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+/**********************************************************************************************
+*
+* raylibExtras * Utilities and Shared Components for Raylib
+*
+* RLAssets * Simple Asset Managment System for Raylib
+*
+* LICENSE: MIT
+*
+* Copyright (c) 2020 Jeffery Myers
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to deal
+* in the Software without restriction, including without limitation the rights
+* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+* copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all
+* copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+* SOFTWARE.
+*
+**********************************************************************************************/
+
+
+#include "frustum.h"
+#include "rlgl.h"
+#include "raymath.h"
+
+#include <math.h>
+#include <stddef.h>
+
+void NormalizePlane(Vector4* plane)
+{
+ if (plane == NULL)
+ return;
+
+ float magnitude = sqrtf(plane->x * plane->x + plane->y * plane->y + plane->z * plane->z);
+
+ plane->x /= magnitude;
+ plane->y /= magnitude;
+ plane->z /= magnitude;
+ plane->w /= magnitude;
+}
+
+// void ExtractFrustum(Frustum* frustum)
+void ExtractFrustum(Frustum* frustum, Matrix projection, Matrix modelview)
+{
+ if (frustum == NULL)
+ return;
+
+ // Matrix projection = rlGetMatrixProjection();
+ // Matrix modelview = rlGetMatrixModelview();
+
+ Matrix planes = { 0 };
+
+ planes.m0 = modelview.m0 * projection.m0 + modelview.m1 * projection.m4 + modelview.m2 * projection.m8 + modelview.m3 * projection.m12;
+ planes.m1 = modelview.m0 * projection.m1 + modelview.m1 * projection.m5 + modelview.m2 * projection.m9 + modelview.m3 * projection.m13;
+ planes.m2 = modelview.m0 * projection.m2 + modelview.m1 * projection.m6 + modelview.m2 * projection.m10 + modelview.m3 * projection.m14;
+ planes.m3 = modelview.m0 * projection.m3 + modelview.m1 * projection.m7 + modelview.m2 * projection.m11 + modelview.m3 * projection.m15;
+ planes.m4 = modelview.m4 * projection.m0 + modelview.m5 * projection.m4 + modelview.m6 * projection.m8 + modelview.m7 * projection.m12;
+ planes.m5 = modelview.m4 * projection.m1 + modelview.m5 * projection.m5 + modelview.m6 * projection.m9 + modelview.m7 * projection.m13;
+ planes.m6 = modelview.m4 * projection.m2 + modelview.m5 * projection.m6 + modelview.m6 * projection.m10 + modelview.m7 * projection.m14;
+ planes.m7 = modelview.m4 * projection.m3 + modelview.m5 * projection.m7 + modelview.m6 * projection.m11 + modelview.m7 * projection.m15;
+ planes.m8 = modelview.m8 * projection.m0 + modelview.m9 * projection.m4 + modelview.m10 * projection.m8 + modelview.m11 * projection.m12;
+ planes.m9 = modelview.m8 * projection.m1 + modelview.m9 * projection.m5 + modelview.m10 * projection.m9 + modelview.m11 * projection.m13;
+ planes.m10 = modelview.m8 * projection.m2 + modelview.m9 * projection.m6 + modelview.m10 * projection.m10 + modelview.m11 * projection.m14;
+ planes.m11 = modelview.m8 * projection.m3 + modelview.m9 * projection.m7 + modelview.m10 * projection.m11 + modelview.m11 * projection.m15;
+ planes.m12 = modelview.m12 * projection.m0 + modelview.m13 * projection.m4 + modelview.m14 * projection.m8 + modelview.m15 * projection.m12;
+ planes.m13 = modelview.m12 * projection.m1 + modelview.m13 * projection.m5 + modelview.m14 * projection.m9 + modelview.m15 * projection.m13;
+ planes.m14 = modelview.m12 * projection.m2 + modelview.m13 * projection.m6 + modelview.m14 * projection.m10 + modelview.m15 * projection.m14;
+ planes.m15 = modelview.m12 * projection.m3 + modelview.m13 * projection.m7 + modelview.m14 * projection.m11 + modelview.m15 * projection.m15;
+
