gfx/2d/Matrix.cpp
 author Robert O'Callahan Wed, 22 Oct 2014 11:01:00 +1300 changeset 225867 acd99fc02446 parent 222784 d02d8790e5c5 permissions -rw-r--r--
Bug 1081185 - Traverse rect edges when searching for w=0 crossings instead of taking diagonals. r=mattwoodrow, a=lmandel
```
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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 "Matrix.h"
#include "Tools.h"
#include <algorithm>
#include <math.h>

#include "mozilla/FloatingPoint.h" // for UnspecifiedNaN

using namespace std;

namespace mozilla {
namespace gfx {

Matrix
Matrix::Rotation(Float aAngle)
{
Matrix newMatrix;

Float s = sin(aAngle);
Float c = cos(aAngle);

newMatrix._11 = c;
newMatrix._12 = s;
newMatrix._21 = -s;
newMatrix._22 = c;

return newMatrix;
}

Rect
Matrix::TransformBounds(const Rect &aRect) const
{
int i;
Float min_x, max_x;
Float min_y, max_y;

for (i = 1; i < 4; i++) {

}

return Rect(min_x, min_y, max_x - min_x, max_y - min_y);
}

void
Matrix::NudgeToIntegers()
{
NudgeToInteger(&_11);
NudgeToInteger(&_12);
NudgeToInteger(&_21);
NudgeToInteger(&_22);
NudgeToInteger(&_31);
NudgeToInteger(&_32);
}

Rect
Matrix4x4::TransformBounds(const Rect& aRect) const
{
Float min_x, max_x;
Float min_y, max_y;

for (int i = 1; i < 4; i++) {
}
}

}
}
}

return Rect(min_x, min_y, max_x - min_x, max_y - min_y);
}

Point4D ComputePerspectivePlaneIntercept(const Point4D& aFirst,
const Point4D& aSecond)
{
// FIXME: See bug 1035611
// Since we can't easily deal with points as w=0 (since we divide by w), we
// approximate this by finding a point with w just greater than 0. Unfortunately
// this is a tradeoff between accuracy and floating point precision.

// We want to interpolate aFirst and aSecond to find a point as close to
// the positive side of the w=0 plane as possible.

// Since we know what we want the w component to be, we can rearrange the
// interpolation equation and solve for t.
float w = 0.00001f;
float t = (w - aFirst.w) / (aSecond.w - aFirst.w);

// Use t to find the remainder of the components
return aFirst + (aSecond - aFirst) * t;
}

Rect Matrix4x4::ProjectRectBounds(const Rect& aRect) const
{
Point4D points[4];

points[0] = ProjectPoint(aRect.TopLeft());
points[1] = ProjectPoint(aRect.TopRight());
points[2] = ProjectPoint(aRect.BottomRight());
points[3] = ProjectPoint(aRect.BottomLeft());

Float min_x = std::numeric_limits<Float>::max();
Float min_y = std::numeric_limits<Float>::max();
Float max_x = -std::numeric_limits<Float>::max();
Float max_y = -std::numeric_limits<Float>::max();

bool foundPoint = false;
for (int i=0; i<4; i++) {
// Only use points that exist above the w=0 plane
if (points[i].HasPositiveWCoord()) {
foundPoint = true;
Point point2d = points[i].As2DPoint();
min_x = min<Float>(point2d.x, min_x);
max_x = max<Float>(point2d.x, max_x);
min_y = min<Float>(point2d.y, min_y);
max_y = max<Float>(point2d.y, max_y);
}

int next = (i == 3) ? 0 : i + 1;
if (points[i].HasPositiveWCoord() != points[next].HasPositiveWCoord()) {
// If the line between two points crosses the w=0 plane, then interpolate a point
// as close to the w=0 plane as possible and use that instead.
