Fix multi material mesh

6 files changed, 43 insertions, 18 deletions

diff --git a/source/blender/draw/intern/draw_command.cc b/source/blender/draw/intern/draw_command.cc
index 31f7970cee3..569f56967a0 100644
--- a/source/blender/draw/intern/draw_command.cc
+++ b/source/blender/draw/intern/draw_command.cc
@@ -486,9 +486,10 @@ void DrawCommandBuf::bind(RecordingState &state,
 
     Draw &cmd = commands[header.index].draw;
 
-    int batch_vert_len, batch_inst_len;
+    int batch_vert_len, batch_vert_first, batch_base_index, batch_inst_len;
     /* Now that GPUBatches are guaranteed to be finished, extract their parameters. */
-    GPU_batch_draw_parameter_get(cmd.batch, &batch_vert_len, &batch_inst_len);
+    GPU_batch_draw_parameter_get(
+        cmd.batch, &batch_vert_len, &batch_vert_first, &batch_base_index, &batch_inst_len);
     /* Instancing attributes are not supported using the new pipeline since we use the base
      * instance to set the correct resource_id. Workaround is a storage_buf + gl_InstanceID. */
     BLI_assert(batch_inst_len == 1);
@@ -537,7 +538,11 @@ void DrawMultiBuf::bind(RecordingState &state,
 
     int batch_inst_len;
     /* Now that GPUBatches are guaranteed to be finished, extract their parameters. */
-    GPU_batch_draw_parameter_get(group.gpu_batch, &group.vertex_len, &batch_inst_len);
+    GPU_batch_draw_parameter_get(group.gpu_batch,
+                                 &group.vertex_len,
+                                 &group.vertex_first,
+                                 &group.base_index,
+                                 &batch_inst_len);
 
     /* Tag group as using index draw (changes indirect draw call structure). */
     if (group.gpu_batch->elem != nullptr) {
diff --git a/source/blender/draw/intern/draw_command_shared.hh b/source/blender/draw/intern/draw_command_shared.hh
index f412e609fbe..22d1facfb09 100644
--- a/source/blender/draw/intern/draw_command_shared.hh
+++ b/source/blender/draw/intern/draw_command_shared.hh
@@ -35,24 +35,30 @@ struct DrawGroup {
   uint front_facing_len;
 
   /** GPUBatch values to be copied to DrawCommand after sorting (if not overriden). */
-  int vertex_len; /** NOTE: Negative if using indexed draw. */
+  int vertex_len;
+  int vertex_first;
+  int base_index;
+
   /** Atomic counters used during command sorting. */
-  uint front_facing_counter;
-  uint back_facing_counter;
   uint total_counter;
 
-  /** For debug printing only. */
-  uint front_proto_len;
-  uint back_proto_len;
-
 #ifndef GPU_SHADER
   /* NOTE: Union just to make sure the struct has always the same size on all platform. */
   union {
-    /** Needed to create the correct draw call. */
-    GPUBatch *gpu_batch;
+    struct {
+      /** For debug printing only. */
+      uint front_proto_len;
+      uint back_proto_len;
+      /** Needed to create the correct draw call. */
+      GPUBatch *gpu_batch;
+    };
+    struct {
 #endif
-    uint2 _pad0;
+      uint front_facing_counter;
+      uint back_facing_counter;
+      uint _pad0, _pad1;
 #ifndef GPU_SHADER
+    };
   };
 #endif
 };
diff --git a/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl b/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl
index 031a35e4864..5adcb0b441d 100644
--- a/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl
+++ b/source/blender/draw/intern/shaders/draw_command_generate_comp.glsl
@@ -12,9 +12,9 @@ void write_draw_call(DrawGroup group, uint group_id)
 {
   DrawCommand cmd;
   cmd.vertex_len = abs(group.vertex_len);
-  cmd.vertex_first = 0;
-  if (group.vertex_len < 0) {
-    cmd.base_index = 0;
+  cmd.vertex_first = group.vertex_first;
+  if (group.base_index != -1) {
+    cmd.base_index = group.base_index;
     cmd.instance_first_indexed = group.start;
   }
   else {
diff --git a/source/blender/gpu/GPU_batch.h b/source/blender/gpu/GPU_batch.h
index ba3ab3265a1..8616df510a1 100644
--- a/source/blender/gpu/GPU_batch.h
+++ b/source/blender/gpu/GPU_batch.h
@@ -164,7 +164,8 @@ void GPU_batch_program_set_builtin_with_config(GPUBatch *batch,
 #define GPU_batch_texture_bind(batch, name, tex) \
   GPU_texture_bind(tex, GPU_shader_get_texture_binding((batch)->shader, name));
 
-void GPU_batch_draw_parameter_get(GPUBatch *batch, int *r_v_count, int *r_i_count);
+void GPU_batch_draw_parameter_get(
+    GPUBatch *batch, int *r_v_count, int *r_v_first, int *r_base_index, int *r_i_count);
 
 void GPU_batch_draw(GPUBatch *batch);
 void GPU_batch_draw_range(GPUBatch *batch, int v_first, int v_count);
diff --git a/source/blender/gpu/intern/gpu_batch.cc b/source/blender/gpu/intern/gpu_batch.cc
index 138e617fc0e..9092ad5110c 100644
--- a/source/blender/gpu/intern/gpu_batch.cc
+++ b/source/blender/gpu/intern/gpu_batch.cc
@@ -220,15 +220,20 @@ void GPU_batch_set_shader(GPUBatch *batch, GPUShader *shader)
 /** \name Drawing / Drawcall functions
  * \{ */
 
-void GPU_batch_draw_parameter_get(GPUBatch *gpu_batch, int *r_v_count, int *r_i_count)
+void GPU_batch_draw_parameter_get(
+    GPUBatch *gpu_batch, int *r_v_count, int *r_v_first, int *r_base_index, int *r_i_count)
 {
   Batch *batch = static_cast<Batch *>(gpu_batch);
 
   if (batch->elem) {
     *r_v_count = batch->elem_()->index_len_get();
+    *r_v_first = batch->elem_()->index_start_get();
+    *r_base_index = batch->elem_()->index_base_get();
   }
   else {
     *r_v_count = batch->verts_(0)->vertex_len;
+    *r_v_first = 0;
+    *r_base_index = -1;
   }
 
   int i_count = (batch->inst[0]) ? batch->inst_(0)->vertex_len : 1;
diff --git a/source/blender/gpu/intern/gpu_index_buffer_private.hh b/source/blender/gpu/intern/gpu_index_buffer_private.hh
index 6ce62ae852e..84903b05273 100644
--- a/source/blender/gpu/intern/gpu_index_buffer_private.hh
+++ b/source/blender/gpu/intern/gpu_index_buffer_private.hh
@@ -70,6 +70,14 @@ class IndexBuf {
      * They can lead to graphical glitches on some systems. (See T96892) */
     return is_empty_ ? 0 : index_len_;
   }
+  uint32_t index_start_get() const
+  {
+    return index_start_;
+  }
+  uint32_t index_base_get() const
+  {
+    return index_base_;
+  }
   /* Return size in byte of the drawable data buffer range. Actual buffer size might be bigger. */
   size_t size_get() const
   {