo = DRW_uniformbuffer_create(sizeof(EEVEE_Light) * MAX_LIGHT, NULL);
@@ -170,6 +189,8 @@ void EEVEE_shadows_caster_material_add(EEVEE_ViewLayerData *sldata,
   DRW_shgroup_uniform_block(grp, "planar_block", sldata->planar_ubo);
   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, "renderpass_block", EEVEE_material_default_render_pass_ubo_get(sldata));
   DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
 
   if (alpha_threshold != NULL) {
@@ -406,7 +427,75 @@ void EEVEE_shadows_draw(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata, DRWView
   }
 }
 
+/* -------------------------------------------------------------------- */
+
+/** \name Render Passes
+ * \{ */
+
+void EEVEE_shadow_output_init(EEVEE_ViewLayerData *sldata,
+                              EEVEE_Data *vedata,
+                              uint UNUSED(tot_samples))
+{
+  EEVEE_FramebufferList *fbl = vedata->fbl;
+  EEVEE_TextureList *txl = vedata->txl;
+  EEVEE_PassList *psl = vedata->psl;
+  EEVEE_StorageList *stl = vedata->stl;
+  EEVEE_EffectsInfo *effects = stl->effects;
+  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+
+  float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+
+  /* Create FrameBuffer. */
+  const eGPUTextureFormat texture_format = GPU_R32F;
+  DRW_texture_ensure_fullscreen_2d(&txl->shadow_accum, texture_format, 0);
+
+  GPU_framebuffer_ensure_config(&fbl->shadow_accum_fb,
+                                {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(txl->shadow_accum)});
+
+  /* Clear texture. */
+  if (DRW_state_is_image_render() || effects->taa_current_sample == 1) {
+    GPU_framebuffer_bind(fbl->shadow_accum_fb);
+    GPU_framebuffer_clear_color(fbl->shadow_accum_fb, clear);
+  }
+
+  /* Create Pass and shgroup. */
+  DRW_PASS_CREATE(psl->shadow_accum_pass,
+                  DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_ALWAYS | DRW_STATE_BLEND_ADD_FULL);
+  DRWShadingGroup *grp = DRW_shgroup_create(e_data.shadow_accum_sh, psl->shadow_accum_pass);
+  DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
+  DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
+  DRW_shgroup_uniform_block(grp, "probe_block", sldata->probe_ubo);
+  DRW_shgroup_uniform_block(grp, "grid_block", sldata->grid_ubo);
+  DRW_shgroup_uniform_block(grp, "planar_block", sldata->planar_ubo);
+  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_uniform_texture_ref(grp, "shadowCubeTexture", &sldata->shadow_cube_pool);
+  DRW_shgroup_uniform_texture_ref(grp, "shadowCascadeTexture", &sldata->shadow_cascade_pool);
+
+  DRW_shgroup_call(grp, DRW_cache_fullscreen_quad_get(), NULL);
+}
+
+void EEVEE_shadow_output_accumulate(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data *vedata)
+{
+  EEVEE_FramebufferList *fbl = vedata->fbl;
+  EEVEE_PassList *psl = vedata->psl;
+
+  if (fbl->shadow_accum_fb != NULL) {
+    GPU_framebuffer_bind(fbl->shadow_accum_fb);
+    DRW_draw_pass(psl->shadow_accum_pass);
+
+    /* Restore */
+    GPU_framebuffer_bind(fbl->main_fb);
+  }
+}
+
+/* \} */
+
 void EEVEE_shadows_free(void)
 {
   DRW_SHADER_FREE_SAFE(e_data.shadow_sh);
+  DRW_SHADER_FREE_SAFE(e_data.shadow_accum_sh);
 }