Fix T77267: Render EEVEE AO pass when AO disabled.

In EEVEE the AO renderpass influenced other render passes. Until now the
pass wasn't selectable when AO was disabled in the scene to remove these
render artifacts.

This patch allows rendering EEVEE AO pass without enabling it in the
scene. It does this by binding a fallback texture that is used by the
surface shaders.

Reviewed By: Clément Foucault

Differential Revision: https://developer.blender.org/D7956

4 files changed, 47 insertions, 60 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_occlusion.c b/source/blender/draw/engines/eevee/eevee_occlusion.c
index 9aae801197f..052fb485b19 100644
--- a/source/blender/draw/engines/eevee/eevee_occlusion.c
+++ b/source/blender/draw/engines/eevee/eevee_occlusion.c
@@ -78,7 +78,8 @@ int EEVEE_occlusion_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
     e_data.dummy_horizon_tx = DRW_texture_create_2d(1, 1, GPU_RGBA8, DRW_TEX_WRAP, pixel);
   }
 
-  if (scene_eval->eevee.flag & SCE_EEVEE_GTAO_ENABLED) {
+  if (scene_eval->eevee.flag & SCE_EEVEE_GTAO_ENABLED ||
+      stl->g_data->render_passes & EEVEE_RENDER_PASS_AO) {
     const float *viewport_size = DRW_viewport_size_get();
     const int fs_size[2] = {(int)viewport_size[0], (int)viewport_size[1]};
 
@@ -101,10 +102,11 @@ int EEVEE_occlusion_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 
     common_data->ao_bounce_fac = (scene_eval->eevee.flag & SCE_EEVEE_GTAO_BOUNCE) ? 1.0f : 0.0f;
 
-    effects->gtao_horizons = DRW_texture_pool_query_2d(
+    effects->gtao_horizons_renderpass = DRW_texture_pool_query_2d(
         fs_size[0], fs_size[1], GPU_RGBA8, &draw_engine_eevee_type);
     GPU_framebuffer_ensure_config(
-        &fbl->gtao_fb, {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(effects->gtao_horizons)});
+        &fbl->gtao_fb,
+        {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(effects->gtao_horizons_renderpass)});
 
     if (G.debug_value == 6) {
       effects->gtao_horizons_debug = DRW_texture_pool_query_2d(
@@ -117,10 +119,15 @@ int EEVEE_occlusion_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
       effects->gtao_horizons_debug = NULL;
     }
 
+    effects->gtao_horizons = (scene_eval->eevee.flag & SCE_EEVEE_GTAO_ENABLED) ?
+                                 effects->gtao_horizons_renderpass :
+                                 e_data.dummy_horizon_tx;
+
     return EFFECT_GTAO | EFFECT_NORMAL_BUFFER;
   }
 
   /* Cleanup */
+  effects->gtao_horizons_renderpass = e_data.dummy_horizon_tx;
   effects->gtao_horizons = e_data.dummy_horizon_tx;
   GPU_FRAMEBUFFER_FREE_SAFE(fbl->gtao_fb);
   common_data->ao_settings = 0.0f;
@@ -136,45 +143,41 @@ void EEVEE_occlusion_output_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata
   EEVEE_PassList *psl = vedata->psl;
   EEVEE_EffectsInfo *effects = stl->effects;
 
-  const DRWContextState *draw_ctx = DRW_context_state_get();
-  const Scene *scene_eval = DEG_get_evaluated_scene(draw_ctx->depsgraph);
-
-  if (scene_eval->eevee.flag & SCE_EEVEE_GTAO_ENABLED) {
-    const eGPUTextureFormat texture_format = (tot_samples > 128) ? GPU_R32F : GPU_R16F;
+  const eGPUTextureFormat texture_format = (tot_samples > 128) ? GPU_R32F : GPU_R16F;
 
-    DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
-    const float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
-
-    /* Should be enough precision for many samples. */
-    DRW_texture_ensure_fullscreen_2d(&txl->ao_accum, texture_format, 0);
+  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+  const float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 
-    GPU_framebuffer_ensure_config(&fbl->ao_accum_fb,
-                                  {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(txl->ao_accum)});
+  /* Should be enough precision for many samples. */
+  DRW_texture_ensure_fullscreen_2d(&txl->ao_accum, texture_format, 0);
 
