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gecko-dev/gfx/thebes/gfx3DMatrix.cpp

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gfxMatrix.h"
#include "gfx3DMatrix.h"
#include "gfx2DGlue.h"
#include "mozilla/gfx/Tools.h"
#include <math.h>
#include <algorithm>
using namespace std;
using namespace mozilla;
using namespace mozilla::gfx;
/* Force small values to zero. We do this to avoid having sin(360deg)
* evaluate to a tiny but nonzero value.
*/
static double FlushToZero(double aVal)
{
if (-FLT_EPSILON < aVal && aVal < FLT_EPSILON)
return 0.0f;
else
return aVal;
}
/* Computes tan(aTheta). For values of aTheta such that tan(aTheta) is
* undefined or very large, SafeTangent returns a manageably large value
* of the correct sign.
*/
static double SafeTangent(double aTheta)
{
const double kEpsilon = 0.0001;
/* tan(theta) = sin(theta)/cos(theta); problems arise when
* cos(theta) is too close to zero. Limit cos(theta) to the
* range [-1, -epsilon] U [epsilon, 1].
*/
double sinTheta = sin(aTheta);
double cosTheta = cos(aTheta);
if (cosTheta >= 0 && cosTheta < kEpsilon)
cosTheta = kEpsilon;
else if (cosTheta < 0 && cosTheta >= -kEpsilon)
cosTheta = -kEpsilon;
return FlushToZero(sinTheta / cosTheta);
}
gfx3DMatrix::gfx3DMatrix(void)
{
_11 = _22 = _33 = _44 = 1.0f;
_12 = _13 = _14 = 0.0f;
_21 = _23 = _24 = 0.0f;
_31 = _32 = _34 = 0.0f;
_41 = _42 = _43 = 0.0f;
}
gfx3DMatrix
gfx3DMatrix::operator*(const gfx3DMatrix &aMatrix) const
{
if (Is2D() && aMatrix.Is2D()) {
return Multiply2D(aMatrix);
}
gfx3DMatrix matrix;
matrix._11 = _11 * aMatrix._11 + _12 * aMatrix._21 + _13 * aMatrix._31 + _14 * aMatrix._41;
matrix._21 = _21 * aMatrix._11 + _22 * aMatrix._21 + _23 * aMatrix._31 + _24 * aMatrix._41;
matrix._31 = _31 * aMatrix._11 + _32 * aMatrix._21 + _33 * aMatrix._31 + _34 * aMatrix._41;
matrix._41 = _41 * aMatrix._11 + _42 * aMatrix._21 + _43 * aMatrix._31 + _44 * aMatrix._41;
matrix._12 = _11 * aMatrix._12 + _12 * aMatrix._22 + _13 * aMatrix._32 + _14 * aMatrix._42;
matrix._22 = _21 * aMatrix._12 + _22 * aMatrix._22 + _23 * aMatrix._32 + _24 * aMatrix._42;
matrix._32 = _31 * aMatrix._12 + _32 * aMatrix._22 + _33 * aMatrix._32 + _34 * aMatrix._42;
matrix._42 = _41 * aMatrix._12 + _42 * aMatrix._22 + _43 * aMatrix._32 + _44 * aMatrix._42;
matrix._13 = _11 * aMatrix._13 + _12 * aMatrix._23 + _13 * aMatrix._33 + _14 * aMatrix._43;
matrix._23 = _21 * aMatrix._13 + _22 * aMatrix._23 + _23 * aMatrix._33 + _24 * aMatrix._43;
matrix._33 = _31 * aMatrix._13 + _32 * aMatrix._23 + _33 * aMatrix._33 + _34 * aMatrix._43;
matrix._43 = _41 * aMatrix._13 + _42 * aMatrix._23 + _43 * aMatrix._33 + _44 * aMatrix._43;
