1 files changed, 16 insertions, 0 deletions
diff --git a/balls.h b/balls.h
index 051c185..a767db0 100644
--- a/balls.h
+++ b/balls.h
@@ -4,6 +4,22 @@ typedef struct {
 	float2 min, max;
 } Rectangle;
 
+/*
+ * A partition of the set of all possible collisions between pairs of balls.
+ * Collisions within a cell of the partition can run concurrently.  Cells must
+ * run sequentially.
+*/
+typedef struct {
+	struct cell {
+		size_t (*ballIndices)[2]; /* Array of pairs of ball indices. */
+		size_t size; /* Length of ballIndices. */
+	} *cells; /* Array of cells. */
+	size_t size; /* Length of cell array. */
+} Partition;
+
+Partition partitionCollisions(size_t nBalls);
+void freePartition(Partition part);
+
 int isCollision(float2 p1, float r1, float2 p2, float r2);
 Rectangle insetRect(Rectangle r, float n);