bool RaySphereTest(const M3DVector3f point, const M3DVector3f ray, const M3DVector3f sphereCenter, float sphereRadius)
{
//m3dNormalizeVectorf(ray); // Make sure ray is unit length
M3DVector3f rayToCenter; // Ray to center of sphere
rayToCenter[0] = sphereCenter[0] - point[0];
rayToCenter[1] = sphereCenter[1] - point[1];
rayToCenter[2] = sphereCenter[2] - point[2];
// Project rayToCenter on ray to test
float a = m3dDotProduct3(rayToCenter, ray);
// Distance to center of sphere
float distance2 = m3dDotProduct3(rayToCenter, rayToCenter); // Or length
float dRet = (sphereRadius * sphereRadius) - distance2 + (a*a);
if(dRet > 0.0) // Return distance to intersection
return true;
dRet = a - sqrtf(dRet);
return false;
}
///////////////////////////////////////////////////////////////////////////////
// Determine if the ray (starting at point) intersects the sphere centered at
// sphereCenter with radius sphereRadius
// Return value is < 0 if the ray does not intersect
// Return value is 0.0 if ray is tangent
// Positive value is distance to the intersection point
// Algorithm from "3D Math Primer for Graphics and Game Development"
double m3dRaySphereTest(const M3DVector3d point, const M3DVector3d ray, const M3DVector3d sphereCenter, double sphereRadius)
{
//m3dNormalizeVector(ray); // Make sure ray is unit length
M3DVector3d rayToCenter; // Ray to center of sphere
rayToCenter[0] = sphereCenter[0] - point[0];
rayToCenter[1] = sphereCenter[1] - point[1];
rayToCenter[2] = sphereCenter[2] - point[2];
// Project rayToCenter on ray to test
double a = m3dDotProduct3(rayToCenter, ray);
// Distance to center of sphere
double distance2 = m3dDotProduct3(rayToCenter, rayToCenter); // Or length
double dRet = (sphereRadius * sphereRadius) - distance2 + (a*a);
if(dRet > 0.0) // Return distance to intersection
dRet = a - sqrt(dRet);
return dRet;
}
// ditto above... but with floats
float m3dClosestPointOnRay(M3DVector3f vPointOnRay, const M3DVector3f vRayOrigin, const M3DVector3f vUnitRayDir,
const M3DVector3f vPointInSpace)
{
M3DVector3f v;
m3dSubtractVectors3(v, vPointInSpace, vRayOrigin);
float t = m3dDotProduct3(vUnitRayDir, v);
// This is the point on the ray
vPointOnRay[0] = vRayOrigin[0] + (t * vUnitRayDir[0]);
vPointOnRay[1] = vRayOrigin[1] + (t * vUnitRayDir[1]);
vPointOnRay[2] = vRayOrigin[2] + (t * vUnitRayDir[2]);
return m3dGetDistanceSquared3(vPointOnRay, vPointInSpace);
}
void MouseMoveEvent(int x, int y)
{
if (isStartTrackBall)
{
GLfloat theta;
M3DVector3f p1, p2, n;
int width = glutGet(GLUT_WINDOW_WIDTH);
int height = glutGet(GLUT_WINDOW_HEIGHT);
MousePtToSphereVec(p1, mMouseX, mMouseY, width, height);
MousePtToSphereVec(p2, x, y, width, height);
mMouseX = x;
mMouseY = y;
m3dNormalizeVector3(p1);
m3dNormalizeVector3(p2);
theta = acos(m3dDotProduct3(p1, p2)) ;
//theta = m3dGetAngleBetweenVectors3(p1, p2);
m3dCrossProduct3(n, p1, p2);
m3dNormalizeVector3(n);
M3DMatrix44f tempRotation;
m3dLoadIdentity44(tempRotation);
GLfloat dis = m3dGetDistance3(p1, p2);
if (dis != 0.0f)
{
m3dRotationMatrix44(tempRotation, theta, m3dGetVectorX(n), m3dGetVectorY(n), m3dGetVectorZ(n));
}
m3dMatrixMultiply44(mRotation, tempRotation, mRotation);
glutPostRedisplay();
}
}
