Frustum¶
#include <Imath/ImathFrustum.h>
The Frustum class template represents a 3D viewing frustum, with
predefined typedefs of type float and double.
Example:
#include <Imath/ImathFrustum.h>
#include <cassert>
void
frustum_example ()
{
float near = 1.7f;
float far = 567.0f;
float left = -3.5f;
float right = 2.0f;
float top = 0.9f;
float bottom = -1.3f;
Imath::Frustumf frustum (near, far, left, right, top, bottom, false);
Imath::M44f m = frustum.projectionMatrix ();
Imath::V3f p (1.0f, 1.0f, 1.0f);
Imath::V2f s = frustum.projectPointToScreen (p);
assert (s.equalWithAbsError (Imath::V2f (-0.345455f, -1.36364f), 0.0001f));
}
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template<class T>
class Frustum¶ Template class
Frustum<T>The frustum is always located with the eye point at the origin facing down -Z. This makes the Frustum class compatable with OpenGL (or anything that assumes a camera looks down -Z, hence with a right-handed coordinate system) but not with RenderMan which assumes the camera looks down +Z. Additional functions are provided for conversion from and from various camera coordinate spaces.
nearPlane/farPlane: near/far are keywords used by Microsoft’s compiler, so we use nearPlane/farPlane instead to avoid issues.
Constructors and Assignment
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inline constexpr Frustum() noexcept¶
Initialize with default values: near=0.1, far=1000.0, left=-1.0, right=1.0, top=1.0, bottom=-1.0, ortho=false.
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inline constexpr Frustum(T nearPlane, T farPlane, T left, T right, T top, T bottom, bool ortho = false) noexcept¶
Initialize to specific values.
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inline constexpr Frustum(T nearPlane, T farPlane, T fovx, T fovy, T aspect) noexcept¶
Initialize with fov and aspect.
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virtual ~Frustum() noexcept¶
Destructor.
Comparison
Query
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inline constexpr bool orthographic() const noexcept¶
Return true if the frustum is orthographic, false if perspective.
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inline constexpr T aspectExc() const¶
Return the aspect ratio.
Throw an exception if the aspect ratio is undefined.
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inline constexpr Matrix44<T> projectionMatrix() const noexcept¶
Return the project matrix that the frustum defines.
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inline constexpr Matrix44<T> projectionMatrixExc() const¶
Return the project matrix that the frustum defines.
Throw an exception if the frustum is degenerate.
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inline constexpr bool degenerate() const noexcept¶
Return true if the frustum is degenerate.
Set Value
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inline void set(T nearPlane, T farPlane, T left, T right, T top, T bottom, bool ortho = false) noexcept¶
Set functions change the entire state of the Frustum.
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inline void set(T nearPlane, T farPlane, T fovx, T fovy, T aspect) noexcept¶
Set functions change the entire state of the Frustum using field of view and aspect ratio.
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inline void setExc(T nearPlane, T farPlane, T fovx, T fovy, T aspect)¶
Set functions change the entire state of the Frustum using field of view and aspect ratio.
Throw an exception if
fovxand/orfovyare invalid.
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inline void modifyNearAndFar(T nearPlane, T farPlane) noexcept¶
Set the near and far clipping planes.
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inline void setOrthographic(bool) noexcept¶
Set the ortographic state.
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void planes(Plane3<T> p[6]) const noexcept¶
Set the planes in p to be the six bounding planes of the frustum, in the following order: top, right, bottom, left, near, far.
Note that the planes have normals that point out of the frustum.
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void planes(Plane3<T> p[6], const Matrix44<T> &M) const noexcept¶
Set the planes in p to be the six bounding planes of the frustum, in the following order: top, right, bottom, left, near, far.
Note that the planes have normals that point out of the frustum. Apply the given matrix to transform the frustum before setting the planes.
Utility Methods
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inline constexpr Line3<T> projectScreenToRay(const Vec2<T>&) const noexcept¶
Project a point in screen spaced to 3d ray.
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constexpr Vec2<T> projectPointToScreen(const Vec3<T>&) const noexcept¶
Project a 3D point into screen coordinates.
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constexpr Vec2<T> projectPointToScreenExc(const Vec3<T>&) const¶
Project a 3D point into screen coordinates.
Throw an exception if the point cannot be projected.
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constexpr T ZToDepth(long zval, long min, long max) const noexcept¶
Map a z value to its depth in the frustum.
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constexpr T ZToDepthExc(long zval, long min, long max) const¶
Map a z value to its depth in the frustum.
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constexpr T normalizedZToDepth(T zval) const noexcept¶
Map a normalized z value to its depth in the frustum.
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constexpr T normalizedZToDepthExc(T zval) const¶
Map a normalized z value to its depth in the frustum.
Throw an exception on error.
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constexpr long DepthToZExc(T depth, long zmin, long zmax) const¶
Map depth to z value. Throw an exception on error.
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inline constexpr Frustum() noexcept¶
