SLFrustum Class Reference

Matrix to 6 frustum plane conversion functions. More...

#include <SLFrustum.h>

Static Public Member Functions
static void	viewToFrustumPlanes (SLPlane *planes, const SLMat4f &projectionMat, const SLMat4f &viewMat)
static void	viewToFrustumPlanes (SLPlane *planes, const SLMat4f &A)
static void	getPointsInViewSpace (SLVec3f *points, float fovV, float ratio, float clipNear, float clipFar)
	Returns frustum points in view space. More...

Detailed Description

Matrix to 6 frustum plane conversion functions.

Definition at line 15 of file SLFrustum.h.

Member Function Documentation

getPointsInViewSpace()

void SLFrustum::getPointsInViewSpace ( SLVec3f *  points, float  fovV, float  ratio, float  clipNear, float  clipFar  )

static

Returns frustum points in view space.

Definition at line 73 of file SLFrustum.cpp.

{
    SLfloat tanFovV = tan(Utils::DEG2RAD * fovV * 0.5f);
 
    // Calculate the 4 points on the near plane
    SLfloat t = tanFovV * clipNear; // top
    SLfloat b = -t;                 // bottom
    SLfloat r = ratio * t;          // right
    SLfloat l = -r;                 // left
    points[0] = (SLVec3f(r, t, -clipNear));
    points[1] = (SLVec3f(r, b, -clipNear));
    points[2] = (SLVec3f(l, t, -clipNear));
    points[3] = (SLVec3f(l, b, -clipNear));
 
    // Calculate the 4 points on the far plane
    t = tanFovV * clipFar; // top
    b = -t;                // bottom
    r = ratio * t;         // right
    l = -r;                // left
 
    points[4] = (SLVec3f(r, t, -clipFar));
    points[5] = (SLVec3f(r, b, -clipFar));
    points[6] = (SLVec3f(l, t, -clipFar));
    points[7] = (SLVec3f(l, b, -clipFar));
}

viewToFrustumPlanes() [1/2]

void SLFrustum::viewToFrustumPlanes ( SLPlane *  planes, const SLMat4f &  A  )

static

Calculates the coefficients of the 6 frustum planes from the passed matrix A. See the paper from Gribb and Hartmann: https://www.gamedevs.org/uploads/fast-extraction-viewing-frustum-planes-from-world-view-projection-matrix.pdf

Parameters

planes	Pointer to an array of 6 SLPlanes (L R T B N F)
A	The projection matrix

Definition at line 42 of file SLFrustum.cpp.

{
    // set the A,B,C & D coefficient for each plane
    // Order is L R T B N F
    planes[0].setCoefficients(A.m(0) + A.m(3),
                              A.m(4) + A.m(7),
                              A.m(8) + A.m(11),
                              A.m(12) + A.m(15));
    planes[1].setCoefficients(-A.m(0) + A.m(3),
                              -A.m(4) + A.m(7),
                              -A.m(8) + A.m(11),
                              -A.m(12) + A.m(15));
    planes[2].setCoefficients(-A.m(1) + A.m(3),
                              -A.m(5) + A.m(7),
                              -A.m(9) + A.m(11),
                              -A.m(13) + A.m(15));
    planes[3].setCoefficients(A.m(1) + A.m(3),
                              A.m(5) + A.m(7),
                              A.m(9) + A.m(11),
                              A.m(13) + A.m(15));
    planes[4].setCoefficients(A.m(2) + A.m(3),
                              A.m(6) + A.m(7),
                              A.m(10) + A.m(11),
                              A.m(14) + A.m(15));
    planes[5].setCoefficients(-A.m(2) + A.m(3),
                              -A.m(6) + A.m(7),
                              -A.m(10) + A.m(11),
                              -A.m(14) + A.m(15));
}

viewToFrustumPlanes() [2/2]

void SLFrustum::viewToFrustumPlanes ( SLPlane *  planes, const SLMat4f &  projectionMat, const SLMat4f &  viewMat  )

static

Calculates the coefficients of the 6 frustum planes from the passed projection and view matrices. See the paper from Gribb and Hartmann: https://www.gamedevs.org/uploads/fast-extraction-viewing-frustum-planes-from-world-view-projection-matrix.pdf

Parameters

planes	Pointer to an array of 6 SLPlanes (L R T B N F)
projectionMat	4x4 projection matrix
viewMat	4x4 view matrix

Definition at line 24 of file SLFrustum.cpp.

{
    // Combine view and projection matrix
    SLMat4f A = projectionMat * viewMat;
 
    // Order is L R T B N F
    viewToFrustumPlanes(planes, A);
}

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The documentation for this class was generated from the following files:

• SLFrustum.h
• SLFrustum.cpp