55 lines
2.4 KiB
C++
55 lines
2.4 KiB
C++
//
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// Created by dawsh on 1/25/24.
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//
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#pragma once
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#include "Plane.h"
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namespace Geometry
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{
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enum class FrustumType
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{
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Invalid,
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/// Set the Frustum type to this value to define the orthographic projection formula. In orthographic projection,
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/// 3D images are projected onto a 2D plane essentially by flattening the object along one direction (the plane normal).
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/// The size of the projected images appear the same independent of their distance to the camera, and distant objects will
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/// not appear smaller. The shape of the Frustum is identical to an oriented bounding box (OBB).
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Orthographic,
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/// Set the Frustum type to this value to use the perspective projection formula. With perspective projection, the 2D
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/// image is formed by projecting 3D points towards a single point (the eye point/tip) of the Frustum, and computing the
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/// point of intersection of the line of the projection and the near plane of the Frustum.
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/// This corresponds to the optics in the real-world, and objects become smaller as they move to the distance.
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/// The shape of the Frustum is a rectangular pyramid capped from the tip.
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Perspective
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};
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class Frustum {
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public:
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Plane TopFace;
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Plane BottomFace;
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Plane RightFace;
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Plane LeftFace;
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Plane FarFace;
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Plane NearFace;
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static Frustum CreateFrustumFromCamera(const Camera& cam, float aspect, float fovY, float zNear, float zFar);
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};
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Frustum Frustum::CreateFrustumFromCamera(const Camera &cam, float aspect, float fovY, float zNear, float zFar) {
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Frustum frustum;
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const float halfVSide = zFar * tanf(fovY * 0.5f);
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const float halfHSide = halfVSide * aspect;
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const Vector3 frontMultFar = cam.Front * zFar;
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frustum.NearFace = Plane{cam.Position + cam.Front * zNear, cam.Front};
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frustum.FarFace = Plane{cam.Position + frontMultFar, -cam.Front};
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frustum.RightFace = Plane{cam.Position, Vector3::Cross(frontMultFar - cam.Right * halfHSide, cam.Up)};
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frustum.LeftFace = Plane{cam.Position, Vector3::Cross(cam.Up, frontMultFar+cam.Right*halfHSide)};
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frustum.TopFace = Plane{cam.Position, Vector3::Cross(cam.Right, frontMultFar - cam.Up * halfVSide)};
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frustum.BottomFace = Plane{cam.Position, Vector3::Cross(frontMultFar + cam.Up * halfVSide, cam.Right)};
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return frustum;
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}
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} |