matrix._14 = _11 * aMatrix._14 + _12 * aMatrix._24 + _13 * aMatrix._34 + _14 * aMatrix._44;
matrix._24 = _21 * aMatrix._14 + _22 * aMatrix._24 + _23 * aMatrix._34 + _24 * aMatrix._44;
matrix._34 = _31 * aMatrix._14 + _32 * aMatrix._24 + _33 * aMatrix._34 + _34 * aMatrix._44;
matrix._44 = _41 * aMatrix._14 + _42 * aMatrix._24 + _43 * aMatrix._34 + _44 * aMatrix._44;
return matrix;
}
gfx3DMatrix&
gfx3DMatrix::operator*=(const gfx3DMatrix &aMatrix)
{
return *this = *this * aMatrix;
}
gfx3DMatrix
gfx3DMatrix::Multiply2D(const gfx3DMatrix &aMatrix) const
{
gfx3DMatrix matrix;
matrix._11 = _11 * aMatrix._11 + _12 * aMatrix._21;
matrix._21 = _21 * aMatrix._11 + _22 * aMatrix._21;
matrix._41 = _41 * aMatrix._11 + _42 * aMatrix._21 + aMatrix._41;
matrix._12 = _11 * aMatrix._12 + _12 * aMatrix._22;
matrix._22 = _21 * aMatrix._12 + _22 * aMatrix._22;
matrix._42 = _41 * aMatrix._12 + _42 * aMatrix._22 + aMatrix._42;
return matrix;
}
bool
gfx3DMatrix::operator==(const gfx3DMatrix& o) const
{
// XXX would be nice to memcmp here, but that breaks IEEE 754 semantics
return _11 == o._11 && _12 == o._12 && _13 == o._13 && _14 == o._14 &&
_21 == o._21 && _22 == o._22 && _23 == o._23 && _24 == o._24 &&
_31 == o._31 && _32 == o._32 && _33 == o._33 && _34 == o._34 &&
_41 == o._41 && _42 == o._42 && _43 == o._43 && _44 == o._44;
}
bool
gfx3DMatrix::operator!=(const gfx3DMatrix& o) const
{
return !((*this) == o);
}
bool
gfx3DMatrix::FuzzyEqual(const gfx3DMatrix& o) const
{
static const float error = 1e-4;
return gfx::FuzzyEqual(_11, o._11, error) && gfx::FuzzyEqual(_12, o._12, error) &&
gfx::FuzzyEqual(_13, o._13, error) && gfx::FuzzyEqual(_14, o._14, error) &&
gfx::FuzzyEqual(_21, o._21, error) && gfx::FuzzyEqual(_22, o._22, error) &&
gfx::FuzzyEqual(_23, o._23, error) && gfx::FuzzyEqual(_24, o._24, error) &&
gfx::FuzzyEqual(_31, o._31, error) && gfx::FuzzyEqual(_32, o._32, error) &&
gfx::FuzzyEqual(_33, o._33, error) && gfx::FuzzyEqual(_34, o._34, error) &&
gfx::FuzzyEqual(_41, o._41, error) && gfx::FuzzyEqual(_42, o._42, error) &&
gfx::FuzzyEqual(_43, o._43, error) && gfx::FuzzyEqual(_44, o._44, error);
}
gfx3DMatrix&
gfx3DMatrix::operator/=(const gfxFloat scalar)
{
_11 /= scalar;
_12 /= scalar;
_13 /= scalar;
_14 /= scalar;
_21 /= scalar;
_22 /= scalar;
_23 /= scalar;
_24 /= scalar;
_31 /= scalar;
_32 /= scalar;
_33 /= scalar;
_34 /= scalar;
_41 /= scalar;
_42 /= scalar;
_43 /= scalar;
_44 /= scalar;
return *this;
}
gfx3DMatrix
gfx3DMatrix::From2D(const gfxMatrix &aMatrix)
{
gfx3DMatrix matrix;
matrix._11 = (float)aMatrix._11;
matrix._12 = (float)aMatrix._12;
matrix._21 = (float)aMatrix._21;
matrix._22 = (float)aMatrix._22;
matrix._41 = (float)aMatrix._31;
