1 files changed, 48 insertions, 0 deletions
diff --git a/libs/cglm/include/cglm/clipspace/persp.h b/libs/cglm/include/cglm/clipspace/persp.h
new file mode 100644
index 0000000..15aa715
--- /dev/null
+++ b/libs/cglm/include/cglm/clipspace/persp.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c), Recep Aslantas.
+ *
+ * MIT License (MIT), http://opensource.org/licenses/MIT
+ * Full license can be found in the LICENSE file
+ */
+
+/*
+ Functions:
+   CGLM_INLINE void  glm_persp_decomp_far(mat4 proj, float *farZ)
+   CGLM_INLINE float glm_persp_fovy(mat4 proj)
+   CGLM_INLINE float glm_persp_aspect(mat4 proj)
+   CGLM_INLINE void  glm_persp_sizes(mat4 proj, float fovy, vec4 dest)
+ */
+
+#ifndef cglm_persp_h
+#define cglm_persp_h
+
+#include "../common.h"
+#include "../plane.h"
+#include "../mat4.h"
+
+/*!
+ * @brief returns field of view angle along the Y-axis (in radians)
+ *
+ * if you need to degrees, use glm_deg to convert it or use this:
+ * fovy_deg = glm_deg(glm_persp_fovy(projMatrix))
+ *
+ * @param[in] proj perspective projection matrix
+ */
+CGLM_INLINE
+float
+glm_persp_fovy(mat4 proj) {
+  return 2.0f * atanf(1.0f / proj[1][1]);
+}
+
+/*!
+ * @brief returns aspect ratio of perspective projection
+ *
+ * @param[in] proj perspective projection matrix
+ */
+CGLM_INLINE
+float
+glm_persp_aspect(mat4 proj) {
+  return proj[1][1] / proj[0][0];
+}
+
+#endif /* cglm_persp_h */