GPU: Replace `GPUMaterialVolumeGrid` by `GPUMaterialAttribute`

This is to make the codegen and shading nodes object type agnostic. This
is essential for flexibility of the engine to use the nodetree as it see
fits.

The essential volume attributes struct properties are moved to the
`GPUMaterialAttribute` which see its final input name set on creation.

The binding process is centralized into `draw_volume.cc` to avoid
duplicating the code between multiple engines. It mimics the hair attributes
process.

Volume object grid transforms and other per object uniforms are packed into
one UBO per object. The grid transform is now based on object which simplify
the matrix preparations.

This also gets rid of the double transforms and use object info orco factors
for volume objects.

Tagging @brecht because he did the initial implementation of Volume Grids.

9 files changed, 85 insertions, 223 deletions

diff --git a/source/blender/gpu/CMakeLists.txt b/source/blender/gpu/CMakeLists.txt
index 98d15a1024c..93030d6ab6e 100644
--- a/source/blender/gpu/CMakeLists.txt
+++ b/source/blender/gpu/CMakeLists.txt
@@ -370,7 +370,6 @@ set(GLSL_SRC
   shaders/material/gpu_shader_material_velvet.glsl
   shaders/material/gpu_shader_material_vertex_color.glsl
   shaders/material/gpu_shader_material_volume_absorption.glsl
-  shaders/material/gpu_shader_material_volume_info.glsl
   shaders/material/gpu_shader_material_volume_principled.glsl
   shaders/material/gpu_shader_material_volume_scatter.glsl
   shaders/material/gpu_shader_material_wireframe.glsl
diff --git a/source/blender/gpu/GPU_material.h b/source/blender/gpu/GPU_material.h
index f38b9681ad7..55fbe3f981f 100644
--- a/source/blender/gpu/GPU_material.h
+++ b/source/blender/gpu/GPU_material.h
@@ -109,10 +109,10 @@ typedef enum eGPUMaterialStatus {
   GPU_MAT_SUCCESS,
 } eGPUMaterialStatus;
 
-typedef enum eGPUVolumeDefaultValue {
-  GPU_VOLUME_DEFAULT_0,
-  GPU_VOLUME_DEFAULT_1,
-} eGPUVolumeDefaultValue;
+typedef enum eGPUDefaultValue {
+  GPU_DEFAULT_0 = 0,
+  GPU_DEFAULT_1,
+} eGPUDefaultValue;
 
 typedef struct GPUCodegenOutput {
   char *attr_load;
@@ -131,6 +131,10 @@ typedef void (*GPUCodegenCallbackFn)(void *thunk, GPUMaterial *mat, GPUCodegenOu
 GPUNodeLink *GPU_constant(const float *num);
 GPUNodeLink *GPU_uniform(const float *num);
 GPUNodeLink *GPU_attribute(GPUMaterial *mat, CustomDataType type, const char *name);
+GPUNodeLink *GPU_attribute_with_default(GPUMaterial *mat,
+                                        CustomDataType type,
+                                        const char *name,
+                                        eGPUDefaultValue default_value);
 GPUNodeLink *GPU_uniform_attribute(GPUMaterial *mat, const char *name, bool use_dupli);
 GPUNodeLink *GPU_image(GPUMaterial *mat,
                        struct Image *ima,
@@ -142,9 +146,7 @@ GPUNodeLink *GPU_image_tiled(GPUMaterial *mat,
                              eGPUSamplerState sampler_state);
 GPUNodeLink *GPU_image_tiled_mapping(GPUMaterial *mat, struct Image *ima, struct ImageUser *iuser);
 GPUNodeLink *GPU_color_band(GPUMaterial *mat, int size, float *pixels, float *row);
-GPUNodeLink *GPU_volume_grid(GPUMaterial *mat,
-                             const char *name,
-                             eGPUVolumeDefaultValue default_value);
+
 /**
  * Create an implementation defined differential calculation of a float function.
  * The given function should return a float.
@@ -255,9 +257,11 @@ void GPU_pass_cache_free(void);
 
 typedef struct GPUMaterialAttribute {
   struct GPUMaterialAttribute *next, *prev;
-  int type;      /* CustomDataType */
-  char name[64]; /* MAX_CUSTOMDATA_LAYER_NAME */
+  int type;                /* CustomDataType */
+  char name[64];           /* MAX_CUSTOMDATA_LAYER_NAME */
+  char input_name[12 + 1]; /* GPU_MAX_SAFE_ATTR_NAME + 1 */
   eGPUType gputype;
+  eGPUDefaultValue default_value; /* Only for volumes attributes. */
   int id;
   int users;
 } GPUMaterialAttribute;
@@ -274,18 +278,8 @@ typedef struct GPUMaterialTexture {
   int sampler_state; /* eGPUSamplerState */
 } GPUMaterialTexture;
 
