//-------------------------------------------------------------------------------
// @ ::BarycentricCoordinates()
//-------------------------------------------------------------------------------
// Returns barycentric coordinates for point inside triangle (3D version)
// Assumes triangle is not degenerate
//-------------------------------------------------------------------------------
void BarycentricCoordinates( float &r, float &s, float& t,
const IvVector3& point, const IvVector3& P0,
const IvVector3& P1, const IvVector3& P2 )
{
// get difference vectors
IvVector3 u = P1 - P0;
IvVector3 v = P2 - P0;
IvVector3 w = point - P0;
// compute cross product to get area of parallelograms
IvVector3 a = u.Cross(w);
IvVector3 b = v.Cross(w);
IvVector3 c = u.Cross(v);
// compute barycentric coordinates as ratios of areas
float denom = 1.0f/c.Length();
s = b.Length()*denom;
t = a.Length()*denom;
r = 1.0f - s - t;
}
//-------------------------------------------------------------------------------
// @ ::TriangleIntersect()
//-------------------------------------------------------------------------------
// Returns true if ray intersects triangle
//-------------------------------------------------------------------------------
bool
TriangleIntersect( float& t, const IvVector3& P0, const IvVector3& P1,
const IvVector3& P2, const IvRay3& ray )
{
// test ray direction against triangle
IvVector3 e1 = P1 - P0;
IvVector3 e2 = P2 - P0;
IvVector3 p = ray.GetDirection().Cross(e2);
float a = e1.Dot(p);
// if result zero, no intersection or infinite intersections
// (ray parallel to triangle plane)
if ( IvIsZero(a) )
return false;
// compute denominator
float f = 1.0f/a;
// compute barycentric coordinates
IvVector3 s = ray.GetOrigin() - P0;
float u = f*s.Dot(p);
// ray falls outside triangle
if (u < 0.0f || u > 1.0f)
return false;
IvVector3 q = s.Cross(e1);
float v = f*ray.GetDirection().Dot(q);
// ray falls outside triangle
if (v < 0.0f || u+v > 1.0f)
return false;
// compute line parameter
t = f*e2.Dot(q);
return (t >= 0.0f);
}
//-------------------------------------------------------------------------------
// @ IvQuat::Set()
//-------------------------------------------------------------------------------
// Set quaternion based on start and end vectors
//-------------------------------------------------------------------------------
void
IvQuat::Set( const IvVector3& from, const IvVector3& to )
{
// Ensure that our vectors are unit
ASSERT( from.IsUnit() && to.IsUnit() );
// get axis of rotation
IvVector3 axis = from.Cross( to );
// get cos of angle between vectors
float costheta = from.Dot( to );
// if vectors are 180 degrees apart
if ( costheta <= -1.0f )
{
// find orthogonal vector
IvVector3 orthoVector;
orthoVector.Normalize();
w = 0.0f;
x = orthoVector.x;
y = orthoVector.y;
z = orthoVector.z;
return;
}
// use trig identities to get the values we want
float factor = IvSqrt( 2.0f*(1.0f + costheta) );
float scaleFactor = 1.0f/factor;
// set values
w = 0.5f*factor;
x = scaleFactor*axis.x;
y = scaleFactor*axis.y;
z = scaleFactor*axis.z;
} // End of IvQuat::Set()
//-------------------------------------------------------------------------------
// @ Player::Update()
//-------------------------------------------------------------------------------
// Main update loop
//-------------------------------------------------------------------------------
void
Player::Update( float dt )
{
// update based on input
if (IvGame::mGame->mEventHandler->IsKeyPressed(' '))
{
if (mRun)
{
mTime = 0.0f;
mRun = false;
}
else
{
mRun = true;
}
}
if (IvGame::mGame->mEventHandler->IsKeyPressed('m'))
{
mMode = (mMode + 1)%4;
}
if (mRun)
{
mTime += dt;
// stop just before end so we don't end up with zero vector
// when we look ahead
if ( mTime > 11.5f )
mTime = 11.5f;
}
// now we set up the camera
// get eye position
IvVector3 eye = mCurve.Evaluate( mTime );
IvVector3 viewDir;
IvVector3 viewSide;
IvVector3 viewUp;
// set parameters depending on what mode we're in
// Frenet frame
if ( mMode == 3 )
{
IvVector3 T = mCurve.Velocity( mTime );
IvVector3 a = mCurve.Acceleration( mTime );
IvVector3 B = T.Cross( a );
B.Normalize();
T.Normalize();
IvVector3 N = B.Cross( T );
viewDir = T;
viewSide = -N; // have to negate to get from RH frame to LH frame
viewUp = B;
}
else
{
IvVector3 lookAt;
// look same direction all the time
if ( mMode == 2 )
{
viewDir = IvVector3::xAxis;
}
// look along tangent
else if ( mMode == 1 )
{
viewDir = mCurve.Velocity( mTime );
}
// look ahead .5 in parameter
else if ( mMode == 0 )
{
viewDir = mCurve.Evaluate( mTime+0.5f ) - eye;
}
// compute view vectors
viewDir.Normalize();
viewUp = IvVector3::zAxis - IvVector3::zAxis.Dot(viewDir)*viewDir;
viewUp.Normalize();
viewSide = viewDir.Cross(viewUp);
}
// now set up matrices
// build transposed rotation matrix
IvMatrix33 rotate;
if ( IvRenderer::mRenderer->GetAPI() == kOpenGL )
{
rotate.SetRows( viewSide, viewUp, -viewDir );
}
else
{
rotate.SetRows( viewSide, viewUp, viewDir );
}
// transform translation
IvVector3 eyeInv = -(rotate*eye);
// build 4x4 matrix
IvMatrix44 matrix(rotate);
matrix(0,3) = eyeInv.x;
matrix(1,3) = eyeInv.y;
matrix(2,3) = eyeInv.z;
::IvSetViewMatrix( matrix );
} // End of Player::Update()