matrix._42 = (float)aMatrix._32;
return matrix;
}
bool
gfx3DMatrix::IsIdentity() const
{
return _11 == 1.0f && _12 == 0.0f && _13 == 0.0f && _14 == 0.0f &&
_21 == 0.0f && _22 == 1.0f && _23 == 0.0f && _24 == 0.0f &&
_31 == 0.0f && _32 == 0.0f && _33 == 1.0f && _34 == 0.0f &&
_41 == 0.0f && _42 == 0.0f && _43 == 0.0f && _44 == 1.0f;
}
void
gfx3DMatrix::Translate(const Point3D& aPoint)
{
_41 += aPoint.x * _11 + aPoint.y * _21 + aPoint.z * _31;
_42 += aPoint.x * _12 + aPoint.y * _22 + aPoint.z * _32;
_43 += aPoint.x * _13 + aPoint.y * _23 + aPoint.z * _33;
_44 += aPoint.x * _14 + aPoint.y * _24 + aPoint.z * _34;
}
void
gfx3DMatrix::TranslatePost(const Point3D& aPoint)
{
_11 += _14 * aPoint.x;
_21 += _24 * aPoint.x;
_31 += _34 * aPoint.x;
_41 += _44 * aPoint.x;
_12 += _14 * aPoint.y;
_22 += _24 * aPoint.y;
_32 += _34 * aPoint.y;
_42 += _44 * aPoint.y;
_13 += _14 * aPoint.z;
_23 += _24 * aPoint.z;
_33 += _34 * aPoint.z;
_43 += _44 * aPoint.z;
}
void
gfx3DMatrix::ScalePost(float aX, float aY, float aZ)
{
_11 *= aX;
_21 *= aX;
_31 *= aX;
_41 *= aX;
_12 *= aY;
_22 *= aY;
_32 *= aY;
_42 *= aY;
_13 *= aZ;
_23 *= aZ;
_33 *= aZ;
_43 *= aZ;
}
void
gfx3DMatrix::ChangeBasis(const Point3D& aOrigin)
{
// Translate to the origin before applying this matrix.
Translate(-aOrigin);
// Translate back into position after applying this matrix.
TranslatePost(aOrigin);
}
void
gfx3DMatrix::Scale(float aX, float aY, float aZ)
{
(*this)[0] *= aX;
(*this)[1] *= aY;
(*this)[2] *= aZ;
}
void
gfx3DMatrix::Perspective(float aDepth)
{
NS_ASSERTION(aDepth > 0.0f, "Perspective must be positive!");
_31 += -1.0/aDepth * _41;
_32 += -1.0/aDepth * _42;
_33 += -1.0/aDepth * _43;
_34 += -1.0/aDepth * _44;
}
void gfx3DMatrix::SkewXY(double aXSkew, double aYSkew)
{
float tanX = SafeTangent(aXSkew);
float tanY = SafeTangent(aYSkew);
float temp;
temp = _11;
_11 += tanY * _21;
_21 += tanX * temp;
temp = _12;
_12 += tanY * _22;
_22 += tanX * temp;
temp = _13;
_13 += tanY * _23;
_23 += tanX * temp;
temp = _14;
_14 += tanY * _24;
_24 += tanX * temp;
}
void
gfx3DMatrix::RotateX(double aTheta)
{
double cosTheta = FlushToZero(cos(aTheta));
double sinTheta = FlushToZero(sin(aTheta));
float temp;
temp = _21;
_21 = cosTheta * _21 + sinTheta * _31;
_31 = -sinTheta * temp + cosTheta * _31;
temp = _22;
_22 = cosTheta * _22 + sinTheta * _32;
_32 = -sinTheta * temp + cosTheta * _32;
temp = _23;
_23 = cosTheta * _23 + sinTheta * _33;
_33 = -sinTheta * temp + cosTheta * _33;
temp = _24;
_24 = cosTheta * _24 + sinTheta * _34;
_34 = -sinTheta * temp + cosTheta * _34;
}
void
gfx3DMatrix::RotateY(double aTheta)
{
double cosTheta = FlushToZero(cos(aTheta));
double sinTheta = FlushToZero(sin(aTheta));