-typedef struct GPUMaterialVolumeGrid {
-  struct GPUMaterialVolumeGrid *next, *prev;
-  char *name;
-  eGPUVolumeDefaultValue default_value;
-  char sampler_name[32];   /* Name of sampler in GLSL. */
-  char transform_name[32]; /* Name of 4x4 matrix in GLSL. */
-  int users;
-} GPUMaterialVolumeGrid;
-
 ListBase GPU_material_attributes(GPUMaterial *material);
 ListBase GPU_material_textures(GPUMaterial *material);
-ListBase GPU_material_volume_grids(GPUMaterial *material);
 
 typedef struct GPUUniformAttr {
   struct GPUUniformAttr *next, *prev;
diff --git a/source/blender/gpu/intern/gpu_codegen.cc b/source/blender/gpu/intern/gpu_codegen.cc
index 8963fa45c96..048928b2312 100644
--- a/source/blender/gpu/intern/gpu_codegen.cc
+++ b/source/blender/gpu/intern/gpu_codegen.cc
@@ -49,7 +49,6 @@ using namespace blender::gpu::shader;
 
 struct GPUCodegenCreateInfo : ShaderCreateInfo {
   struct NameBuffer {
-    char attr_names[16][GPU_MAX_SAFE_ATTR_NAME + 1];
     char var_names[16][8];
   };
 
@@ -171,10 +170,6 @@ static std::ostream &operator<<(std::ostream &stream, const GPUInput *input)
       return stream << input->texture->sampler_name;
     case GPU_SOURCE_TEX_TILED_MAPPING:
       return stream << input->texture->tiled_mapping_name;
-    case GPU_SOURCE_VOLUME_GRID:
-      return stream << input->volume_grid->sampler_name;
-    case GPU_SOURCE_VOLUME_GRID_TRANSFORM:
-      return stream << input->volume_grid->transform_name;
     default:
       BLI_assert(0);
       return stream;
@@ -276,28 +271,6 @@ class GPUCodegen {
   }
 };
 
-static char attr_prefix_get(CustomDataType type)
-{
-  switch (type) {
-    case CD_MTFACE:
-      return 'u';
-    case CD_TANGENT:
-      return 't';
-    case CD_MCOL:
-    case CD_MLOOPCOL:
-      return 'c';
-    case CD_PROP_COLOR:
-      return 'c';
-    case CD_AUTO_FROM_NAME:
-      return 'a';
-    case CD_HAIRLENGTH:
-      return 'l';
-    default:
-      BLI_assert_msg(0, "GPUVertAttr Prefix type not found : This should not happen!");
-      return '\0';
-  }
-}
-
 void GPUCodegen::generate_attribs()
 {
   if (BLI_listbase_is_empty(&graph.attributes)) {
@@ -317,24 +290,9 @@ void GPUCodegen::generate_attribs()
 
   int slot = 15;
   LISTBASE_FOREACH (GPUMaterialAttribute *, attr, &graph.attributes) {
-
-    /* NOTE: Replicate changes to mesh_render_data_create() in draw_cache_impl_mesh.c */
-    if (attr->type == CD_ORCO) {
-      /* OPTI: orco is computed from local positions, but only if no modifier is present. */
-      STRNCPY(info.name_buffer->attr_names[slot], "orco");
-    }
-    else {
-      char *name = info.name_buffer->attr_names[slot];
-      name[0] = attr_prefix_get(static_cast<CustomDataType>(attr->type));
-      name[1] = '\0';
-      if (attr->name[0] != '\0') {
-        /* XXX FIXME: see notes in mesh_render_data_create() */
-        GPU_vertformat_safe_attr_name(attr->name, &name[1], GPU_MAX_SAFE_ATTR_NAME);
-      }
-    }
     SNPRINTF(info.name_buffer->var_names[slot], "v%d", attr->id);
 