+ frustum->Planes[Right] = (Vector4){ planes.m3 - planes.m0, planes.m7 - planes.m4, planes.m11 - planes.m8, planes.m15 - planes.m12 };
+ NormalizePlane(&frustum->Planes[Right]);
+
+ frustum->Planes[Left] = (Vector4){ planes.m3 + planes.m0, planes.m7 + planes.m4, planes.m11 + planes.m8, planes.m15 + planes.m12 };
+ NormalizePlane(&frustum->Planes[Left]);
+
+ frustum->Planes[Top] = (Vector4){ planes.m3 - planes.m1, planes.m7 - planes.m5, planes.m11 - planes.m9, planes.m15 - planes.m13 };
+ NormalizePlane(&frustum->Planes[Top]);
+
+ frustum->Planes[Bottom] = (Vector4){ planes.m3 + planes.m1, planes.m7 + planes.m5, planes.m11 + planes.m9, planes.m15 + planes.m13 };
+ NormalizePlane(&frustum->Planes[Bottom]);
+
+ frustum->Planes[Back] = (Vector4){ planes.m3 - planes.m2, planes.m7 - planes.m6, planes.m11 - planes.m10, planes.m15 - planes.m14 };
+ NormalizePlane(&frustum->Planes[Back]);
+
+ frustum->Planes[Front] = (Vector4){ planes.m3 + planes.m2, planes.m7 + planes.m6, planes.m11 + planes.m10, planes.m15 + planes.m14 };
+ NormalizePlane(&frustum->Planes[Front]);
+}
+
+float DistanceToPlaneV(const Vector4* plane, const Vector3* position)
+{
+ return (plane->x * position->x + plane->y * position->y + plane->z * position->z + plane->w);
+}
+
+float DistanceToPlane(const Vector4* plane, float x, float y, float z)
+{
+ return (plane->x * x + plane->y * y + plane->z * z + plane->w);
+}
+
+bool PointInFrustumV(Frustum* frustum, Vector3 position)
+{
+ if (frustum == NULL)
+ return false;
+
+ for (int i = 0; i < 6; i++)
+ {
+ if (DistanceToPlaneV(&frustum->Planes[i], &position) <= 0) // point is behind plane
+ return false;
+ }
+
+ return true;
+}
+
+bool PointInFrustum(Frustum* frustum, float x, float y, float z)
+{
+ if (frustum == NULL)
+ return false;
+
+ for (int i = 0; i < 6; i++)
+ {
+ if (DistanceToPlane(&frustum->Planes[i], x, y, z) <= 0) // point is behind plane
+ return false;
+ }
+
+ return true;
+}
+
+bool SphereInFrustumV(Frustum* frustum, Vector3 position, float radius)
+{
+ if (frustum == NULL)
+ return false;
+
+ for (int i = 0; i < 6; i++)
+ {
+ if (DistanceToPlaneV(&frustum->Planes[i], &position) < -radius) // center is behind plane by more than the radius
+ return false;
+ }
+
+ return true;
+}
+bool AABBoxInFrustum(Frustum* frustum, Vector3 min, Vector3 max)
+{
+ // if any point is in and we are good
+ if (PointInFrustum(frustum, min.x, min.y, min.z))
+ return true;
+
+ if (PointInFrustum(frustum, min.x, max.y, min.z))
+ return true;
+
+ if (PointInFrustum(frustum, max.x, max.y, min.z))
+ return true;
+
+ if (PointInFrustum(frustum, max.x, min.y, min.z))
+ return true;
+
+ if (PointInFrustum(frustum, min.x, min.y, max.z))
+ return true;
+
+ if (PointInFrustum(frustum, min.x, max.y, max.z))
+ return true;
+
+ if (PointInFrustum(frustum, max.x, max.y, max.z))
+ return true;
+
+ if (PointInFrustum(frustum, max.x, min.y, max.z))
+ return true;
+
+ // check to see if all points are outside of any one plane, if so the entire box is outside
+ for (int i = 0; i < 6; i++)
+ {
+ bool oneInside = false;
+
+ if (DistanceToPlane(&frustum->Planes[i], min.x, min.y, min.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], max.x, min.y, min.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], max.x, max.y, min.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], min.x, max.y, min.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], min.x, min.y, max.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], max.x, min.y, max.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], max.x, max.y, max.z) >= 0)
+ oneInside = true;
+
+ if (DistanceToPlane(&frustum->Planes[i], min.x, max.y, max.z) >= 0)
+ oneInside = true;
+
+ if (!oneInside)
+ return false;
+ }
+
+ // the box extends outside the frustum but crosses it
+ return true;
+}