Sculpt: Use uchar to store the sculpt mask in the GPU

Using a float to store and render the mask seems like a waste of memory
without any noticeable difference in the viewport for its use case.
After this commit, the mask and the face sets combined should take the
same amount of GPU memory than only the mask in previous versions.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7148

1 files changed, 22 insertions, 17 deletions

diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index d06d11023b6..168a3c83a91 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -116,7 +116,7 @@ void gpu_pbvh_init()
         &g_vbo_id.format, "nor", GPU_COMP_I16, 3, GPU_FETCH_INT_TO_FLOAT_UNIT);
     /* TODO: Do not allocate these `.msk` and `.col` when they are not used. */
     g_vbo_id.msk = GPU_vertformat_attr_add(
-        &g_vbo_id.format, "msk", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
+        &g_vbo_id.format, "msk", GPU_COMP_U8, 1, GPU_FETCH_INT_TO_FLOAT_UNIT);
     g_vbo_id.col = GPU_vertformat_attr_add(
         &g_vbo_id.format, "ac", GPU_COMP_U16, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
     g_vbo_id.fset = GPU_vertformat_attr_add(
@@ -264,15 +264,15 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
           copy_v3_v3(GPU_vertbuf_raw_step(&pos_step), v->co);
           copy_v3_v3_short(GPU_vertbuf_raw_step(&nor_step), v->no);
 
-          float mask;
+          uchar mask;
           if (show_mask) {
-            mask = vmask[vidx];
+            mask = (uchar)(vmask[vidx] * 255);
           }
           else {
             mask = 0.0f;
           }
-          *(float *)GPU_vertbuf_raw_step(&msk_step) = mask;
-          empty_mask = empty_mask && (mask == 0.0f);
+          *(uchar *)GPU_vertbuf_raw_step(&msk_step) = mask;
+          empty_mask = empty_mask && (mask == 0);
         }
 
         /* Face Sets. */
@@ -348,8 +348,10 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
           }
 
           float fmask = 0.0f;
+          uchar cmask = 0;
           if (show_mask) {
             fmask = (vmask[vtri[0]] + vmask[vtri[1]] + vmask[vtri[2]]) / 3.0f;
+            cmask = (uchar)(fmask * 255);
           }
 
           for (uint j = 0; j < 3; j++) {
@@ -357,8 +359,8 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
 
             copy_v3_v3(GPU_vertbuf_raw_step(&pos_step), v->co);
             copy_v3_v3_short(GPU_vertbuf_raw_step(&nor_step), no);
-            *(float *)GPU_vertbuf_raw_step(&msk_step) = fmask;
-            empty_mask = empty_mask && (fmask == 0.0f);
+            *(uchar *)GPU_vertbuf_raw_step(&msk_step) = cmask;
+            empty_mask = empty_mask && (cmask == 0);
             /* Face Sets. */
             memcpy(GPU_vertbuf_raw_step(&fset_step), face_set_color, sizeof(uchar) * 3);
 
@@ -730,8 +732,9 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
 
             if (has_mask && show_mask) {
               float fmask = *CCG_elem_mask(key, elem);
-              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &fmask);
-              empty_mask = empty_mask && (fmask == 0.0f);
+              uchar cmask = (uchar)(fmask * 255);
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &cmask);
+              empty_mask = empty_mask && (cmask == 0);
             }
 
             if (show_vcol) {
@@ -779,14 +782,15 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
             GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index + 3, no_short);
 
             if (has_mask && show_mask) {
-              float fsets = (*CCG_elem_mask(key, elems[0]) + *CCG_elem_mask(key, elems[1]) +
+              float fmask = (*CCG_elem_mask(key, elems[0]) + *CCG_elem_mask(key, elems[1]) +
                              *CCG_elem_mask(key, elems[2]) + *CCG_elem_mask(key, elems[3])) *
                             0.25f;
-              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 0, &fsets);
-              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 1, &fsets);
-              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 2, &fsets);
-              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 3, &fsets);
-              empty_mask = empty_mask && (fsets == 0.0f);
+              uchar cmask = (uchar)(fmask * 255);
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 0, &cmask);
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 1, &cmask);
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 2, &cmask);
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 3, &cmask);
+              empty_mask = empty_mask && (cmask == 0);
             }
 
             ushort vcol[4] = {USHRT_MAX, USHRT_MAX, USHRT_MAX, USHRT_MAX};
@@ -867,8 +871,9 @@ static void gpu_bmesh_vert_to_buffer_copy(BMVert *v,
 
   if (show_mask) {
     float effective_mask = fmask ? *fmask : BM_ELEM_CD_GET_FLOAT(v, cd_vert_mask_offset);
-    GPU_vertbuf_attr_set(vert_buf, g_vbo_id.msk, v_index, &effective_mask);
-    *empty_mask = *empty_mask && (effective_mask == 0.0f);
+    uchar cmask = (uchar)(effective_mask * 255);
+    GPU_vertbuf_attr_set(vert_buf, g_vbo_id.msk, v_index, &cmask);
+    *empty_mask = *empty_mask && (cmask == 0);
   }
 
   if (show_vcol) {