-    blender::StringRefNull attr_name = info.name_buffer->attr_names[slot];
+    blender::StringRefNull attr_name = attr->input_name;
     blender::StringRefNull var_name = info.name_buffer->var_names[slot];
 
     eGPUType input_type, iface_type;
@@ -395,12 +353,6 @@ void GPUCodegen::generate_resources()
       info.sampler(0, ImageType::FLOAT_2D, tex->sampler_name, Frequency::BATCH);
     }
   }
-  /* Volume Grids. */
-  LISTBASE_FOREACH (GPUMaterialVolumeGrid *, grid, &graph.volume_grids) {
-    info.sampler(0, ImageType::FLOAT_3D, grid->sampler_name, Frequency::BATCH);
-    /* TODO(@fclem): Global uniform. To put in an UBO. */
-    info.push_constant(Type::MAT4, grid->transform_name);
-  }
 
   if (!BLI_listbase_is_empty(&ubo_inputs_)) {
     /* NOTE: generate_uniform_buffer() should have sorted the inputs before this. */
diff --git a/source/blender/gpu/intern/gpu_material.c b/source/blender/gpu/intern/gpu_material.c
index 711a3943a25..21e40a67d5e 100644
--- a/source/blender/gpu/intern/gpu_material.c
+++ b/source/blender/gpu/intern/gpu_material.c
@@ -219,11 +219,6 @@ ListBase GPU_material_textures(GPUMaterial *material)
   return material->graph.textures;
 }
 
-ListBase GPU_material_volume_grids(GPUMaterial *material)
-{
-  return material->graph.volume_grids;
-}
-
 GPUUniformAttrList *GPU_material_uniform_attributes(GPUMaterial *material)
 {
   GPUUniformAttrList *attrs = &material->graph.uniform_attrs;
diff --git a/source/blender/gpu/intern/gpu_node_graph.c b/source/blender/gpu/intern/gpu_node_graph.c
index d9143a12d5b..20551785535 100644
--- a/source/blender/gpu/intern/gpu_node_graph.c
+++ b/source/blender/gpu/intern/gpu_node_graph.c
@@ -20,6 +20,7 @@
 #include "BLI_utildefines.h"
 
 #include "GPU_texture.h"
+#include "GPU_vertex_format.h"
 
 #include "gpu_material_library.h"
 #include "gpu_node_graph.h"
@@ -102,14 +103,6 @@ static void gpu_node_input_link(GPUNode *node, GPUNodeLink *link, const eGPUType
       input->source = GPU_SOURCE_TEX_TILED_MAPPING;
       input->texture = link->texture;
       break;
-    case GPU_NODE_LINK_VOLUME_GRID:
-      input->source = GPU_SOURCE_VOLUME_GRID;
-      input->volume_grid = link->volume_grid;
-      break;
-    case GPU_NODE_LINK_VOLUME_GRID_TRANSFORM:
-      input->source = GPU_SOURCE_VOLUME_GRID_TRANSFORM;
-      input->volume_grid = link->volume_grid;
-      break;
     case GPU_NODE_LINK_ATTR:
       input->source = GPU_SOURCE_ATTR;
       input->attr = link->attr;
@@ -335,6 +328,45 @@ void gpu_node_graph_finalize_uniform_attrs(GPUNodeGraph *graph)
 
 /* Attributes and Textures */
 
+static char attr_prefix_get(CustomDataType type)
+{
+  switch (type) {
+    case CD_MTFACE:
+      return 'u';
+    case CD_TANGENT:
+      return 't';
+    case CD_MCOL:
+    case CD_MLOOPCOL:
+      return 'c';
+    case CD_PROP_COLOR:
+      return 'c';
+    case CD_AUTO_FROM_NAME:
+      return 'a';
+    case CD_HAIRLENGTH:
+      return 'l';
+    default:
+      BLI_assert_msg(0, "GPUVertAttr Prefix type not found : This should not happen!");
+      return '\0';
+  }
+}
+
+static void attr_input_name(GPUMaterialAttribute *attr)
+{
+  /* NOTE: Replicate changes to mesh_render_data_create() in draw_cache_impl_mesh.c */
+  if (attr->type == CD_ORCO) {
+    /* OPTI: orco is computed from local positions, but only if no modifier is present. */
+    STRNCPY(attr->input_name, "orco");
+  }
+  else {
+    attr->input_name[0] = attr_prefix_get(attr->type);
+    attr->input_name[1] = '\0';
+    if (attr->name[0] != '\0') {
+      /* XXX FIXME: see notes in mesh_render_data_create() */
+      GPU_vertformat_safe_attr_name(attr->name, &attr->input_name[1], GPU_MAX_SAFE_ATTR_NAME);
+    }
+  }
+}
+
 /** Add a new varying attribute of given type and name. Returns NULL if out of slots. */
 static GPUMaterialAttribute *gpu_node_graph_add_attribute(GPUNodeGraph *graph,
                                                           CustomDataType type,
@@ -360,6 +392,7 @@ static GPUMaterialAttribute *gpu_node_graph_add_attribute(GPUNodeGraph *graph,
     attr = MEM_callocN(sizeof(*attr), __func__);
     attr->type = type;
     STRNCPY(attr->name, name);
+    attr_input_name(attr);
     attr->id = num_attributes;
     BLI_addtail(&graph->attributes, attr);
   }
@@ -443,35 +476,6 @@ static GPUMaterialTexture *gpu_node_graph_add_texture(GPUNodeGraph *graph,
   return tex;
 }
 
