From eaf45e489d94d19678d56554d3fec6ed0ded1c31 Mon Sep 17 00:00:00 2001
From: Recep Aslantas <info@recp.me>
Date: Sun, 31 Dec 2017 17:17:39 +0300
Subject: [PATCH] view frustum center

---
 include/cglm/call/cam.h |  4 ++++
 include/cglm/cam.h      | 23 +++++++++++++++++++++++
 src/cam.c               |  6 ++++++
 3 files changed, 33 insertions(+)

diff --git a/include/cglm/call/cam.h b/include/cglm/call/cam.h
index 2a7d661..7b2c409 100644
--- a/include/cglm/call/cam.h
+++ b/include/cglm/call/cam.h
@@ -56,6 +56,10 @@ CGLM_EXPORT
 void
 glmc_frustum_corners(mat4 invMat, vec4 dest[8]);
 
+CGLM_EXPORT
+void
+glmc_frustum_center(vec4 corners[8], vec4 dest);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/cglm/cam.h b/include/cglm/cam.h
index 41a2c4b..e8c4afb 100644
--- a/include/cglm/cam.h
+++ b/include/cglm/cam.h
@@ -503,4 +503,27 @@ glm_frustum_corners(mat4 invMat, vec4 dest[8]) {
   glm_vec4_scale(dest[7], 1.0f / dest[7][3], dest[7]);
 }
 
+/*!
+ * @brief finds center of view frustum
+ *
+ * @param[in]  corners view frustum corners
+ * @param[out] dest    view frustum center
+ */
+CGLM_INLINE
+void
+glm_frustum_center(vec4 corners[8], vec4 dest) {
+  glm_vec4_broadcast(0.0f, dest);
+
+  glm_vec4_add(corners[0], dest, dest);
+  glm_vec4_add(corners[1], dest, dest);
+  glm_vec4_add(corners[2], dest, dest);
+  glm_vec4_add(corners[3], dest, dest);
+  glm_vec4_add(corners[4], dest, dest);
+  glm_vec4_add(corners[5], dest, dest);
+  glm_vec4_add(corners[6], dest, dest);
+  glm_vec4_add(corners[7], dest, dest);
+
+  glm_vec4_scale(dest, 0.125f, dest);
+}
+
 #endif /* cglm_vcam_h */
diff --git a/src/cam.c b/src/cam.c
index f588619..602b1fc 100644
--- a/src/cam.c
+++ b/src/cam.c
@@ -78,3 +78,9 @@ void
 glmc_frustum_corners(mat4 invMat, vec4 dest[8]) {
   glm_frustum_corners(invMat, dest);
 }
+
+CGLM_EXPORT
+void
+glmc_frustum_center(vec4 corners[8], vec4 dest) {
+  glm_frustum_center(corners, dest);
+}