-    /* Clear texture. */
-    if (effects->taa_current_sample == 1) {
-      GPU_framebuffer_bind(fbl->ao_accum_fb);
-      GPU_framebuffer_clear_color(fbl->ao_accum_fb, clear);
-    }
+  GPU_framebuffer_ensure_config(&fbl->ao_accum_fb,
+                                {GPU_ATTACHMENT_NONE, GPU_ATTACHMENT_TEXTURE(txl->ao_accum)});
 
-    /* Accumulation pass */
-    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ADD;
-    DRW_PASS_CREATE(psl->ao_accum_ps, state);
-    DRWShadingGroup *grp = DRW_shgroup_create(e_data.gtao_debug_sh, psl->ao_accum_ps);
-    DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
-    DRW_shgroup_uniform_texture_ref(grp, "maxzBuffer", &txl->maxzbuffer);
-    DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
-    DRW_shgroup_uniform_texture_ref(grp, "normalBuffer", &effects->ssr_normal_input);
-    DRW_shgroup_uniform_texture_ref(grp, "horizonBuffer", &effects->gtao_horizons);
-    DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
-    DRW_shgroup_uniform_block(grp, "renderpass_block", sldata->renderpass_ubo.combined);
-    DRW_shgroup_call(grp, DRW_cache_fullscreen_quad_get(), NULL);
+  /* Clear texture. */
+  if (effects->taa_current_sample == 1) {
+    GPU_framebuffer_bind(fbl->ao_accum_fb);
+    GPU_framebuffer_clear_color(fbl->ao_accum_fb, clear);
   }
-  else {
-    /* Cleanup to release memory */
-    DRW_TEXTURE_FREE_SAFE(txl->ao_accum);
-    GPU_FRAMEBUFFER_FREE_SAFE(fbl->ao_accum_fb);
+
+  /* Clear texture. */
+  if (DRW_state_is_image_render() || effects->taa_current_sample == 1) {
+    GPU_framebuffer_bind(fbl->ao_accum_fb);
+    GPU_framebuffer_clear_color(fbl->ao_accum_fb, clear);
   }
+
+  /* Accumulation pass */
+  DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ADD;
+  DRW_PASS_CREATE(psl->ao_accum_ps, state);
+  DRWShadingGroup *grp = DRW_shgroup_create(e_data.gtao_debug_sh, psl->ao_accum_ps);
+  DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
+  DRW_shgroup_uniform_texture_ref(grp, "maxzBuffer", &txl->maxzbuffer);
+  DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
+  DRW_shgroup_uniform_texture_ref(grp, "normalBuffer", &effects->ssr_normal_input);
+  DRW_shgroup_uniform_texture_ref(grp, "horizonBuffer", &effects->gtao_horizons_renderpass);
+  DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
+  DRW_shgroup_uniform_block(grp, "renderpass_block", sldata->renderpass_ubo.combined);
+  DRW_shgroup_call(grp, DRW_cache_fullscreen_quad_get(), NULL);
 }
 