-static GPUMaterialVolumeGrid *gpu_node_graph_add_volume_grid(GPUNodeGraph *graph,
-                                                             const char *name,
-                                                             eGPUVolumeDefaultValue default_value)
-{
-  /* Find existing volume grid. */
-  int num_grids = 0;
-  GPUMaterialVolumeGrid *grid = graph->volume_grids.first;
-  for (; grid; grid = grid->next) {
-    if (STREQ(grid->name, name) && grid->default_value == default_value) {
-      break;
-    }
-    num_grids++;
-  }
-
-  /* Add new requested volume grid. */
-  if (grid == NULL) {
-    grid = MEM_callocN(sizeof(*grid), __func__);
-    grid->name = BLI_strdup(name);
-    grid->default_value = default_value;
-    BLI_snprintf(grid->sampler_name, sizeof(grid->sampler_name), "vsamp%d", num_grids);
-    BLI_snprintf(grid->transform_name, sizeof(grid->transform_name), "vtfm%d", num_grids);
-    BLI_addtail(&graph->volume_grids, grid);
-  }
-
-  grid->users++;
-
-  return grid;
-}
-
 /* Creating Inputs */
 
 GPUNodeLink *GPU_attribute(GPUMaterial *mat, const CustomDataType type, const char *name)
@@ -496,6 +500,18 @@ GPUNodeLink *GPU_attribute(GPUMaterial *mat, const CustomDataType type, const ch
   return link;
 }
 
+GPUNodeLink *GPU_attribute_with_default(GPUMaterial *mat,
+                                        const CustomDataType type,
+                                        const char *name,
+                                        eGPUDefaultValue default_value)
+{
+  GPUNodeLink *link = GPU_attribute(mat, type, name);
+  if (link->link_type == GPU_NODE_LINK_ATTR) {
+    link->attr->default_value = default_value;
+  }
+  return link;
+}
+
 GPUNodeLink *GPU_uniform_attribute(GPUMaterial *mat, const char *name, bool use_dupli)
 {
   GPUNodeGraph *graph = gpu_material_node_graph(mat);
@@ -586,39 +602,6 @@ GPUNodeLink *GPU_color_band(GPUMaterial *mat, int size, float *pixels, float *ro
   return link;
 }
 
-GPUNodeLink *GPU_volume_grid(GPUMaterial *mat,
-                             const char *name,
-                             eGPUVolumeDefaultValue default_value)
-{
-  /* NOTE: this could be optimized by automatically merging duplicate
-   * lookups of the same attribute. */
-  GPUNodeGraph *graph = gpu_material_node_graph(mat);
-  GPUNodeLink *link = gpu_node_link_create();
-  link->link_type = GPU_NODE_LINK_VOLUME_GRID;
-  link->volume_grid = gpu_node_graph_add_volume_grid(graph, name, default_value);
-
-  GPUNodeLink *transform_link = gpu_node_link_create();
-  transform_link->link_type = GPU_NODE_LINK_VOLUME_GRID_TRANSFORM;
-  transform_link->volume_grid = link->volume_grid;
-  transform_link->volume_grid->users++;
-
-  GPUNodeLink *cos_link = GPU_attribute(mat, CD_ORCO, "");
-
-  /* Two special cases, where we adjust the output values of smoke grids to
-   * bring the into standard range without having to modify the grid values. */
-  if (STREQ(name, "color")) {
-    GPU_link(mat, "node_attribute_volume_color", link, transform_link, cos_link, &link);
-  }
-  else if (STREQ(name, "temperature")) {
-    GPU_link(mat, "node_attribute_volume_temperature", link, transform_link, cos_link, &link);
-  }
-  else {
-    GPU_link(mat, "node_attribute_volume", link, transform_link, cos_link, &link);
-  }
-
-  return link;
-}
-
 /* Creating Nodes */
 
