Weight Paint: 'Sample' now supports multi-paint

Since the coloring uses sum or average of the weights of all selected
groups, the weight pick tool should also use that instead of reading
the weight of the single active group that you can't see.

1 files changed, 34 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/deform.c b/source/blender/blenkernel/intern/deform.c
index b09a0e92edb..135bf3e02ac 100644
--- a/source/blender/blenkernel/intern/deform.c
+++ b/source/blender/blenkernel/intern/deform.c
@@ -919,6 +919,40 @@ bool defvert_is_weight_zero(const struct MDeformVert *dvert, const int defgroup_
 	return true;
 }
 
+
+/**
+ * \return The representative weight of a multipaint group, used for
+ * viewport colors and actual painting.
+ *
+ * Result equal to sum of weights with auto normalize, and average otherwise.
+ * Value is not clamped, since painting relies on multiplication being always
+ * commutative with the collective weight function.
+ */
+float BKE_defvert_multipaint_collective_weight(
+        const struct MDeformVert *dv, int defbase_tot,
+        const bool *defbase_sel, int defbase_tot_sel, bool do_autonormalize)
+{
+	int i;
+	float total = 0.0f;
+	const MDeformWeight *dw = dv->dw;
+
+	for (i = dv->totweight; i != 0; i--, dw++) {
+		/* in multipaint, get the average if auto normalize is inactive
+		 * get the sum if it is active */
+		if (dw->def_nr < defbase_tot) {
+			if (defbase_sel[dw->def_nr]) {
+				total += dw->weight;
+			}
+		}
+	}
+
+	if (do_autonormalize == false) {
+		total /= defbase_tot_sel;
+	}
+
+	return total;
+}
+
 /* -------------------------------------------------------------------- */
 /* Defvert Array functions */