Curves: use root/tip radius of the first curve in the viewport

Viewport drawing does not support a per point radius attribute yet.
Instead, it has a fixed set of radius parameters that are used for all
curves in the same object. Now those radii are retrieved from the
radius attribute of the points on the first curve. This allows users
to control the radius of curves to some degree until proper per-point
radius is supported.

1 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_curves.cc b/source/blender/draw/intern/draw_curves.cc
index 39d4845994f..749383edc6d 100644
--- a/source/blender/draw/intern/draw_curves.cc
+++ b/source/blender/draw/intern/draw_curves.cc
@@ -13,6 +13,9 @@
 #include "DNA_curves_types.h"
 #include "DNA_customdata_types.h"
 
+#include "BKE_curves.hh"
+#include "BKE_geometry_set.hh"
+
 #include "GPU_batch.h"
 #include "GPU_capabilities.h"
 #include "GPU_compute.h"
@@ -325,6 +328,21 @@ DRWShadingGroup *DRW_shgroup_curves_create_sub(Object *object,
   float hair_rad_tip = 0.0f;
   bool hair_close_tip = true;
 
+  /* Use the radius of the root and tip of the first curve for now. This is a workaround that we
+   * use for now because we can't use a per-point radius yet. */
+  Curves &curves_id = *static_cast<Curves *>(object->data);
+  const blender::bke::CurvesGeometry &curves = blender::bke::CurvesGeometry::wrap(
+      curves_id.geometry);
+  if (curves.curves_num() >= 1) {
+    CurveComponent curves_component;
+    curves_component.replace(&curves_id, GeometryOwnershipType::ReadOnly);
+    blender::VArray<float> radii = curves_component.attribute_get_for_read(
+        "radius", ATTR_DOMAIN_POINT, 0.005f);
+    const blender::IndexRange first_curve_points = curves.points_for_curve(0);
+    hair_rad_root = radii[first_curve_points.first()];
+    hair_rad_tip = radii[first_curve_points.last()];
+  }
+
   DRW_shgroup_uniform_texture(shgrp, "hairPointBuffer", curves_cache->final[subdiv].proc_tex);
   if (curves_cache->length_tex) {
     DRW_shgroup_uniform_texture(shgrp, "hairLen", curves_cache->length_tex);