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Add tile flange and skirt
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Tile flange solves visual discontinuity between tiles. This was caused
by edge normal computation that had no knowledge of neighbour-tile
geometry. After normal computation, flange is folded to act as a skirt
to plug holes caused by different resolution neighbour tiles.
Caveats:
-Part of texture is wasted on flange/skirt, but also solves texture-edge
problem
-Skirt has flange normals
-Still discontinuitys caused by different resolution neighbouring tiles
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@latami
latami committed Feb 6, 2017
1 parent 48f4e91 commit abf7e08
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Showing 2 changed files with 94 additions and 43 deletions.
127 changes: 85 additions & 42 deletions HeightMap.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,18 @@ HeightMap::HeightMap(unsigned int size,
Ogre::Vector2 LowerRight,
ResourceParameter *param,
Ogre::Real Height_sea)
: Grid(size, face, UpperLeft, LowerRight)
/* Resize by 2 iterations per dimension to include flange */
: Grid(size+2, face,
UpperLeft+Ogre::Vector2(-(LowerRight.x-UpperLeft.x),
-(LowerRight.y-UpperLeft.y))/(size-1),
LowerRight+Ogre::Vector2((LowerRight.x-UpperLeft.x),
(LowerRight.y-UpperLeft.y))/(size-1))
{
/* Save tile dimensions */
this->cornerULeft = UpperLeft;
this->cornerLRight = LowerRight;
this->cornerGSize = size;

Ogre::Real maxAmplitude=0;

child[0] = NULL;
Expand Down Expand Up @@ -83,29 +93,30 @@ void HeightMap::setHeight(unsigned int x, unsigned int y, float elevation)
}

/* Return vector for a normalized (radius 1.0) sphere */
Ogre::Vector3 HeightMap::projectToSphere(unsigned int x, unsigned int y)
Ogre::Vector3 HeightMap::projectToSphere(unsigned int x, unsigned int y,
float elevation)
{
Ogre::Vector3 pos;

// project heightMap to unit sphere by calling parent-class function
pos = Grid::projectToSphere(x, y);
/* add height */
pos = pos + pos*height[y][x];
pos = pos + pos*elevation;
return pos;
}

// scalingFactor scales size of the mesh
void HeightMap::generateMeshData(float scalingFactor)
{
unsigned int x, y, idx;
unsigned int x, y, idx;

idx = 0;
for(x=0; x < gridSize; x++)
{
for(y=0; y < gridSize; y++)
{
// Project height-map location to a sphere
vertexes[idx] = projectToSphere(x, y) * scalingFactor;
vertexes[idx] = projectToSphere(x, y, height[y][x]) * scalingFactor;

// Flatten vertices that are under sea-level
if (vertexes[idx].length() < (1.0f+seaHeight)*scalingFactor)
Expand Down Expand Up @@ -147,6 +158,8 @@ void HeightMap::generateMeshData(float scalingFactor)

// Generate normals
calculateNormals();

foldSkirts(scalingFactor);
}

void HeightMap::calculateNormals()
Expand Down Expand Up @@ -182,13 +195,43 @@ void HeightMap::calculateNormals()
}
}

void HeightMap::foldSkirts(float scaling)
{
Ogre::uint32 x=0, y=0, gSize;
Ogre::Real xProj, yProj;

gSize = this->gridSize;
for(x=0; x < gSize; x++)
{
y=0;
xProj = x;
if (x==0)
xProj = x+1;
else if (x==gSize-1)
xProj = x-1;

/* Cases x=first and x=last */
if ( (x==0) || (x == gSize-1) )
{
for(y=1; y < gSize-1; y++)
{
yProj = y;
vertexes[x*gSize+y] = projectToSphere(xProj, yProj, this->minHeight) * scaling;
}
}
/* vertexes y=first and y=last */
vertexes[x*gSize+0] = projectToSphere(xProj, 1, this->minHeight) * scaling;
vertexes[x*gSize+gSize-1] = projectToSphere(xProj, gSize-2, this->minHeight) * scaling;
}
}

void HeightMap::createGeometry()
{
Ogre::uint16 x, y, gSize;
Ogre::Real elev;
Ogre::Vector3 spherePos;

gSize = this->getSize();
gSize = this->gridSize;
for(y=0; y < gSize; y++)
{
for(x=0; x < gSize; x++)
Expand Down Expand Up @@ -352,43 +395,43 @@ Ogre::AxisAlignedBox HeightMap::tileAABox(void)
Ogre::Vector3 corner[9], max, min;

