UI: Adaptive HDRI preview resolution

HDRI preview should have resolution dependent on dpi, viewport scale and HDRI gizmo size.
This patch uses a LOD to render a more round sphere.

Reviewed By: Jeroen Bakker

Differential Revision: https://developer.blender.org/D9382

source/blender/draw/engines/eevee/eevee_lookdev.c

@@ -65,7 +65,8 @@ static void eevee_lookdev_hdri_preview_init(EEVEE_Data *vedata, EEVEE_ViewLayerD
   Scene *scene = draw_ctx->scene;
   DRWShadingGroup *grp;
 
-  struct GPUBatch *sphere = DRW_cache_sphere_get();
+  const EEVEE_EffectsInfo *effects = vedata->stl->effects;
+  struct GPUBatch *sphere = DRW_cache_sphere_get(effects->sphere_lod);
   int mat_options = VAR_MAT_MESH | VAR_MAT_LOOKDEV;
 
   DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_ALWAYS |
@@ -126,6 +127,19 @@ void EEVEE_lookdev_init(EEVEE_Data *vedata)
 
     if (sphere_size != effects->sphere_size || rect->xmax != effects->anchor[0] ||
         rect->ymin != effects->anchor[1]) {
+      /* Make sphere resolution adaptive to viewport_scale, dpi and lookdev_sphere_size */
+      float res_scale = clamp_f(
+          (U.lookdev_sphere_size / 400.0f) * viewport_scale * U.dpi_fac, 0.1f, 1.0f);
+
+      if (res_scale > 0.7f) {
+        effects->sphere_lod = DRW_LOD_HIGH;
+      }
+      else if (res_scale > 0.25f) {
+        effects->sphere_lod = DRW_LOD_MEDIUM;
+      }
+      else {
+        effects->sphere_lod = DRW_LOD_LOW;
+      }
       /* If sphere size or anchor point moves, reset TAA to avoid ghosting issue.
        * This needs to happen early because we are changing taa_current_sample. */
       effects->sphere_size = sphere_size;

source/blender/draw/engines/eevee/eevee_private.h

@@ -734,6 +734,7 @@ typedef struct EEVEE_EffectsInfo {
   float prev_persmat[4][4];
   /* Lookdev */
   int sphere_size;
+  eDRWLevelOfDetail sphere_lod;
   int anchor[2];
   struct DRWView *lookdev_view;
   /* Bloom */

source/blender/draw/engines/overlay/overlay_extra.c

@@ -128,7 +128,7 @@ void OVERLAY_extra_cache_init(OVERLAY_Data *vedata)
       cb->empty_plain_axes = BUF_INSTANCE(grp_sub, format, DRW_cache_plain_axes_get());
       cb->empty_single_arrow = BUF_INSTANCE(grp_sub, format, DRW_cache_single_arrow_get());
       cb->empty_sphere = BUF_INSTANCE(grp_sub, format, DRW_cache_empty_sphere_get());
-      cb->empty_sphere_solid = BUF_INSTANCE(grp_sub, format, DRW_cache_sphere_get());
+      cb->empty_sphere_solid = BUF_INSTANCE(grp_sub, format, DRW_cache_sphere_get(DRW_LOD_LOW));
       cb->field_cone_limit = BUF_INSTANCE(grp_sub, format, DRW_cache_field_cone_limit_get());
       cb->field_curve = BUF_INSTANCE(grp_sub, format, DRW_cache_field_curve_get());
       cb->field_force = BUF_INSTANCE(grp_sub, format, DRW_cache_field_force_get());

source/blender/draw/intern/draw_cache.c

@@ -66,6 +66,17 @@
 #define VCLASS_EMPTY_AXES_SHADOW (1 << 13)
 #define VCLASS_EMPTY_SIZE (1 << 14)
 