float temp;
temp = _11;
_11 = cosTheta * _11 + -sinTheta * _31;
_31 = sinTheta * temp + cosTheta * _31;
temp = _12;
_12 = cosTheta * _12 + -sinTheta * _32;
_32 = sinTheta * temp + cosTheta * _32;
temp = _13;
_13 = cosTheta * _13 + -sinTheta * _33;
_33 = sinTheta * temp + cosTheta * _33;
temp = _14;
_14 = cosTheta * _14 + -sinTheta * _34;
_34 = sinTheta * temp + cosTheta * _34;
}
void
gfx3DMatrix::RotateZ(double aTheta)
{
double cosTheta = FlushToZero(cos(aTheta));
double sinTheta = FlushToZero(sin(aTheta));
float temp;
temp = _11;
_11 = cosTheta * _11 + sinTheta * _21;
_21 = -sinTheta * temp + cosTheta * _21;
temp = _12;
_12 = cosTheta * _12 + sinTheta * _22;
_22 = -sinTheta * temp + cosTheta * _22;
temp = _13;
_13 = cosTheta * _13 + sinTheta * _23;
_23 = -sinTheta * temp + cosTheta * _23;
temp = _14;
_14 = cosTheta * _14 + sinTheta * _24;
_24 = -sinTheta * temp + cosTheta * _24;
}
void
gfx3DMatrix::PreMultiply(const gfx3DMatrix& aOther)
{
*this = aOther * (*this);
}
void
gfx3DMatrix::PreMultiply(const gfxMatrix& aOther)
{
gfx3DMatrix temp;
temp._11 = aOther._11 * _11 + aOther._12 * _21;
temp._21 = aOther._21 * _11 + aOther._22 * _21;
temp._31 = _31;
temp._41 = aOther._31 * _11 + aOther._32 * _21 + _41;
temp._12 = aOther._11 * _12 + aOther._12 * _22;
temp._22 = aOther._21 * _12 + aOther._22 * _22;
temp._32 = _32;
temp._42 = aOther._31 * _12 + aOther._32 * _22 + _42;
temp._13 = aOther._11 * _13 + aOther._12 * _23;
temp._23 = aOther._21 * _13 + aOther._22 * _23;
temp._33 = _33;
temp._43 = aOther._31 * _13 + aOther._32 * _23 + _43;
temp._14 = aOther._11 * _14 + aOther._12 * _24;
temp._24 = aOther._21 * _14 + aOther._22 * _24;
temp._34 = _34;
temp._44 = aOther._31 * _14 + aOther._32 * _24 + _44;
*this = temp;
}
gfx3DMatrix
gfx3DMatrix::Translation(float aX, float aY, float aZ)
{
gfx3DMatrix matrix;
matrix._41 = aX;
matrix._42 = aY;
matrix._43 = aZ;
return matrix;
}
gfx3DMatrix
gfx3DMatrix::Translation(const Point3D& aPoint)
{
gfx3DMatrix matrix;
matrix._41 = aPoint.x;
matrix._42 = aPoint.y;
matrix._43 = aPoint.z;
return matrix;
}
gfx3DMatrix
gfx3DMatrix::ScalingMatrix(float aFactor)
{
gfx3DMatrix matrix;
matrix._11 = matrix._22 = matrix._33 = aFactor;
return matrix;
}
gfx3DMatrix
gfx3DMatrix::ScalingMatrix(float aX, float aY, float aZ)
{
gfx3DMatrix matrix;
matrix._11 = aX;
matrix._22 = aY;
matrix._33 = aZ;
return matrix;
}
gfxFloat
gfx3DMatrix::Determinant() const
{
return _14 * _23 * _32 * _41
- _13 * _24 * _32 * _41
- _14 * _22 * _33 * _41
+ _12 * _24 * _33 * _41
+ _13 * _22 * _34 * _41
- _12 * _23 * _34 * _41
- _14 * _23 * _31 * _42
+ _13 * _24 * _31 * _42
+ _14 * _21 * _33 * _42
- _11 * _24 * _33 * _42