Point4D intercept = ComputePerspectivePlaneIntercept(points[i], points[next]);

Point point2d = intercept.As2DPoint();
min_x = min<Float>(point2d.x, min_x);
max_x = max<Float>(point2d.x, max_x);
min_y = min<Float>(point2d.y, min_y);
max_y = max<Float>(point2d.y, max_y);
}
}

if (!foundPoint) {
return Rect(0, 0, 0, 0);
}

return Rect(min_x, min_y, max_x - min_x, max_y - min_y);
}

bool
Matrix4x4::Invert()
{
Float det = Determinant();
if (!det) {
return false;
}

Matrix4x4 result;
result._11 = _23 * _34 * _42 - _24 * _33 * _42 + _24 * _32 * _43 - _22 * _34 * _43 - _23 * _32 * _44 + _22 * _33 * _44;
result._12 = _14 * _33 * _42 - _13 * _34 * _42 - _14 * _32 * _43 + _12 * _34 * _43 + _13 * _32 * _44 - _12 * _33 * _44;
result._13 = _13 * _24 * _42 - _14 * _23 * _42 + _14 * _22 * _43 - _12 * _24 * _43 - _13 * _22 * _44 + _12 * _23 * _44;
result._14 = _14 * _23 * _32 - _13 * _24 * _32 - _14 * _22 * _33 + _12 * _24 * _33 + _13 * _22 * _34 - _12 * _23 * _34;
result._21 = _24 * _33 * _41 - _23 * _34 * _41 - _24 * _31 * _43 + _21 * _34 * _43 + _23 * _31 * _44 - _21 * _33 * _44;
result._22 = _13 * _34 * _41 - _14 * _33 * _41 + _14 * _31 * _43 - _11 * _34 * _43 - _13 * _31 * _44 + _11 * _33 * _44;
result._23 = _14 * _23 * _41 - _13 * _24 * _41 - _14 * _21 * _43 + _11 * _24 * _43 + _13 * _21 * _44 - _11 * _23 * _44;
result._24 = _13 * _24 * _31 - _14 * _23 * _31 + _14 * _21 * _33 - _11 * _24 * _33 - _13 * _21 * _34 + _11 * _23 * _34;
result._31 = _22 * _34 * _41 - _24 * _32 * _41 + _24 * _31 * _42 - _21 * _34 * _42 - _22 * _31 * _44 + _21 * _32 * _44;
result._32 = _14 * _32 * _41 - _12 * _34 * _41 - _14 * _31 * _42 + _11 * _34 * _42 + _12 * _31 * _44 - _11 * _32 * _44;
result._33 = _12 * _24 * _41 - _14 * _22 * _41 + _14 * _21 * _42 - _11 * _24 * _42 - _12 * _21 * _44 + _11 * _22 * _44;
result._34 = _14 * _22 * _31 - _12 * _24 * _31 - _14 * _21 * _32 + _11 * _24 * _32 + _12 * _21 * _34 - _11 * _22 * _34;
result._41 = _23 * _32 * _41 - _22 * _33 * _41 - _23 * _31 * _42 + _21 * _33 * _42 + _22 * _31 * _43 - _21 * _32 * _43;
result._42 = _12 * _33 * _41 - _13 * _32 * _41 + _13 * _31 * _42 - _11 * _33 * _42 - _12 * _31 * _43 + _11 * _32 * _43;
result._43 = _13 * _22 * _41 - _12 * _23 * _41 - _13 * _21 * _42 + _11 * _23 * _42 + _12 * _21 * _43 - _11 * _22 * _43;
result._44 = _12 * _23 * _31 - _13 * _22 * _31 + _13 * _21 * _32 - _11 * _23 * _32 - _12 * _21 * _33 + _11 * _22 * _33;

result._11 /= det;
result._12 /= det;
result._13 /= det;
result._14 /= det;
result._21 /= det;
result._22 /= det;
result._23 /= det;
result._24 /= det;
result._31 /= det;
result._32 /= det;
result._33 /= det;
result._34 /= det;
result._41 /= det;
result._42 /= det;
result._43 /= det;
result._44 /= det;
*this = result;

return true;
}

void
Matrix4x4::SetNAN()
{
_11 = UnspecifiedNaN<Float>();
_21 = UnspecifiedNaN<Float>();
_31 = UnspecifiedNaN<Float>();
_41 = UnspecifiedNaN<Float>();
_12 = UnspecifiedNaN<Float>();
_22 = UnspecifiedNaN<Float>();
_32 = UnspecifiedNaN<Float>();
_42 = UnspecifiedNaN<Float>();
_13 = UnspecifiedNaN<Float>();
_23 = UnspecifiedNaN<Float>();
_33 = UnspecifiedNaN<Float>();
_43 = UnspecifiedNaN<Float>();
_14 = UnspecifiedNaN<Float>();
_24 = UnspecifiedNaN<Float>();
_34 = UnspecifiedNaN<Float>();
_44 = UnspecifiedNaN<Float>();
}

}
}
```