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ProjectionUtils ​

Functions ​

Name
std::array< glm::mat4, 2 >constructZFlippedProjection(const glm::mat4 & m, bool flipX)
std::array< float, 6 >decomposePerspective(const glm::mat4 & m)<br>Decomposes the standard OpenGL perspective projection matrix into 6 frustum parameters.
std::array< glm::mat4, 5 >decomposePerspectiveBrown(const glm::mat4 & m)<br>Decomposition of an OpenGL perspective matrix into 4 submatrices described by Wayne Brown at https://learnwebgl.brown37.net/08_projections/projections_perspective.html#the-perspective-calculation.
std::array< glm::mat4, 3 >decomposePerspectiveShirley(const glm::mat4 & m)<br>Decomposition of an OpenGL perspective matrix into 3 submatrices described in the book Fundamentals of computer graphics, chapter 7 pg.
glm::vec4divide(const glm::vec4 & v)
voidextractZNearZFar(const glm::mat4 & projection, float & zNear, float & zFar)
glm::mat4viewport(float x, float y, float width, float height, float n, float f)
glm::mat4viewportVulkan(float x, float y, float width, float height, float n, float f)

Functions Documentation ​

function constructZFlippedProjection ​

cpp
std::array< glm::mat4, 2 > constructZFlippedProjection(
    const glm::mat4 & m,
    bool flipX
)
std::array< glm::mat4, 2 > constructZFlippedProjection(
    const glm::mat4 & m,
    bool flipX
)

function decomposePerspective ​

cpp
std::array< float, 6 > decomposePerspective(
    const glm::mat4 & m
)
std::array< float, 6 > decomposePerspective(
    const glm::mat4 & m
)

Decomposes the standard OpenGL perspective projection matrix into 6 frustum parameters.

Parameters:

  • m The perspective matrix

Return: Returns array of L,R,B,T,N,F

m[0,0] = 2n/(R-L) m[1,1] = 2n/(T-B) m[2,0] = (R+L)/(R-L) m[2,1] = (T+B)/(T-B) m[2,2] = -(f+n)/(f-n) = A (-1 for infinity f) m[3,2] = -(2fn)/(f-n) = B (-2n for infinity f) m[2,3] = -1

function decomposePerspectiveBrown ​

cpp
std::array< glm::mat4, 5 > decomposePerspectiveBrown(
    const glm::mat4 & m
)
std::array< glm::mat4, 5 > decomposePerspectiveBrown(
    const glm::mat4 & m
)

Decomposition of an OpenGL perspective matrix into 4 submatrices described by Wayne Brown at https://learnwebgl.brown37.net/08_projections/projections_perspective.html#the-perspective-calculation.

function decomposePerspectiveShirley ​

cpp
std::array< glm::mat4, 3 > decomposePerspectiveShirley(
    const glm::mat4 & m
)
std::array< glm::mat4, 3 > decomposePerspectiveShirley(
    const glm::mat4 & m
)

Decomposition of an OpenGL perspective matrix into 3 submatrices described in the book Fundamentals of computer graphics, chapter 7 pg.

  1. (SHIRLEY, Peter; ASHIKHMIN, Michael; MARSCHNER, Steve.)

function divide ​

cpp
glm::vec4 divide(
    const glm::vec4 & v
)
glm::vec4 divide(
    const glm::vec4 & v
)

function extractZNearZFar ​

cpp
void extractZNearZFar(
    const glm::mat4 & projection,
    float & zNear,
    float & zFar
)
void extractZNearZFar(
    const glm::mat4 & projection,
    float & zNear,
    float & zFar
)

function viewport ​

cpp
glm::mat4 viewport(
    float x,
    float y,
    float width,
    float height,
    float n,
    float f
)
glm::mat4 viewport(
    float x,
    float y,
    float width,
    float height,
    float n,
    float f
)

function viewportVulkan ​

cpp
glm::mat4 viewportVulkan(
    float x,
    float y,
    float width,
    float height,
    float n,
    float f
)
glm::mat4 viewportVulkan(
    float x,
    float y,
    float width,
    float height,
    float n,
    float f
)

Updated on 2025-05-31 at 12:55:31 +0000