void GLRenderSystemCommon::_makeOrthoMatrix(const Radian& fovy, Real aspect,
Real nearPlane, Real farPlane,
Matrix4& dest, bool forGpuProgram)
{
Radian thetaY(fovy / 2.0f);
Real tanThetaY = Math::Tan(thetaY);
// Real thetaX = thetaY * aspect;
Real tanThetaX = tanThetaY * aspect; // Math::Tan(thetaX);
Real half_w = tanThetaX * nearPlane;
Real half_h = tanThetaY * nearPlane;
Real iw = 1.0f / half_w;
Real ih = 1.0f / half_h;
Real q;
if (farPlane == 0)
{
q = 0;
}
else
{
q = 2.0f / (farPlane - nearPlane);
}
dest = Matrix4::ZERO;
dest[0][0] = iw;
dest[1][1] = ih;
dest[2][2] = -q;
dest[2][3] = -(farPlane + nearPlane) / (farPlane - nearPlane);
dest[3][3] = 1;
}
void GLRenderSystemCommon::_makeProjectionMatrix(const Radian& fovy, Real aspect,
Real nearPlane, Real farPlane,
Matrix4& dest, bool forGpuProgram)
{
Radian thetaY(fovy / 2.0f);
Real tanThetaY = Math::Tan(thetaY);
// Calc matrix elements
Real w = (1.0f / tanThetaY) / aspect;
Real h = 1.0f / tanThetaY;
Real q, qn;
if (farPlane == 0)
{
// Infinite far plane
q = Frustum::INFINITE_FAR_PLANE_ADJUST - 1;
qn = nearPlane * (Frustum::INFINITE_FAR_PLANE_ADJUST - 2);
}
else
{
q = -(farPlane + nearPlane) / (farPlane - nearPlane);
qn = -2 * (farPlane * nearPlane) / (farPlane - nearPlane);
}
// NB This creates Z in range [-1,1]
//
// [ w 0 0 0 ]
// [ 0 h 0 0 ]
// [ 0 0 q qn ]
// [ 0 0 -1 0 ]
dest = Matrix4::ZERO;
dest[0][0] = w;
dest[1][1] = h;
dest[2][2] = q;
dest[2][3] = qn;
dest[3][2] = -1;
}
//-----------------------------------------------------------------------
void Frustum::calcProjectionParameters(Real& left, Real& right, Real& bottom, Real& top) const
{
if (mCustomProjMatrix) //自定义投影矩阵
{
// 转换剪裁平面角到相机空间中
Matrix4 invProj = mProjMatrix.inverse(); //对透视投影矩阵求逆得观察矩阵
Vector3 topLeft(-0.5f, 0.5f, 0.0f); //左上角
Vector3 bottomRight(0.5f, -0.5f, 0.0f); //右下角
topLeft = invProj * topLeft;
bottomRight = invProj * bottomRight;
left = topLeft.x;
top = topLeft.y;
right = bottomRight.x;
bottom = bottomRight.y;
}
else
{
//视锥体手动扩展设置
if (mFrustumExtentsManuallySet)
{
left = mLeft;
right = mRight;
top = mTop;
bottom = mBottom;
}
// 计算通用的投影参数
else if (mProjType == PT_PERSPECTIVE) //透视投影
{
Radian thetaY(mFOVy * 0.5f); //thetaY= mFovy的一半
Real tanThetaY = Math::Tan(thetaY);
Real tanThetaX = tanThetaY * mAspect;
//用于3d立体显示参数
Real nearFocal = mNearDist / mFocalLength;
Real nearOffsetX = mFrustumOffset.x * nearFocal;
Real nearOffsetY = mFrustumOffset.y * nearFocal;
Real half_w = tanThetaX * mNearDist;
Real half_h = tanThetaY * mNearDist;
left = -half_w + nearOffsetX;
right = +half_w + nearOffsetX;
bottom = -half_h + nearOffsetY;
top = +half_h + nearOffsetY;
mLeft = left;
mRight = right;
mTop = top;
mBottom = bottom;
}
else
{
//正交投影
// 不知道怎样应用视锥体偏移到正交投影相机，这里就无效化
Real half_w = getOrthoWindowWidth() * 0.5f;
Real half_h = getOrthoWindowHeight() * 0.5f;
left = -half_w;
right = +half_w;
bottom = -half_h;
top = +half_h;
mLeft = left;
mRight = right;
mTop = top;
mBottom = bottom;
}
}
}
