float kit::BakedTerrain::sampleHeight(float x, float z)
{
glm::vec2 fullSize;
fullSize.x = float(m_size.x) * m_xzScale;
fullSize.y = float(m_size.y) * m_xzScale;
glm::vec2 halfSize = fullSize / 2.0f;
x += halfSize.x;
z += halfSize.y;
float xMap = x / m_xzScale;
float zMap = z / m_xzScale;
uint32_t px = (uint32_t)glm::floor(xMap);
uint32_t pz = (uint32_t)glm::floor(zMap);
uint32_t hx = px + 1;
uint32_t hz = pz + 1;
float v1 = getVertexAt(px, pz).m_height;
float v2 = getVertexAt(hx, pz).m_height;
float v3 = getVertexAt(px, hz).m_height;
float v4 = getVertexAt(hx, hz).m_height;
// Calculate the weights for each pixel
float fx = (xMap - (float)px);
float fz = (zMap - (float)pz);
float fx1 = 1.0f - fx;
float fz1 = 1.0f - fz;
float w1 = fx1 * fz1;
float w2 = fx * fz1;
float w3 = fx1 * fz;
float w4 = fx * fz;
float height = v1 * w1 + v2 * w2 + v3 * w3 + v4 * w4;
//std::cout << "Height at " << x << "x" << z << ": " << height << std::endl;
return height * m_yScale;
}
glm::vec3 kit::BakedTerrain::sampleNormal(float x, float z)
{
glm::vec2 fullSize;
fullSize.x = float(m_size.x) * m_xzScale;
fullSize.y = float(m_size.y) * m_xzScale;
glm::vec2 halfSize = fullSize / 2.0f;
x += halfSize.x;
z += halfSize.y;
float xMap = x / m_xzScale;
float zMap = z / m_xzScale;
uint32_t px = (uint32_t)glm::floor(xMap);
uint32_t pz = (uint32_t)glm::floor(zMap);
uint32_t hx = px + 1;
uint32_t hz = pz + 1;
glm::vec3 v1 = getVertexAt(px, pz).m_normal;
glm::vec3 v2 = getVertexAt(hx, pz).m_normal;
glm::vec3 v3 = getVertexAt(px, hz).m_normal;
glm::vec3 v4 = getVertexAt(hx, hz).m_normal;
// Calculate the weights for each pixel
float fx = (xMap - (float)px);
float fz = (zMap - (float)pz);
float fx1 = 1.0f - fx;
float fz1 = 1.0f - fz;
float w1 = fx1 * fz1;
float w2 = fx * fz1;
float w3 = fx1 * fz;
float w4 = fx * fz;
glm::vec3 normal = v1 * w1 + v2 * w2 + v3 * w3 + v4 * w4;
return normal;
}
/*
* Use 5 tetraherons to triangulate isosurface in cell
* Fill vertices, indices and normals
*/
void CTdata::triangulateCell5(int x, int y, int z, float isovalue)
{
const int * tetrahedraIds;
// which type of tetrahedra split...
if ((((x/stepX)%2)*2-1)*(((y/stepY)%2)*2-1)*(((z/stepZ)%2)*2-1)<0){
// type A
tetrahedraIds = tetrahedron5a;
} else {
// type B
tetrahedraIds = tetrahedron5b;
}
// cell points
Vertex* cellVertices[8];
cellVertices[0] = & getVertexAt(x , y , z );
cellVertices[1] = & getVertexAt(x+1, y , z );
cellVertices[2] = & getVertexAt(x+1, y+1, z );
cellVertices[3] = & getVertexAt(x , y+1, z );
cellVertices[4] = & getVertexAt(x , y , z+1);
cellVertices[5] = & getVertexAt(x+1, y , z+1);
cellVertices[6] = & getVertexAt(x+1, y+1, z+1);
cellVertices[7] = & getVertexAt(x , y+1, z+1);
int i, j;
char type;
// select tetrahedra vertices
Vertex* tetrahedraVertices[4];
for (i=0; i<5; i++){
type = 0;
for (j=0; j<4; j++){
tetrahedraVertices[j] = cellVertices[tetrahedraIds[i*4+j]];
if (tetrahedraVertices[j]->value>=isovalue){
type+=powersOf2[j];
}
}
// do some funny stuff with tetrahedraVertices...