 bool GPU_link(GPUMaterial *mat, const char *name, ...)
@@ -767,9 +750,6 @@ static void gpu_inputs_free(ListBase *inputs)
     else if (ELEM(input->source, GPU_SOURCE_TEX, GPU_SOURCE_TEX_TILED_MAPPING)) {
       input->texture->users--;
     }
-    else if (ELEM(input->source, GPU_SOURCE_VOLUME_GRID, GPU_SOURCE_VOLUME_GRID_TRANSFORM)) {
-      input->volume_grid->users--;
-    }
 
     if (input->link) {
       gpu_node_link_free(input->link);
@@ -816,10 +796,6 @@ void gpu_node_graph_free(GPUNodeGraph *graph)
   BLI_freelistN(&graph->material_functions);
   gpu_node_graph_free_nodes(graph);
 
-  LISTBASE_FOREACH (GPUMaterialVolumeGrid *, grid, &graph->volume_grids) {
-    MEM_SAFE_FREE(grid->name);
-  }
-  BLI_freelistN(&graph->volume_grids);
   BLI_freelistN(&graph->textures);
   BLI_freelistN(&graph->attributes);
   GPU_uniform_attr_list_free(&graph->uniform_attrs);
@@ -894,14 +870,6 @@ void gpu_node_graph_prune_unused(GPUNodeGraph *graph)
     }
   }
 
-  for (GPUMaterialVolumeGrid *grid = graph->volume_grids.first, *next = NULL; grid; grid = next) {
-    next = grid->next;
-    if (grid->users == 0) {
-      MEM_SAFE_FREE(grid->name);
-      BLI_freelinkN(&graph->volume_grids, grid);
-    }
-  }
-
   GPUUniformAttrList *uattrs = &graph->uniform_attrs;
 
   LISTBASE_FOREACH_MUTABLE (GPUUniformAttr *, attr, &uattrs->list) {
diff --git a/source/blender/gpu/intern/gpu_node_graph.h b/source/blender/gpu/intern/gpu_node_graph.h
index 024119e1c24..ae472d5b7aa 100644
--- a/source/blender/gpu/intern/gpu_node_graph.h
+++ b/source/blender/gpu/intern/gpu_node_graph.h
@@ -34,8 +34,6 @@ typedef enum eGPUDataSource {
   GPU_SOURCE_STRUCT,
   GPU_SOURCE_TEX,
   GPU_SOURCE_TEX_TILED_MAPPING,
-  GPU_SOURCE_VOLUME_GRID,
-  GPU_SOURCE_VOLUME_GRID_TRANSFORM,
   GPU_SOURCE_FUNCTION_CALL,
 } eGPUDataSource;
 
@@ -48,8 +46,6 @@ typedef enum {
   GPU_NODE_LINK_IMAGE,
   GPU_NODE_LINK_IMAGE_TILED,
   GPU_NODE_LINK_IMAGE_TILED_MAPPING,
-  GPU_NODE_LINK_VOLUME_GRID,
-  GPU_NODE_LINK_VOLUME_GRID_TRANSFORM,
   GPU_NODE_LINK_OUTPUT,
   GPU_NODE_LINK_UNIFORM,
   GPU_NODE_LINK_DIFFERENTIATE_FLOAT_FN,
@@ -90,8 +86,6 @@ struct GPUNodeLink {
     const float *data;
     /* GPU_NODE_LINK_COLORBAND */
     struct GPUTexture **colorband;
-    /* GPU_NODE_LINK_VOLUME_GRID */
-    struct GPUMaterialVolumeGrid *volume_grid;
     /* GPU_NODE_LINK_OUTPUT */
     struct GPUOutput *output;
     /* GPU_NODE_LINK_ATTR */
@@ -134,8 +128,6 @@ typedef struct GPUInput {
     struct GPUMaterialAttribute *attr;
     /* GPU_SOURCE_UNIFORM_ATTR */
     struct GPUUniformAttr *uniform_attr;
-    /* GPU_SOURCE_VOLUME_GRID | GPU_SOURCE_VOLUME_GRID_TRANSFORM */
-    struct GPUMaterialVolumeGrid *volume_grid;
     /* GPU_SOURCE_FUNCTION_CALL */
     char function_call[64];
   };
@@ -170,7 +162,6 @@ typedef struct GPUNodeGraph {
   /* Requested attributes and textures. */
   ListBase attributes;
   ListBase textures;
-  ListBase volume_grids;
 