// Upper left with positive height
corner[0].x = this->UpperLeft.x;
corner[0].x = this->cornerULeft.x;
corner[0].y = this->maxHeight+1.0f;
corner[0].z = this->UpperLeft.y;
corner[0].z = this->cornerULeft.y;
//Upper left with minimum height
corner[1].x = this->UpperLeft.x;
corner[1].x = this->cornerULeft.x;
corner[1].y = this->minHeight+1.0f;
corner[1].z = this->UpperLeft.y;
corner[1].z = this->cornerULeft.y;
// Upper right
corner[2].x = this->LowerRight.x;
corner[2].x = this->cornerLRight.x;
corner[2].y = this->maxHeight+1.0f;
corner[2].z = this->UpperLeft.y;
corner[2].z = this->cornerULeft.y;

corner[3].x = this->LowerRight.x;
corner[3].x = this->cornerLRight.x;
corner[3].y = this->minHeight+1.0f;
corner[3].z = this->UpperLeft.y;
corner[3].z = this->cornerULeft.y;
// Lower left
corner[4].x = this->UpperLeft.x;
corner[4].x = this->cornerULeft.x;
corner[4].y = this->maxHeight+1.0f;
corner[4].z = this->LowerRight.y;
corner[4].z = this->cornerLRight.y;

corner[5].x = this->UpperLeft.x;
corner[5].x = this->cornerULeft.x;
corner[5].y = this->minHeight+1.0f;
corner[5].z = this->LowerRight.y;
corner[5].z = this->cornerLRight.y;
// Lower right
corner[6].x = this->LowerRight.x;
corner[6].x = this->cornerLRight.x;
corner[6].y = this->maxHeight+1.0f;
corner[6].z = this->LowerRight.y;
corner[6].z = this->cornerLRight.y;

corner[7].x = this->LowerRight.x;
corner[7].x = this->cornerLRight.x;
corner[7].y = this->minHeight+1.0f;
corner[7].z = this->LowerRight.y;
corner[7].z = this->cornerLRight.y;

/* Tile center protrudes considerably (especially with full face), so add
* it as one of the corners. */
corner[8].x = (this->UpperLeft.x + this->LowerRight.x)/2.0f;
corner[8].x = (this->cornerULeft.x + this->cornerLRight.x)/2.0f;
corner[8].y = this->maxHeight+1.0f;
corner[8].z = (this->UpperLeft.y + this->LowerRight.y)/2.0f;
corner[8].z = (this->cornerULeft.y + this->cornerLRight.y)/2.0f;

// Rotate and scale
for(int i=0; i < 9; i++)
Expand Down Expand Up @@ -540,25 +583,25 @@ bool HeightMap::createChildren()
{
Ogre::Vector2 upperL, lowerR;

upperL = this->UpperLeft;
lowerR = upperL + (this->LowerRight-this->UpperLeft)/2.0f;
this->child[0] = new HeightMap(this->gridSize, this->orientation, upperL,
upperL = this->cornerULeft;
lowerR = upperL + (this->cornerLRight-this->cornerULeft)/2.0f;
this->child[0] = new HeightMap(this->cornerGSize, this->orientation, upperL,
lowerR, this->RParam, this->seaHeight);

upperL.x += (this->LowerRight.x-this->UpperLeft.x)/2.0f;
lowerR.x += (this->LowerRight.x-this->UpperLeft.x)/2.0f;
this->child[1] = new HeightMap(this->gridSize, this->orientation, upperL,
upperL.x += (this->cornerLRight.x-this->cornerULeft.x)/2.0f;
lowerR.x += (this->cornerLRight.x-this->cornerULeft.x)/2.0f;
this->child[1] = new HeightMap(this->cornerGSize, this->orientation, upperL,
lowerR, this->RParam, this->seaHeight);