/*
_-0-_
_- | -_
3 - -|- - 1
\ | /
\ | /
\ | /
\|/
2
README:
- dvojice pøípadù se liší jen opaènou orientací roviny. Proto se
pro nìkteré nastavuje flipFlag na true - ty se musí otoèit obrácenì
- je tøeba produkovat trojúhelníky a to i pro pøípad,
kdy se má vytvoøit 4 úhelník (tedy rozdìlit na dva trojúhelníky)
TODO : Takto produkovaná struktura by mìla redundantní body.
Vìtšina bodù je sdílená více trojúhelníky. Lze s výhodou využít ELEMENT_DRAW.
proto je NUTNÉ pøedìlat uložištì bodù na nìco jako MAP a nepøidávat tam tedy bod,
který má stejné souøadnice!!!
*/
Vertex v1, v2, v3, v4;
bool flipFlag = true;
switch (type){
case 0:
case 15:
// no intersection
break;
case 1:
flipFlag = false;
case 14:
// intersection with 3 edges from pt 0
v1 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[1], isovalue);
v2 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[2], isovalue);
v3 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[3], isovalue);
if (flipFlag) {
push(v3, v2, v1);
} else {
push(v1, v2, v3);
}
break;
case 2:
flipFlag = false;
case 13:
// intersection with 3 edges from pt 1
v1 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[0], isovalue);
v2 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[2], isovalue);
v3 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[3], isovalue);
if (flipFlag) {
push(v1, v2, v3);
} else {
push(v1, v3, v2);
}
break;
case 4:
flipFlag = false;
case 11:
// intersection with 3 edges from pt 2
v1 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[0], isovalue);
v2 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[1], isovalue);
v3 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[3], isovalue);
if (flipFlag) {
push(v1, v3, v2);
} else {
push(v1, v2, v3);
}
break;
case 8:
flipFlag = false;
case 7:
// intersection with 3 edges from pt 3
v1 = interpolate(*tetrahedraVertices[3], *tetrahedraVertices[0], isovalue);
v2 = interpolate(*tetrahedraVertices[3], *tetrahedraVertices[1], isovalue);
v3 = interpolate(*tetrahedraVertices[3], *tetrahedraVertices[2], isovalue);
if (flipFlag) {
push(v1, v2, v3);
} else {
push(v1, v3, v2);
}
break;
case 3:
flipFlag = false;
case 12:
// intersection with 4 edges
v1 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[2], isovalue);
v2 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[3], isovalue);
v3 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[3], isovalue);
v4 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[2], isovalue);
if (flipFlag) {
push(v1, v3, v2);
push(v1, v4, v3);
} else {
push(v1, v2, v3);
push(v1, v3, v4);
}
break;
case 5:
flipFlag = false;
case 10:
// intersection with 4 edges
v1 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[1], isovalue);
v2 = interpolate(*tetrahedraVertices[0], *tetrahedraVertices[3], isovalue);
v3 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[3], isovalue);
v4 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[1], isovalue);
if (flipFlag) {
push(v1, v2, v3);
push(v1, v3, v4);
} else {
push(v1, v3, v2);
push(v1, v4, v3);
}
break;
case 6:
flipFlag = false;
case 9:
// intersection with 4 edges
v1 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[0], isovalue);
v2 = interpolate(*tetrahedraVertices[1], *tetrahedraVertices[3], isovalue);
v3 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[3], isovalue);
v4 = interpolate(*tetrahedraVertices[2], *tetrahedraVertices[0], isovalue);
if (flipFlag) {
push(v2, v4, v3);
push(v4, v2, v1);
} else {
push(v4, v2, v3);
push(v2, v4, v1);
}
break;
}
} // next tetrahedra...
}