 void EEVEE_occlusion_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
@@ -225,7 +228,7 @@ void EEVEE_occlusion_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
       DRW_shgroup_uniform_texture_ref(grp, "maxzBuffer", &txl->maxzbuffer);
       DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
       DRW_shgroup_uniform_texture_ref(grp, "normalBuffer", &effects->ssr_normal_input);
-      DRW_shgroup_uniform_texture_ref(grp, "horizonBuffer", &effects->gtao_horizons);
+      DRW_shgroup_uniform_texture_ref(grp, "horizonBuffer", &effects->gtao_horizons_renderpass);
       DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
       DRW_shgroup_uniform_block(grp, "renderpass_block", sldata->renderpass_ubo.combined);
       DRW_shgroup_call(grp, quad, NULL);
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index 1e2de521cdf..40d7676c38c 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -679,8 +679,9 @@ typedef struct EEVEE_EffectsInfo {
   struct DRWView *taa_view;
   /* Ambient Occlusion */
   int ao_depth_layer;
-  struct GPUTexture *ao_src_depth;  /* pointer copy */
-  struct GPUTexture *gtao_horizons; /* Textures from pool */
+  struct GPUTexture *ao_src_depth;             /* pointer copy */
+  struct GPUTexture *gtao_horizons;            /* Textures from pool */
+  struct GPUTexture *gtao_horizons_renderpass; /* Texture when rendering render pass */
   struct GPUTexture *gtao_horizons_debug;
   /* Motion Blur */
   float current_ndc_to_world[4][4];
diff --git a/source/blender/draw/engines/eevee/eevee_render.c b/source/blender/draw/engines/eevee/eevee_render.c
index 21a4013e309..65a856c39e1 100644
--- a/source/blender/draw/engines/eevee/eevee_render.c
+++ b/source/blender/draw/engines/eevee/eevee_render.c
@@ -359,11 +359,6 @@ static void eevee_render_result_occlusion(RenderLayer *rl,
                                           EEVEE_Data *vedata,
                                           EEVEE_ViewLayerData *sldata)
 {
-  if ((vedata->stl->effects->enabled_effects & EFFECT_GTAO) == 0) {
-    /* AO is not enabled. */
-    return;
-  }
-
   if ((vedata->stl->g_data->render_passes & EEVEE_RENDER_PASS_AO) != 0) {
     EEVEE_renderpasses_postprocess(sldata, vedata, EEVEE_RENDER_PASS_AO);
     eevee_render_color_result(
diff --git a/source/blender/draw/engines/eevee/eevee_renderpasses.c b/source/blender/draw/engines/eevee/eevee_renderpasses.c
index 089d8b7a287..55fe5882211 100644
--- a/source/blender/draw/engines/eevee/eevee_renderpasses.c
+++ b/source/blender/draw/engines/eevee/eevee_renderpasses.c
@@ -90,12 +90,8 @@ void EEVEE_renderpasses_init(EEVEE_Data *vedata)
   if (v3d) {
     const Scene *scene = draw_ctx->scene;
     eViewLayerEEVEEPassType render_pass = v3d->shading.render_pass;
-    if (render_pass == EEVEE_RENDER_PASS_AO &&
-        ((scene->eevee.flag & SCE_EEVEE_GTAO_ENABLED) == 0)) {
-      render_pass = EEVEE_RENDER_PASS_COMBINED;
-    }
-    else if (render_pass == EEVEE_RENDER_PASS_BLOOM &&
-             ((scene->eevee.flag & SCE_EEVEE_BLOOM_ENABLED) == 0)) {
+    if (render_pass == EEVEE_RENDER_PASS_BLOOM &&
+        ((scene->eevee.flag & SCE_EEVEE_BLOOM_ENABLED) == 0)) {
       render_pass = EEVEE_RENDER_PASS_COMBINED;
     }
     g_data->render_passes = render_pass;
@@ -392,8 +388,6 @@ void EEVEE_renderpasses_draw(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
       ((stl->g_data->render_passes & EEVEE_RENDERPASSES_LIGHT_PASS) != 0) ?
           (stl->g_data->render_passes & EEVEE_RENDERPASSES_LIGHT_PASS) :
           stl->g_data->render_passes;
-  const DRWContextState *draw_ctx = DRW_context_state_get();
-  const Scene *scene_eval = DEG_get_evaluated_scene(draw_ctx->depsgraph);
 
   bool is_valid = (render_pass & EEVEE_RENDERPASSES_ALL) > 0;
   bool needs_color_transfer = (render_pass & EEVEE_RENDERPASSES_COLOR_PASS) > 0 &&
@@ -405,12 +399,6 @@ void EEVEE_renderpasses_draw(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
     is_valid = false;
   }
 
-  /* When SSS isn't available, but the pass is requested, we mark it as invalid */
-  if ((render_pass & EEVEE_RENDER_PASS_AO) != 0 &&
-      (scene_eval->eevee.flag & SCE_EEVEE_GTAO_ENABLED) == 0) {
-    is_valid = false;
-  }
-
   const int current_sample = stl->effects->taa_current_sample;
   const int total_samples = stl->effects->taa_total_sample;
   if ((render_pass & EEVEE_RENDERPASSES_POST_PROCESS_ON_FIRST_SAMPLE) &&
@@ -462,10 +450,10 @@ void EEVEE_renderpasses_draw_debug(EEVEE_Data *vedata)
       tx = txl->color_double_buffer;
       break;
     case 6:
-      tx = effects->gtao_horizons;
+      tx = effects->gtao_horizons_renderpass;
       break;
     case 7:
-      tx = effects->gtao_horizons;
+      tx = effects->gtao_horizons_renderpass;
       break;
     case 8:
       tx = effects->sss_irradiance;