upperL = this->UpperLeft;
upperL.y += (this->LowerRight.y-this->UpperLeft.y)/2.0f;
lowerR = upperL + (this->LowerRight-this->UpperLeft)/2.0f;
this->child[2] = new HeightMap(this->gridSize, this->orientation, upperL,
upperL = this->cornerULeft;
upperL.y += (this->cornerLRight.y-this->cornerULeft.y)/2.0f;
lowerR = upperL + (this->cornerLRight-this->cornerULeft)/2.0f;
this->child[2] = new HeightMap(this->cornerGSize, this->orientation, upperL,
lowerR, this->RParam, this->seaHeight);

upperL.x += (this->LowerRight.x-this->UpperLeft.x)/2.0f;
lowerR.x += (this->LowerRight.x-this->UpperLeft.x)/2.0f;
this->child[3] = new HeightMap(this->gridSize, this->orientation, upperL,
upperL.x += (this->cornerLRight.x-this->cornerULeft.x)/2.0f;
lowerR.x += (this->cornerLRight.x-this->cornerULeft.x)/2.0f;
this->child[3] = new HeightMap(this->cornerGSize, this->orientation, upperL,
lowerR, this->RParam, this->seaHeight);
}

Expand Down Expand Up @@ -618,7 +661,7 @@ Ogre::Vector3 HeightMap::getCenterPosition()
Ogre::Vector2 tileCenter;
Ogre::Vector3 pos;

tileCenter = (this->UpperLeft + this->LowerRight)/2.0f;
tileCenter = (this->cornerULeft + this->cornerLRight)/2.0f;
pos = Ogre::Vector3(tileCenter.x, 1.0f, tileCenter.y).normalisedCopy();

return this->orientation*pos*RParam->getRadius();
Expand All @@ -635,19 +678,19 @@ bool HeightMap::isLoaded()
void HeightMap::getCornerPosition(Ogre::Vector3 &upperLeft, Ogre::Vector3 &upperRight,
Ogre::Vector3 &lowerLeft, Ogre::Vector3 &lowerRight)
{
upperLeft = Ogre::Vector3(this->UpperLeft.x, 1.0f, this->UpperLeft.y);
upperLeft = Ogre::Vector3(this->cornerULeft.x, 1.0f, this->cornerULeft.y);
upperLeft.normalise();
upperLeft = this->orientation*upperLeft*RParam->getRadius();

upperRight = Ogre::Vector3(this->LowerRight.x, 1.0f, this->UpperLeft.y);
upperRight = Ogre::Vector3(this->cornerLRight.x, 1.0f, this->cornerULeft.y);
upperRight.normalise();
upperRight = this->orientation*upperRight*RParam->getRadius();

lowerLeft = Ogre::Vector3(this->UpperLeft.x, 1.0f, this->LowerRight.y);
lowerLeft = Ogre::Vector3(this->cornerULeft.x, 1.0f, this->cornerLRight.y);
lowerLeft.normalise();
lowerLeft = this->orientation*lowerLeft*RParam->getRadius();

lowerRight = Ogre::Vector3(this->LowerRight.x, 1.0f, this->LowerRight.y);
lowerRight = Ogre::Vector3(this->cornerLRight.x, 1.0f, this->cornerLRight.y);
lowerRight.normalise();
lowerRight = this->orientation*lowerRight*RParam->getRadius();
}
Expand Down
10 changes: 9 additions & 1 deletion HeightMap.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ class HeightMap: public Grid
Ogre::Real Height_sea);
~HeightMap();
void setHeight(unsigned int x, unsigned int y, float elevation);
Ogre::Vector3 projectToSphere(unsigned int x, unsigned int y);
Ogre::Vector3 projectToSphere(unsigned int x, unsigned int y, float elevation);

/* Fills hardware-buffers with vertice- and texture-data. Creates entity
* called Name, mesh called Name+"_mesh", material called Name+"_material",
Expand Down Expand Up @@ -85,6 +85,11 @@ class HeightMap: public Grid

HeightMap *child[4];

/* Tile dimensions without flange/skirt */
Ogre::Vector2 cornerULeft;
Ogre::Vector2 cornerLRight;
Ogre::uint32 cornerGSize;

Ogre::Vector3 *vertexes;
Ogre::Vector3 *verNorms;
Ogre::Vector2 *txCoords;
Expand All @@ -95,6 +100,9 @@ class HeightMap: public Grid

void calculateNormals();

/* Fold tile flanges into skirts */
void foldSkirts(float scaling);

/* Creates vertex-data and indexes */
void generateMeshData(float scalingFactor);

Expand Down

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