Eevee: internal support for arbitrary number of volume grids

This has no user visible impact yet since smoke volumes only support a fixed
set of attributes, but will become important with the new volume object.

For GPU shader compilation, volume grids are now handled separately from
image textures. They are somewhere between a vertex attribute and an image
texture, basically an attribute that is stored as a texture.

Differential Revision: https://developer.blender.org/D6952

2 files changed, 39 insertions, 18 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index a37c063adf6..05127585e6c 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -776,6 +776,7 @@ struct GPUMaterial *EEVEE_material_world_lightprobe_get(struct Scene *scene, Wor
                                       wo,
                                       engine,
                                       options,
+                                      false,
                                       e_data.vert_background_shader_str,
                                       NULL,
                                       e_data.frag_shader_lib,
@@ -796,6 +797,7 @@ struct GPUMaterial *EEVEE_material_world_background_get(struct Scene *scene, Wor
                                       wo,
                                       engine,
                                       options,
+                                      false,
                                       e_data.vert_background_shader_str,
                                       NULL,
                                       e_data.frag_shader_lib,
@@ -819,6 +821,7 @@ struct GPUMaterial *EEVEE_material_world_volume_get(struct Scene *scene, World *
                                      wo,
                                      engine,
                                      options,
+                                     true,
                                      e_data.vert_volume_shader_str,
                                      e_data.geom_volume_shader_str,
                                      e_data.volume_shader_lib,
@@ -853,6 +856,7 @@ struct GPUMaterial *EEVEE_material_mesh_get(struct Scene *scene,
                                         ma,
                                         engine,
                                         options,
+                                        false,
                                         e_data.vert_shader_str,
                                         NULL,
                                         e_data.frag_shader_lib,
@@ -880,6 +884,7 @@ struct GPUMaterial *EEVEE_material_mesh_volume_get(struct Scene *scene, Material
                                         ma,
                                         engine,
                                         options,
+                                        true,
                                         e_data.vert_volume_shader_str,
                                         e_data.geom_volume_shader_str,
                                         e_data.volume_shader_lib,
@@ -916,6 +921,7 @@ struct GPUMaterial *EEVEE_material_mesh_depth_get(struct Scene *scene,
                                         ma,
                                         engine,
                                         options,
+                                        false,
                                         (is_shadow) ? e_data.vert_shadow_shader_str :
                                                       e_data.vert_shader_str,
                                         NULL,
@@ -945,6 +951,7 @@ struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma)
                                         ma,
                                         engine,
                                         options,
+                                        false,
                                         e_data.vert_shader_str,
                                         NULL,
                                         e_data.frag_shader_lib,
@@ -1919,7 +1926,7 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
      * to know if the material has a "volume nodetree".
      */
     bool use_volume_material = (gpumat_array[0] &&
-                                GPU_material_use_domain_volume(gpumat_array[0]));
+                                GPU_material_has_volume_output(gpumat_array[0]));
 
     if ((ob->dt >= OB_SOLID) || DRW_state_is_image_render()) {
       /* Get per-material split surface */
@@ -1968,7 +1975,7 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
           /* Do not render surface if we are rendering a volume object
            * and do not have a surface closure. */
           if (use_volume_material &&
-              (gpumat_array[i] && !GPU_material_use_domain_surface(gpumat_array[i]))) {
+              (gpumat_array[i] && !GPU_material_has_surface_output(gpumat_array[i]))) {
             continue;
           }
 
diff --git a/source/blender/draw/engines/eevee/eevee_volumes.c b/source/blender/draw/engines/eevee/eevee_volumes.c
index dcb8b04fbcd..efe2ef5fc17 100644
--- a/source/blender/draw/engines/eevee/eevee_volumes.c
+++ b/source/blender/draw/engines/eevee/eevee_volumes.c
@@ -351,7 +351,7 @@ void EEVEE_volumes_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
       !LOOK_DEV_STUDIO_LIGHT_ENABLED(draw_ctx->v3d)) {
     struct GPUMaterial *mat = EEVEE_material_world_volume_get(scene, wo);
 
-    if (GPU_material_use_domain_volume(mat)) {
+    if (GPU_material_has_volume_output(mat)) {
       grp = DRW_shgroup_material_create(mat, psl->volumetric_world_ps);
     }
 
@@ -367,10 +367,11 @@ void EEVEE_volumes_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
           grp, "renderpass_block", EEVEE_material_default_render_pass_ubo_get(sldata));
 