+/* Sphere shape resolution */
+/* Low */
+#define DRW_SPHERE_SHAPE_LATITUDE_LOW 32
+#define DRW_SPHERE_SHAPE_LONGITUDE_LOW 24
+/* Medium */
+#define DRW_SPHERE_SHAPE_LATITUDE_MEDIUM 64
+#define DRW_SPHERE_SHAPE_LONGITUDE_MEDIUM 48
+/* High */
+#define DRW_SPHERE_SHAPE_LATITUDE_HIGH 80
+#define DRW_SPHERE_SHAPE_LONGITUDE_HIGH 60
+
 typedef struct Vert {
   float pos[3];
   int class;
@@ -88,7 +99,6 @@ static struct DRWShapeCache {
   GPUBatch *drw_quad;
   GPUBatch *drw_quad_wires;
   GPUBatch *drw_grid;
-  GPUBatch *drw_sphere;
   GPUBatch *drw_plain_axes;
   GPUBatch *drw_single_arrow;
   GPUBatch *drw_cube;
@@ -140,6 +150,7 @@ static struct DRWShapeCache {
   GPUBatch *drw_particle_circle;
   GPUBatch *drw_particle_axis;
   GPUBatch *drw_gpencil_dummy_quad;
+  GPUBatch *drw_sphere_lod[DRW_LOD_MAX];
 } SHC = {NULL};
 
 void DRW_shape_cache_free(void)
@@ -473,11 +484,30 @@ static void sphere_lat_lon_vert(GPUVertBuf *vbo, int *v_ofs, float lat, float lo
   (*v_ofs)++;
 }
 
-GPUBatch *DRW_cache_sphere_get(void)
+GPUBatch *DRW_cache_sphere_get(const eDRWLevelOfDetail level_of_detail)
 {
-  if (!SHC.drw_sphere) {
-    const int lat_res = 32;
-    const int lon_res = 24;
+  BLI_assert(level_of_detail >= DRW_LOD_LOW && level_of_detail < DRW_LOD_MAX);
+
+  if (!SHC.drw_sphere_lod[level_of_detail]) {
+    int lat_res;
+    int lon_res;
+
+    switch (level_of_detail) {
+      case DRW_LOD_LOW:
+        lat_res = DRW_SPHERE_SHAPE_LATITUDE_LOW;
+        lon_res = DRW_SPHERE_SHAPE_LONGITUDE_LOW;
+        break;
+      case DRW_LOD_MEDIUM:
+        lat_res = DRW_SPHERE_SHAPE_LATITUDE_MEDIUM;
+        lon_res = DRW_SPHERE_SHAPE_LONGITUDE_MEDIUM;
+        break;
+      case DRW_LOD_HIGH:
+        lat_res = DRW_SPHERE_SHAPE_LATITUDE_HIGH;
+        lon_res = DRW_SPHERE_SHAPE_LONGITUDE_HIGH;
+        break;
+      default:
+        return NULL;
+    }
 
     GPUVertFormat format = extra_vert_format();
     GPU_vertformat_attr_add(&format, "nor", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
@@ -508,9 +538,10 @@ GPUBatch *DRW_cache_sphere_get(void)
       }
     }
 
-    SHC.drw_sphere = GPU_batch_create_ex(GPU_PRIM_TRIS, vbo, NULL, GPU_BATCH_OWNS_VBO);
+    SHC.drw_sphere_lod[level_of_detail] = GPU_batch_create_ex(
+        GPU_PRIM_TRIS, vbo, NULL, GPU_BATCH_OWNS_VBO);
   }
-  return SHC.drw_sphere;
+  return SHC.drw_sphere_lod[level_of_detail];
 }
 
 /** \} */

source/blender/draw/intern/draw_cache.h

@@ -32,6 +32,15 @@ struct Volume;
 struct VolumeGrid;
 struct bGPDstroke;
 
+/* Shape resolution level of detail */
+typedef enum eDRWLevelOfDetail {
+  DRW_LOD_LOW = 0,
+  DRW_LOD_MEDIUM = 1,
+  DRW_LOD_HIGH = 2,
+
+  DRW_LOD_MAX, /* Max number of level of detail */
+} eDRWLevelOfDetail;
+
 void DRW_shape_cache_free(void);
 
 /* 3D cursor */
@@ -44,9 +53,10 @@ struct GPUBatch *DRW_cache_fullscreen_quad_get(void);
 struct GPUBatch *DRW_cache_quad_get(void);
 struct GPUBatch *DRW_cache_quad_wires_get(void);
 struct GPUBatch *DRW_cache_cube_get(void);
-struct GPUBatch *DRW_cache_sphere_get(void);
 struct GPUBatch *DRW_cache_normal_arrow_get(void);
 
+struct GPUBatch *DRW_cache_sphere_get(const eDRWLevelOfDetail level_of_detail);
+
 /* Dummy VBOs */
 struct GPUBatch *DRW_gpencil_dummy_buffer_get(void);