- _13 * _21 * _34 * _42
+ _11 * _23 * _34 * _42
+ _14 * _22 * _31 * _43
- _12 * _24 * _31 * _43
- _14 * _21 * _32 * _43
+ _11 * _24 * _32 * _43
+ _12 * _21 * _34 * _43
- _11 * _22 * _34 * _43
- _13 * _22 * _31 * _44
+ _12 * _23 * _31 * _44
+ _13 * _21 * _32 * _44
- _11 * _23 * _32 * _44
- _12 * _21 * _33 * _44
+ _11 * _22 * _33 * _44;
}
gfxFloat
gfx3DMatrix::Determinant3x3() const
{
return _11 * (_22 * _33 - _23 * _32) +
_12 * (_23 * _31 - _33 * _21) +
_13 * (_21 * _32 - _22 * _31);
}
gfx3DMatrix
gfx3DMatrix::Inverse3x3() const
{
gfxFloat det = Determinant3x3();
if (det == 0.0) {
return *this;
}
gfxFloat detInv = 1/det;
gfx3DMatrix temp;
temp._11 = (_22 * _33 - _23 * _32) * detInv;
temp._12 = (_13 * _32 - _12 * _33) * detInv;
temp._13 = (_12 * _23 - _13 * _22) * detInv;
temp._21 = (_23 * _31 - _33 * _21) * detInv;
temp._22 = (_11 * _33 - _13 * _31) * detInv;
temp._23 = (_13 * _21 - _11 * _23) * detInv;
temp._31 = (_21 * _32 - _22 * _31) * detInv;
temp._32 = (_31 * _12 - _11 * _32) * detInv;
temp._33 = (_11 * _22 - _12 * _21) * detInv;
return temp;
}
bool
gfx3DMatrix::IsSingular() const
{
return Determinant() == 0.0;
}
gfx3DMatrix
gfx3DMatrix::Inverse() const
{
if (_14 == 0 && _24 == 0 && _34 == 0 && _44 == 1) {
/**
* When the matrix contains no perspective, the inverse
* is the same as the 3x3 inverse of the rotation components
* multiplied by the inverse of the translation components.
* Doing these steps separately is faster and more numerically
* stable.
*
* Inverse of the translation matrix is just negating
* the values.
*/
gfx3DMatrix matrix3 = Inverse3x3();
matrix3.Translate(Point3D(-_41, -_42, -_43));
return matrix3;
}
gfxFloat det = Determinant();
if (det == 0.0) {
return *this;
}
gfx3DMatrix temp;
temp._11 = _23*_34*_42 - _24*_33*_42 +
_24*_32*_43 - _22*_34*_43 -
_23*_32*_44 + _22*_33*_44;
temp._12 = _14*_33*_42 - _13*_34*_42 -
_14*_32*_43 + _12*_34*_43 +
_13*_32*_44 - _12*_33*_44;
temp._13 = _13*_24*_42 - _14*_23*_42 +
_14*_22*_43 - _12*_24*_43 -
_13*_22*_44 + _12*_23*_44;
temp._14 = _14*_23*_32 - _13*_24*_32 -
_14*_22*_33 + _12*_24*_33 +
_13*_22*_34 - _12*_23*_34;
temp._21 = _24*_33*_41 - _23*_34*_41 -
_24*_31*_43 + _21*_34*_43 +
_23*_31*_44 - _21*_33*_44;
temp._22 = _13*_34*_41 - _14*_33*_41 +
_14*_31*_43 - _11*_34*_43 -
_13*_31*_44 + _11*_33*_44;
temp._23 = _14*_23*_41 - _13*_24*_41 -
_14*_21*_43 + _11*_24*_43 +
_13*_21*_44 - _11*_23*_44;
temp._24 = _13*_24*_31 - _14*_23*_31 +
_14*_21*_33 - _11*_24*_33 -
_13*_21*_34 + _11*_23*_34;
temp._31 = _22*_34*_41 - _24*_32*_41 +
_24*_31*_42 - _21*_34*_42 -
_22*_31*_44 + _21*_32*_44;
temp._32 = _14*_32*_41 - _12*_34*_41 -
_14*_31*_42 + _11*_34*_42 +
