//-----------------------------------------------------------------------
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;
}
}
}
//-----------------------------------------------------------------------
void Frustum::calcProjectionParameters(Real& left, Real& right, Real& bottom, Real& top) const
{
if (mCustomProjMatrix)
{
// Convert clipspace corners to camera space
Matrix4 invProj = mProjMatrix.inverse();
Vector3 topLeft(-0.5f, 0.5f, 0.0f);
Vector3 bottomRight(0.5f, -0.5f, 0.0f);
topLeft = invProj * topLeft;
bottomRight = invProj * bottomRight;
left = topLeft.x;
top = topLeft.y;
right = bottomRight.x;
bottom = bottomRight.y;
}
else
{
if (mFrustumExtentsManuallySet)
{
left = mLeft;
right = mRight;
top = mTop;
bottom = mBottom;
}
// Calculate general projection parameters
else if (mProjType == PT_PERSPECTIVE)
{
Radian thetaY (mFOVy * 0.5f);
Real tanThetaY = Math::Tan(thetaY);
Real tanThetaX = tanThetaY * mAspect;
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
{
// Unknown how to apply frustum offset to orthographic camera, just ignore here
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;
}
}
}