Initial implementation of point_within_cone()

Initial implementation of point_within_cone(), without affine
transformation of input to align cone on X axis

1 files changed, 31 insertions, 0 deletions

diff --git a/src/spatial.c b/src/spatial.c
index f031ceb..98728df 100644
--- a/src/spatial.c
+++ b/src/spatial.c
@@ -12,6 +12,37 @@ static inline float dist(xas_spatial_coord a, xas_spatial_coord b) {
               + powf(b.z - a.z, 2.0f), 0.5f);
 }
 
+static int point_within_cone(xas_spatial_coord coord,
+                             xas_spatial_cone cone) {
+    float radius;
+
+    /*
+     * XXX Perform an affine transformation of the point along with the cone,
+     * fixing the point of the cone at 0, 0, 0 with the open end facing to the
+     * right on the X axis
+     */
+
+    /*
+     * If the point is to the left of the cone point, then the point is not
+     * within the cone.
+     */
+    if (coord.x < cone.coord.x) {
+        return 0;
+    }
+
+    radius = tanf(cone.angle / 2.0f) * cone.coord.x;
+
+    /*
+     * If the given point is outside the cone radius at its X coordinate, then
+     * it is outside of the cone.
+     */
+    if (fabs(coord.y) < radius || fabs(coord.z) < radius) {
+        return 0;
+    }
+
+    return 1;
+}
+
 static int buffer_realloc(xas_spatial_scene *scene,
                           xas_spatial_buffer *buffer) {
     float seconds = scene->radius / scene->speed;