       /* Fix principle volumetric not working with world materials. */
-      DRW_shgroup_uniform_texture(grp, "sampdensity", e_data.dummy_density);
-      DRW_shgroup_uniform_texture(grp, "sampcolor", e_data.dummy_density);
-      DRW_shgroup_uniform_texture(grp, "sampflame", e_data.dummy_flame);
-      DRW_shgroup_uniform_vec2_copy(grp, "unftemperature", (float[2]){0.0f, 1.0f});
+      ListBase gpu_grids = GPU_material_volume_grids(mat);
+      for (GPUMaterialVolumeGrid *gpu_grid = gpu_grids.first; gpu_grid;
+           gpu_grid = gpu_grid->next) {
+        DRW_shgroup_uniform_texture(grp, gpu_grid->sampler_name, e_data.dummy_density);
+      }
 
       DRW_shgroup_call_procedural_triangles(grp, NULL, common_data->vol_tex_size[2]);
 
@@ -446,6 +447,7 @@ void EEVEE_volumes_cache_object_add(EEVEE_ViewLayerData *sldata,
   DRW_shgroup_uniform_vec3(grp, "volumeOrcoLoc", texcoloc, 1);
   DRW_shgroup_uniform_vec3(grp, "volumeOrcoSize", texcosize, 1);
 
+  ListBase gpu_grids = GPU_material_volume_grids(mat);
   /* Smoke Simulation */
   if (((ob->base_flag & BASE_FROM_DUPLI) == 0) &&
       (md = modifiers_findByType(ob, eModifierType_Fluid)) &&
@@ -477,12 +479,25 @@ void EEVEE_volumes_cache_object_add(EEVEE_ViewLayerData *sldata,
       BLI_addtail(&e_data.smoke_domains, BLI_genericNodeN(mmd));
     }
 
-    DRW_shgroup_uniform_texture_ref(
-        grp, "sampdensity", mds->tex_density ? &mds->tex_density : &e_data.dummy_density);
-    DRW_shgroup_uniform_texture_ref(
-        grp, "sampcolor", mds->tex_color ? &mds->tex_color : &e_data.dummy_density);
-    DRW_shgroup_uniform_texture_ref(
-        grp, "sampflame", mds->tex_flame ? &mds->tex_flame : &e_data.dummy_flame);
+    for (GPUMaterialVolumeGrid *gpu_grid = gpu_grids.first; gpu_grid; gpu_grid = gpu_grid->next) {
+      if (STREQ(gpu_grid->name, "density")) {
+        DRW_shgroup_uniform_texture_ref(grp,
+                                        gpu_grid->sampler_name,
+                                        mds->tex_density ? &mds->tex_density :
+                                                           &e_data.dummy_density);
+      }
+      else if (STREQ(gpu_grid->name, "color")) {
+        DRW_shgroup_uniform_texture_ref(
+            grp, gpu_grid->sampler_name, mds->tex_color ? &mds->tex_color : &e_data.dummy_density);
+      }
+      else if (STREQ(gpu_grid->name, "flame") || STREQ(gpu_grid->name, "temperature")) {
+        DRW_shgroup_uniform_texture_ref(
+            grp, gpu_grid->sampler_name, mds->tex_flame ? &mds->tex_flame : &e_data.dummy_flame);
+      }
+      else {
+        DRW_shgroup_uniform_texture_ref(grp, gpu_grid->sampler_name, &e_data.dummy_density);
+      }
+    }
 
     /* Constant Volume color. */
     bool use_constant_color = ((mds->active_fields & FLUID_DOMAIN_ACTIVE_COLORS) == 0 &&
@@ -492,14 +507,13 @@ void EEVEE_volumes_cache_object_add(EEVEE_ViewLayerData *sldata,
         grp, "volumeColor", (use_constant_color) ? mds->active_color : white, 1);
 
     /* Output is such that 0..1 maps to 0..1000K */
-    DRW_shgroup_uniform_vec2(grp, "unftemperature", &mds->flame_ignition, 1);
+    DRW_shgroup_uniform_vec2(grp, "volumeTemperature", &mds->flame_ignition, 1);
   }
   else {
-    DRW_shgroup_uniform_texture(grp, "sampdensity", e_data.dummy_density);
-    DRW_shgroup_uniform_texture(grp, "sampcolor", e_data.dummy_density);
-    DRW_shgroup_uniform_texture(grp, "sampflame", e_data.dummy_flame);
+    for (GPUMaterialVolumeGrid *gpu_grid = gpu_grids.first; gpu_grid; gpu_grid = gpu_grid->next) {
+      DRW_shgroup_uniform_texture(grp, gpu_grid->sampler_name, e_data.dummy_density);
+    }
     DRW_shgroup_uniform_vec3(grp, "volumeColor", white, 1);
-    DRW_shgroup_uniform_vec2(grp, "unftemperature", (float[2]){0.0f, 1.0f}, 1);
   }
 
   /* TODO Reduce to number of slices intersecting. */