void FrustumFieldMapping::setTransforms(float t,
const M44d &ssToWs, const M44d &csToWs)
{
if (m_defaultState) {
clearCurves();
m_defaultState = false;
}
// Construct local-to-world transform from ssToWs
M44d lsToSs, scale, translation;
scale.setScale(V3d(2.0, 2.0, 1.0));
translation.setTranslation(V3d(-1.0, -1.0, 0.0));
lsToSs = scale * translation;
M44d lpsToWs = lsToSs * ssToWs;
// Add samples to Curves
m_ssToWsCurve.addSample(t, ssToWs);
m_lpsToWsCurve.addSample(t, lpsToWs);
m_csToWsCurve.addSample(t, csToWs);
// Compute near and far planes ---
// Because the frustum may be skewed we can't just measure distance from
// the apex of the frustum to the world-space center point of the frustum.
// Instead, we transform into camera space and measure z depth there.
V3d lsNearP(0.5, 0.5, 0.0), lsFarP(0.5, 0.5, 1.0);
V3d wsNearP, wsFarP, csNearP, csFarP;
lpsToWs.multVecMatrix(lsNearP, wsNearP);
lpsToWs.multVecMatrix(lsFarP, wsFarP);
M44d wsToCs = csToWs.inverse();
wsToCs.multVecMatrix(wsNearP, csNearP);
wsToCs.multVecMatrix(wsFarP, csFarP);
double near = -csNearP.z;
double far = -csFarP.z;
// Catch NaN here
if (isnan(near) || isnan(far)) {
throw BadPerspectiveMatrix("FrustumFieldMapping::setTransforms "
"received bad screen-to-world matrix");
}
m_nearCurve.addSample(t, near);
m_farCurve.addSample(t, far);
computeVoxelSize();
}
/// Guess position in 3D corresponding to a 2D click
///
/// `clickPos` - 2D position in viewport, as from a mouse event.
Imath::V3d View3D::guessClickPosition(const QPoint& clickPos)
{
// Get new point in the projected coordinate system using the click
// position x,y and the z of a reference position. Take the reference point
// of interest to be between the camera rotation center and the camera
// position, as a rough guess of the depth the user is interested in.
//
// This works pretty well, except when there are noise points intervening
// between the reference position and the user's actual point of interest.
V3d refPos = 0.3*m_camera.position() + 0.7*m_camera.center();
M44d mat = m_camera.viewMatrix()*m_camera.projectionMatrix()*m_camera.viewportMatrix();
double refZ = (refPos * mat).z;
V3d newPointProj(clickPos.x(), clickPos.y(), refZ);
// Map projected point back into model coordinates
return newPointProj * mat.inverse();
}
void FrustumFieldMapping::reset()
{
// Default camera to world ---
M44d csToWs;
csToWs.makeIdentity();
// Default screen to world ---
double near = 1;
double far = 2;
double fovRadians = 45.0 * M_PI / 180.0;
double invTan = 1.0 / std::tan(fovRadians / 2.0);
double imageAspectRatio = 1.0;
M44d perspective(1, 0, 0, 0,
0, 1, 0, 0,
0, 0, (far) / (far - near), 1,
0, 0, (- far * near) / (far - near), 0);
M44d fov;
fov.setScale(V3d(invTan / imageAspectRatio, invTan, 1.0));
M44d flipZ;
flipZ.setScale(V3d(1.0, 1.0, -1.0));
M44d csToSs = flipZ * perspective * fov;
M44d standardSsToWs = csToSs.inverse() * csToWs;
// Set default state ---
clearCurves();
setTransforms(standardSsToWs, csToWs);
m_defaultState = true;
computeVoxelSize();
}
void MatrixFieldMapping::updateTransform()
{
typedef MatrixCurve::SampleVec::const_iterator SampleIter;
// Build the voxel to world space transforms ---
M44d lsToVs;
getLocalToVoxelMatrix(lsToVs);
M44d vsToLs = lsToVs.inverse();
// Loop over all samples in lsToWs, append vsToLs and create new curve
// Also handle the special case where lsToWs has no samples. In that
// case m_vsToWsCurve still has to have one sample.
const MatrixCurve::SampleVec &lsToWs = m_lsToWsCurve.samples();
m_vsToWsCurve.clear();
for (SampleIter i = lsToWs.begin(), end = lsToWs.end(); i != end; i++) {
m_vsToWsCurve.addSample(i->first, vsToLs * i->second);
}
// See if the curve has more than just a single sample
m_isTimeVarying = m_lsToWsCurve.numSamples() > 1;
// Sample the time-varying transforms at time=0.0
m_lsToWs = m_lsToWsCurve.linear(0.0);
m_wsToLs = m_lsToWs.inverse();
m_vsToWs = vsToLs * m_lsToWs;
m_wsToVs = m_vsToWs.inverse();
// Precompute the voxel size
V3d voxelOrigin, nextVoxel;
m_vsToWs.multVecMatrix(V3d(0, 0, 0), voxelOrigin);
m_vsToWs.multVecMatrix(V3d(1, 0, 0), nextVoxel);
m_wsVoxelSize.x = (nextVoxel - voxelOrigin).length();
m_vsToWs.multVecMatrix(V3d(0, 1, 0), nextVoxel);
m_wsVoxelSize.y = (nextVoxel - voxelOrigin).length();
m_vsToWs.multVecMatrix(V3d(0, 0, 1), nextVoxel);
m_wsVoxelSize.z = (nextVoxel - voxelOrigin).length();
}
