Frustum culling should be working.

2016-02-09 17:12:23 +01:00
parent b9d6d59c62
commit 239a8e7a6a
5 changed files with 93 additions and 148 deletions
@@ -0,0 +1,77 @@
+#ifndef Frustum_h__
+#define Frustum_h__
+
+#include "../GLM.h"
+#include "AABB.h"
+#include <bitset>
+
+//A frustum defined by 6 planes.
+struct Frustum
+{
+    //Contains points P in: dot(normal, P) + d = 0
+    struct Plane
+    {
+        glm::vec3 Normal;
+        float Distance;
+    };
+
+    enum class Output
+    {
+        Inside,
+        Outside,
+        Intersects
+    };
+    Plane Planes[6];
+
+    Frustum() = default;
+    Frustum(glm::mat4x4 viewProjMatrix)
+    {
+        //Order: Right, left, top, bottom, far, near.
+        int sign = 1;
+        for (int i = 0; i < 6; ++i) {
+            sign = -sign;
+            int index = i / 2;
+            Plane& plane = Planes[i];
+            plane.Normal.x = viewProjMatrix[0].w + sign * viewProjMatrix[0][index];
+            plane.Normal.y = viewProjMatrix[1].w + sign * viewProjMatrix[1][index];
+            plane.Normal.z = viewProjMatrix[2].w + sign * viewProjMatrix[2][index];
+            plane.Distance = viewProjMatrix[3].w + sign * viewProjMatrix[3][index];
+            float divByNormalLength = 1.0f / glm::length(plane.Normal);
+            plane.Normal *= divByNormalLength;
+            plane.Distance *= divByNormalLength;
+        }
+    }
+
+    Output VsAABB(const AABB& box) const
+    {
+        const glm::vec3& maxCorner = box.MaxCorner();
+        const glm::vec3& minCorner = box.MinCorner();
+        bool completelyInside = true;
+        for (const Plane& p : Planes) {
+            bool anyWasInside = false;
+            bool anyWasOutside = false;
+            //If points are on both sides of the plane, we can stop.
+            for (int i = 0; i < 8 && (!anyWasInside || !anyWasOutside); ++i) {
+                std::bitset<3> bits(i);
+                glm::vec3 corner;
+                corner.x = bits.test(0) ? maxCorner.x : minCorner.x;
+                corner.y = bits.test(1) ? maxCorner.y : minCorner.y;
+                corner.z = bits.test(2) ? maxCorner.z : minCorner.z;
+                if (glm::dot(p.Normal, corner) > -p.Distance) {
+                    anyWasInside = true;
+                } else {
+                    anyWasOutside = true;
+                }
+            }
+            if (!anyWasInside) {
+                return Output::Outside;
+            }
+            if (anyWasOutside) {
+                completelyInside = false;
+            }
+        }
+        return completelyInside ? Output::Inside : Output::Intersects;
+    }
+};
+
+#endif