_12*_31*_44 - _11*_32*_44;
temp._33 = _12*_24*_41 - _14*_22*_41 +
_14*_21*_42 - _11*_24*_42 -
_12*_21*_44 + _11*_22*_44;
temp._34 = _14*_22*_31 - _12*_24*_31 -
_14*_21*_32 + _11*_24*_32 +
_12*_21*_34 - _11*_22*_34;
temp._41 = _23*_32*_41 - _22*_33*_41 -
_23*_31*_42 + _21*_33*_42 +
_22*_31*_43 - _21*_32*_43;
temp._42 = _12*_33*_41 - _13*_32*_41 +
_13*_31*_42 - _11*_33*_42 -
_12*_31*_43 + _11*_32*_43;
temp._43 = _13*_22*_41 - _12*_23*_41 -
_13*_21*_42 + _11*_23*_42 +
_12*_21*_43 - _11*_22*_43;
temp._44 = _12*_23*_31 - _13*_22*_31 +
_13*_21*_32 - _11*_23*_32 -
_12*_21*_33 + _11*_22*_33;
temp /= det;
return temp;
}
gfxPoint
gfx3DMatrix::Transform(const gfxPoint& point) const
{
Point3D vec3d(point.x, point.y, 0);
vec3d = Transform3D(vec3d);
return gfxPoint(vec3d.x, vec3d.y);
}
Point3D
gfx3DMatrix::Transform3D(const Point3D& point) const
{
gfxFloat x = point.x * _11 + point.y * _21 + point.z * _31 + _41;
gfxFloat y = point.x * _12 + point.y * _22 + point.z * _32 + _42;
gfxFloat z = point.x * _13 + point.y * _23 + point.z * _33 + _43;
gfxFloat w = point.x * _14 + point.y * _24 + point.z * _34 + _44;
x /= w;
y /= w;
z /= w;
return Point3D(x, y, z);
}
Point4D
gfx3DMatrix::Transform4D(const Point4D& aPoint) const
{
gfxFloat x = aPoint.x * _11 + aPoint.y * _21 + aPoint.z * _31 + aPoint.w * _41;
gfxFloat y = aPoint.x * _12 + aPoint.y * _22 + aPoint.z * _32 + aPoint.w * _42;
gfxFloat z = aPoint.x * _13 + aPoint.y * _23 + aPoint.z * _33 + aPoint.w * _43;
gfxFloat w = aPoint.x * _14 + aPoint.y * _24 + aPoint.z * _34 + aPoint.w * _44;
return Point4D(x, y, z, w);
}
gfxRect
gfx3DMatrix::TransformBounds(const gfxRect& rect) const
{
gfxPoint points[4];
points[0] = Transform(rect.TopLeft());
points[1] = Transform(gfxPoint(rect.X() + rect.Width(), rect.Y()));
points[2] = Transform(gfxPoint(rect.X(), rect.Y() + rect.Height()));
points[3] = Transform(gfxPoint(rect.X() + rect.Width(),
rect.Y() + rect.Height()));
gfxFloat min_x, max_x;
gfxFloat min_y, max_y;
min_x = max_x = points[0].x;
min_y = max_y = points[0].y;
for (int i=1; i<4; i++) {
min_x = min(points[i].x, min_x);
max_x = max(points[i].x, max_x);
min_y = min(points[i].y, min_y);
max_y = max(points[i].y, max_y);
}
return gfxRect(min_x, min_y, max_x - min_x, max_y - min_y);
}
gfxQuad
gfx3DMatrix::TransformRect(const gfxRect& aRect) const
{
gfxPoint points[4];
points[0] = Transform(aRect.TopLeft());
points[1] = Transform(gfxPoint(aRect.X() + aRect.Width(), aRect.Y()));
points[2] = Transform(gfxPoint(aRect.X() + aRect.Width(),
aRect.Y() + aRect.Height()));
points[3] = Transform(gfxPoint(aRect.X(), aRect.Y() + aRect.Height()));
// Could this ever result in lines that intersect? I don't think so.
