Volumetric: Debug Voxel Size and Location

When displaying the voxel size for an adaptive domain the resolution of the adaptive domain was used to calculate the world size of the voxel.
This patch changes this to use the initial size of the domain.

When using adaptive domain the overlay was not rendered in the right
place.

Thanks to sebbas for part of the patch!

Reviewed By: sebbas, fclem

Differential Revision: https://developer.blender.org/D6076

2 files changed, 25 insertions, 8 deletions

diff --git a/source/blender/draw/modes/object_mode.c b/source/blender/draw/modes/object_mode.c
index 11cef92c63c..70bccb4849c 100644
--- a/source/blender/draw/modes/object_mode.c
+++ b/source/blender/draw/modes/object_mode.c
@@ -2668,12 +2668,21 @@ static void DRW_shgroup_volume_extra(OBJECT_ShadingGroupList *sgl,
   DRW_object_wire_theme_get(ob, view_layer, &color);
 
   /* Small cube showing voxel size. */
+  float min[3];
+  madd_v3fl_v3fl_v3fl_v3i(min, sds->p0, sds->cell_size, sds->res_min);
   float voxel_cubemat[4][4] = {{0.0f}};
-  voxel_cubemat[0][0] = 1.0f / (float)sds->res[0];
-  voxel_cubemat[1][1] = 1.0f / (float)sds->res[1];
-  voxel_cubemat[2][2] = 1.0f / (float)sds->res[2];
+  /* scale small cube to voxel size */
+  voxel_cubemat[0][0] = 1.0f / (float)sds->base_res[0];
+  voxel_cubemat[1][1] = 1.0f / (float)sds->base_res[1];
+  voxel_cubemat[2][2] = 1.0f / (float)sds->base_res[2];
   voxel_cubemat[3][0] = voxel_cubemat[3][1] = voxel_cubemat[3][2] = -1.0f;
   voxel_cubemat[3][3] = 1.0f;
+  /* translate small cube to corner */
+  voxel_cubemat[3][0] = min[0];
+  voxel_cubemat[3][1] = min[1];
+  voxel_cubemat[3][2] = min[2];
+  voxel_cubemat[3][3] = 1.0f;
+  /* move small cube into the domain (otherwise its centered on vertex of domain object) */
   translate_m4(voxel_cubemat, 1.0f, 1.0f, 1.0f);
   mul_m4_m4m4(voxel_cubemat, ob->obmat, voxel_cubemat);
 
@@ -2709,6 +2718,9 @@ static void DRW_shgroup_volume_extra(OBJECT_ShadingGroupList *sgl,
   DRW_shgroup_uniform_texture(grp, "velocityZ", sds->tex_velocity_z);
   DRW_shgroup_uniform_float_copy(grp, "displaySize", sds->vector_scale);
   DRW_shgroup_uniform_float_copy(grp, "slicePosition", sds->slice_depth);
+  DRW_shgroup_uniform_vec3_copy(grp, "cellSize", sds->cell_size);
+  DRW_shgroup_uniform_vec3_copy(grp, "domainOriginOffset", sds->p0);
+  DRW_shgroup_uniform_ivec3_copy(grp, "adaptiveCellOffset", sds->res_min);
   DRW_shgroup_uniform_int_copy(grp, "sliceAxis", slice_axis);
   DRW_shgroup_call_procedural_lines(grp, ob, line_count);
 
diff --git a/source/blender/draw/modes/shaders/volume_velocity_vert.glsl b/source/blender/draw/modes/shaders/volume_velocity_vert.glsl
index e96a789b8b1..64f88bd74fa 100644
--- a/source/blender/draw/modes/shaders/volume_velocity_vert.glsl
+++ b/source/blender/draw/modes/shaders/volume_velocity_vert.glsl
@@ -6,6 +6,13 @@ uniform float displaySize = 1.0;
 uniform float slicePosition;
 uniform int sliceAxis; /* -1 is no slice, 0 is X, 1 is Y, 2 is Z. */
 
+/* SmokeDomainSettings.cell_size */
+uniform vec3 cellSize;
+/* SmokeDomainSettings.p0 */
+uniform vec3 domainOriginOffset;
+/* SmokeDomainSettings.res_min */
+uniform ivec3 adaptiveCellOffset;
+
 flat out vec4 finalColor;
 
 const vec3 corners[4] = vec3[4](vec3(0.0, 0.2, -0.5),
@@ -66,7 +73,6 @@ void main()
 #endif
 
   ivec3 volume_size = textureSize(velocityX, 0);
-  float voxel_size = 1.0 / float(max(max(volume_size.x, volume_size.y), volume_size.z));
 
   ivec3 cell_ofs = ivec3(0);
   ivec3 cell_div = volume_size;
@@ -89,8 +95,7 @@ void main()
   cell_co.z = cell / (cell_div.x * cell_div.y);
   cell_co += cell_ofs;
 
-  vec3 pos = (vec3(cell_co) + 0.5) / vec3(volume_size);
-  pos = pos * 2.0 - 1.0;
+  vec3 pos = domainOriginOffset + cellSize * (vec3(cell_co + adaptiveCellOffset) + 0.5);
 
   vec3 velocity;
   velocity.x = texelFetch(velocityX, cell_co, 0).r;
@@ -102,9 +107,9 @@ void main()
 #ifdef USE_NEEDLE
   mat3 rot_mat = rotation_from_vector(velocity);
   vec3 rotated_pos = rot_mat * corners[indices[gl_VertexID % 12]];
-  pos += rotated_pos * length(velocity) * displaySize * voxel_size;
+  pos += rotated_pos * length(velocity) * displaySize * cellSize;
 #else
-  pos += (((gl_VertexID % 2) == 1) ? velocity : vec3(0.0)) * displaySize * voxel_size;
+  pos += ((gl_VertexID % 2) == 1) ? velocity * displaySize * cellSize : vec3(0.0);
 #endif
 
   vec3 world_pos = point_object_to_world(pos);