bool UnitSquare::intersect( Ray3D& ray, const Matrix4x4& worldToModel,
const Matrix4x4& modelToWorld ) {
// TODO: implement intersection code for UnitSquare, which is
// defined on the xy-plane, with vertices (0.5, 0.5, 0),
// (-0.5, 0.5, 0), (-0.5, -0.5, 0), (0.5, -0.5, 0), and normal
// (0, 0, 1).
//
// Your goal here is to fill ray.intersection with correct values
// should an intersection occur. This includes intersection.point,
// intersection.normal, intersection.none, intersection.t_hit.
//
// HINT: Remember to first transform the ray into object space
// to simplify the intersection test.
Ray3D modelRay; // To store transformed model space ray.
Vector3D surfaceNormal(0, 0, 1); // Constant surface normal.
double t; // Intersection parameter.
// Transform ray to model space.
modelRay.origin = worldToModel * ray.origin;
modelRay.dir = worldToModel * ray.dir;;
// Compute intersection between ray and XY-plane.
double d_dot_n = modelRay.dir.dot(surfaceNormal);
// TODO: NEED MORE STABLE FLOAT EQUAL CHECK!
if (d_dot_n == 0.0) {
// Ray is parallel to plane.
return false;
}
// Compute intersection and check if it occurs infront or behind the camera.
t = -(Vector3D(modelRay.origin[0], modelRay.origin[1], modelRay.origin[2]).dot(surfaceNormal)) / d_dot_n;
if (t < ray.intersection.t_min || t > ray.intersection.t_max) {
return false;
}
if (!ray.intersection.none && t > ray.intersection.t_hit) {
return false;
}
// Compute intersection point and check againt unit square bounds.
Point3D intPoint = modelRay.origin + (t * modelRay.dir);
if (!(intPoint[0] >= -0.5 && intPoint[0] <= 0.5 &&
intPoint[1] >= -0.5 && intPoint[1] <= 0.5)) {
return false;
}
// Transform and set intersection info.
ray.intersection.point = modelToWorld * intPoint;
ray.intersection.normal = transNorm(worldToModel, surfaceNormal);
ray.intersection.normal.normalize();
ray.intersection.t_hit = t;
ray.intersection.none = false;
ray.intersection.inside = false;
return true;
}
/* recalcul des normales */
void updtNorms(void)
{
int i,j;
int ptrFlSize = sizeof(GLfloat*);
char errMsg[] = "Erreur après realloc.";
/* normales des faces dans lesquelles les sommets sont compris */
GLfloat** vrtxFacesNorm[VERTICES_BOX01];
GLfloat faceNormals[FACES_BOX01][3];
GLint currSize[VERTICES_BOX01];
for(i = 0; i < FACES_BOX01; i++)
surfaceNormal(
&vertices[3*faces[i][0]],
&vertices[3*faces[i][1]],
&vertices[3*faces[i][2]],
&faceNormals[i][0]);
memset(currSize, 0, VERTICES_BOX01*sizeof(GLint));
memset(vrtxFacesNorm, 0, VERTICES_BOX01*sizeof(GLfloat**));
/* initialisaition de vrtxFacesNorm */
for(i = 0; i < FACES_BOX01; i++)
{
for(j = 0; j < 3; j++)
{
currSize[faces[i][j]]++;
vrtxFacesNorm[faces[i][j]] =
(GLfloat**)realloc(vrtxFacesNorm[faces[i][j]],
currSize[faces[i][j]]*ptrFlSize);
if (vrtxFacesNorm[faces[i][j]] == NULL)
{
// AnsiToOem(errMsg, errMsg);
printf(errMsg);
exit(1);
}
vrtxFacesNorm[faces[i][j]][currSize[faces[i][j]]-1] =