return gfxQuad(points[0], points[1], points[2], points[3]);
}
bool
gfx3DMatrix::Is2D() const
{
if (_13 != 0.0f || _14 != 0.0f ||
_23 != 0.0f || _24 != 0.0f ||
_31 != 0.0f || _32 != 0.0f || _33 != 1.0f || _34 != 0.0f ||
_43 != 0.0f || _44 != 1.0f) {
return false;
}
return true;
}
bool
gfx3DMatrix::Is2D(gfxMatrix* aMatrix) const
{
if (!Is2D()) {
return false;
}
if (aMatrix) {
aMatrix->_11 = _11;
aMatrix->_12 = _12;
aMatrix->_21 = _21;
aMatrix->_22 = _22;
aMatrix->_31 = _41;
aMatrix->_32 = _42;
}
return true;
}
bool
gfx3DMatrix::CanDraw2D(gfxMatrix* aMatrix) const
{
if (_14 != 0.0f ||
_24 != 0.0f ||
_44 != 1.0f) {
return false;
}
if (aMatrix) {
aMatrix->_11 = _11;
aMatrix->_12 = _12;
aMatrix->_21 = _21;
aMatrix->_22 = _22;
aMatrix->_31 = _41;
aMatrix->_32 = _42;
}
return true;
}
gfx3DMatrix&
gfx3DMatrix::ProjectTo2D()
{
_31 = 0.0f;
_32 = 0.0f;
_13 = 0.0f;
_23 = 0.0f;
_33 = 1.0f;
_43 = 0.0f;
_34 = 0.0f;
return *this;
}
Point4D gfx3DMatrix::ProjectPoint(const gfxPoint& aPoint) const
{
// Find a value for z that will transform to 0.
// The transformed value of z is computed as:
// z' = aPoint.x * _13 + aPoint.y * _23 + z * _33 + _43;
// Solving for z when z' = 0 gives us:
float z = -(aPoint.x * _13 + aPoint.y * _23 + _43) / _33;
// Compute the transformed point
return Transform4D(Point4D(aPoint.x, aPoint.y, z, 1));
}
Point3D gfx3DMatrix::GetNormalVector() const
{
// Define a plane in transformed space as the transformations
// of 3 points on the z=0 screen plane.
Point3D a = Transform3D(Point3D(0, 0, 0));
Point3D b = Transform3D(Point3D(0, 1, 0));
Point3D c = Transform3D(Point3D(1, 0, 0));
// Convert to two vectors on the surface of the plane.
Point3D ab = b - a;
Point3D ac = c - a;
return ac.CrossProduct(ab);
}
bool gfx3DMatrix::IsBackfaceVisible() const
{
// Inverse()._33 < 0;
gfxFloat det = Determinant();
float _33 = _12*_24*_41 - _14*_22*_41 +
_14*_21*_42 - _11*_24*_42 -
_12*_21*_44 + _11*_22*_44;
return (_33 * det) < 0;
}
void gfx3DMatrix::NudgeToIntegers(void)
{
NudgeToInteger(&_11);
NudgeToInteger(&_12);
NudgeToInteger(&_13);
NudgeToInteger(&_14);
NudgeToInteger(&_21);
NudgeToInteger(&_22);
NudgeToInteger(&_23);
NudgeToInteger(&_24);
NudgeToInteger(&_31);
NudgeToInteger(&_32);
NudgeToInteger(&_33);
NudgeToInteger(&_34);
NudgeToInteger(&_41);
NudgeToInteger(&_42);
NudgeToInteger(&_43);
NudgeToInteger(&_44);
}
void gfx3DMatrix::NudgeToIntegersFixedEpsilon(void)
{
NudgeToInteger(&_11);
NudgeToInteger(&_12);
NudgeToInteger(&_13);
NudgeToInteger(&_14);
NudgeToInteger(&_21);
NudgeToInteger(&_22);
NudgeToInteger(&_23);
NudgeToInteger(&_24);
NudgeToInteger(&_31);
NudgeToInteger(&_32);
NudgeToInteger(&_33);
NudgeToInteger(&_34);
static const float error = 1e-5;
NudgeToInteger(&_41, error);
NudgeToInteger(&_42, error);
NudgeToInteger(&_43, error);
NudgeToInteger(&_44, error);
}
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