   /* The list of uniform attributes. */
   GPUUniformAttrList uniform_attrs;
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
index faf37db3ea6..2ae53b35b3f 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
@@ -1,3 +1,17 @@
+
+void node_attribute_color(vec4 attr, out vec4 out_attr)
+{
+  out_attr = attr_load_color_post(attr);
+}
+
+void node_attribute_temperature(vec4 attr, out vec4 out_attr)
+{
+  out_attr.x = attr_load_temperature_post(attr.x);
+  out_attr.y = 0.0;
+  out_attr.z = 0.0;
+  out_attr.w = 1.0;
+}
+
 void node_attribute(
     vec4 attr, out vec4 outcol, out vec3 outvec, out float outf, out float outalpha)
 {
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
deleted file mode 100644
index 464cf5227b4..00000000000
--- a/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
+++ /dev/null
@@ -1,51 +0,0 @@
-
-/* Uniforms to convert smoke grid values into standard range. */
-uniform vec3 volumeColor = vec3(1.0);
-uniform vec2 volumeTemperature = vec2(0.0);
-
-/* Generic volume attribute. */
-void node_attribute_volume(sampler3D tex, mat4 transform, vec3 cos, out vec3 outvec)
-{
-  /* Optional per-grid transform. */
-  if (transform[3][3] != 0.0) {
-    cos = (transform * vec4(cos, 1.0)).xyz;
-  }
-
-  outvec = texture(tex, cos).rgb;
-}
-
-/* Special color attribute for smoke. */
-void node_attribute_volume_color(sampler3D tex, mat4 transform, vec3 cos, out vec3 outvec)
-{
-  /* Optional per-grid transform. */
-  if (transform[3][3] != 0.0) {
-    cos = (transform * vec4(cos, 1.0)).xyz;
-  }
-
-  /* Density is premultiplied for interpolation, divide it out here. */
-  vec4 value = texture(tex, cos).rgba;
-  if (value.a > 1e-8) {
-    value.rgb /= value.a;
-  }
-
-  outvec = value.rgb * volumeColor;
-}
-
-/* Special temperature attribute for smoke. */
-void node_attribute_volume_temperature(sampler3D tex, mat4 transform, vec3 cos, out float outf)
-{
-  /* Optional per-grid transform. */
-  if (transform[3][3] != 0.0) {
-    cos = (transform * vec4(cos, 1.0)).xyz;
-  }
-
-  float value = texture(tex, cos).r;
-  if (volumeTemperature.x < volumeTemperature.y) {
-    outf = (value > 0.01) ?
-               volumeTemperature.x + value * (volumeTemperature.y - volumeTemperature.x) :
-               0.0;
-  }
-  else {
-    outf = value;
-  }
-}
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_volume_principled.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_volume_principled.glsl
index 1127c34b3ac..21c4aba0ffe 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_volume_principled.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_volume_principled.glsl
@@ -10,9 +10,9 @@ void node_volume_principled(vec4 color,
                             vec4 blackbody_tint,
                             float temperature,
                             float weight,
-                            float density_attribute,
+                            vec4 density_attribute,
                             vec4 color_attribute,
-                            float temperature_attribute,
+                            vec4 temperature_attribute,
                             sampler1DArray spectrummap,
                             float layer,
                             out Closure result)
@@ -25,7 +25,7 @@ void node_volume_principled(vec4 color,
   density = max(density, 0.0);
 
   if (density > 1e-5) {
-    density = max(density * density_attribute, 0.0);
+    density = max(density * density_attribute.x, 0.0);
   }
 
   if (density > 1e-5) {
@@ -47,7 +47,7 @@ void node_volume_principled(vec4 color,
 
   if (blackbody_intensity > 1e-3) {
     /* Add temperature from attribute. */
-    float T = max(temperature * max(temperature_attribute, 0.0), 0.0);
+    float T = max(temperature * max(temperature_attribute.x, 0.0), 0.0);
 
     /* Stefan-Boltzman law. */
     float T2 = T * T;