&faceNormals[i][0];
}
}
/* calcul des normales des sommets */
for(i = 0; i < VERTICES_BOX01; i++)
vertexNormal(vrtxFacesNorm[i], currSize[i], &norm[i*3]);
}
// vMarchCube1 performs the Marching Cubes algorithm on a single cube
GLvoid MarchingCubes::vMarchCube1(const GLint &iX, const GLint &iY, const GLint &iZ,
const GLfloat& isoValue)
{
GLfloat fX(iX*m_stepSize);
GLfloat fY(iY*m_stepSize);
GLfloat fZ(iZ*m_stepSize);
GLint iCorner, iVertex, iVertexTest, iEdge, iTriangle, iFlagIndex, iEdgeFlags;
GLfloat fOffset;
GLfloat afCubeValue[8];
GLvector asEdgeVertex[12];
GLvector asEdgeNorm[12];
// Make a local copy of the values at the cube's corners
for (iVertex = 0; iVertex < 8; iVertex++) {
afCubeValue[iVertex] = (*m_grid)(iX + s_vertexIndexOffset[iVertex][0],
iY + s_vertexIndexOffset[iVertex][1],
iZ + s_vertexIndexOffset[iVertex][2]);
}
// Find which vertices are inside of the surface and which are outside
iFlagIndex = 0;
for (iVertexTest = 0; iVertexTest < 8; iVertexTest++) {
if (afCubeValue[iVertexTest] <= isoValue) iFlagIndex |= 1<<iVertexTest;
}
// Find which edges are intersected by the surface
iEdgeFlags = s_cubeEdgeFlags[iFlagIndex];
// If the cube is entirely inside or outside of the surface, then there will
// be no intersections
if(iEdgeFlags == 0) return;
// Find the point of intersection of the surface with each edge
// Then find the normal to the surface at those points
for (iEdge = 0; iEdge < 12; iEdge++) {
// if there is an intersection on this edge
if (iEdgeFlags & (1<<iEdge)) {
fOffset = getOffset(afCubeValue[ s_edgeConnection[iEdge][0] ],
afCubeValue[ s_edgeConnection[iEdge][1] ], isoValue);
asEdgeVertex[iEdge].fX = fX + (s_vertexOffset[ s_edgeConnection[iEdge][0] ][0] +
fOffset * s_edgeDirection[iEdge][0]) * m_stepSize;
asEdgeVertex[iEdge].fY = fY + (s_vertexOffset[ s_edgeConnection[iEdge][0] ][1] +
fOffset * s_edgeDirection[iEdge][1]) * m_stepSize;
asEdgeVertex[iEdge].fZ = fZ + (s_vertexOffset[ s_edgeConnection[iEdge][0] ][2] +
fOffset * s_edgeDirection[iEdge][2]) * m_stepSize;
surfaceNormal(asEdgeNorm[iEdge], asEdgeVertex[iEdge].fX,
asEdgeVertex[iEdge].fY, asEdgeVertex[iEdge].fZ);
if (isoValue < 0) {
asEdgeNorm[iEdge].fX = - asEdgeNorm[iEdge].fX;
asEdgeNorm[iEdge].fY = - asEdgeNorm[iEdge].fY;
asEdgeNorm[iEdge].fZ = - asEdgeNorm[iEdge].fZ;
}
}
}
// Draw the triangles that were found. There can be up to five per cube
for (iTriangle = 0; iTriangle < 5; iTriangle++) {
if (s_triangleConnectionTable[iFlagIndex][3*iTriangle] < 0) break;
for (iCorner = 0; iCorner < 3; iCorner++) {
iVertex = s_triangleConnectionTable[iFlagIndex][3*iTriangle+iCorner];
m_surfaceData.push_back(asEdgeNorm[iVertex].fX);
m_surfaceData.push_back(asEdgeNorm[iVertex].fY);
m_surfaceData.push_back(asEdgeNorm[iVertex].fZ);
m_surfaceData.push_back(asEdgeVertex[iVertex].fX);
m_surfaceData.push_back(asEdgeVertex[iVertex].fY);
m_surfaceData.push_back(asEdgeVertex[iVertex].fZ);
}
}
}
