// Find a place to pack a bitmap into a larger bitmap
BinPackNode *BinPack(BMSize BitmapWidth, BMSize BitmapHeight, BinPackNode *ParentNode)
{
// This function is copied almost exactly from: http://www.blackpawn.com/texts/lightmaps/
if(ParentNode->Children[0] != nullptr || ParentNode->Children[1] != nullptr)
{
// Try inserting into first child
BinPackNode *newNode = BinPack(BitmapWidth, BitmapHeight, ParentNode->Children[0].get());
if(newNode != nullptr)
return newNode;
// No room in first child, try inserting into second
return BinPack(BitmapWidth, BitmapHeight, ParentNode->Children[1].get());
}
else
{
// Check if there is already a glyph here
if(ParentNode->Filled)
return nullptr;
// Check if the glyph is too big to fit in this node
if(ParentNode->Rect.z < BitmapWidth || ParentNode->Rect.w < BitmapHeight)
return nullptr;
// Check if the glyph fits perfectly in this node
if(ParentNode->Rect.z == BitmapWidth && ParentNode->Rect.w == BitmapHeight)
{
ParentNode->Filled = true;
return ParentNode;
}
// Node is larger than the glyph, so split the node into two
ParentNode->Children[0].reset(new BinPackNode());
ParentNode->Children[1].reset(new BinPackNode());
// Decide which way to split
int SpaceWidth = ParentNode->Rect.z - BitmapWidth;
int SpaceHeight = ParentNode->Rect.w - BitmapHeight;
if(SpaceWidth > SpaceHeight)
{
ParentNode->Children[0]->Rect = vec4(ParentNode->Rect.x, ParentNode->Rect.y, BitmapWidth, ParentNode->Rect.w);
ParentNode->Children[1]->Rect = vec4(ParentNode->Rect.x + BitmapWidth, ParentNode->Rect.y, SpaceWidth, ParentNode->Rect.w);
}
else
{
ParentNode->Children[0]->Rect = vec4(ParentNode->Rect.x, ParentNode->Rect.y, ParentNode->Rect.z, BitmapHeight);
ParentNode->Children[1]->Rect = vec4(ParentNode->Rect.x, ParentNode->Rect.y + BitmapHeight, ParentNode->Rect.z, SpaceHeight);
}
// Insert into first child
return BinPack(BitmapWidth, BitmapHeight, ParentNode->Children[0].get());
}
}
bool Font::CreateAtlas()
{
unsigned int totalPixels = 0;
for (FontSymbols::const_iterator it = this->symbols.cbegin(), end = this->symbols.cend(); it != end; ++it)
{
std::shared_ptr<FontSymbol> glyph = it->second;
totalPixels += glyph->GetPixelCount();
}
unsigned int textureWidth = 1;
unsigned int textureHeight = 1;
while (textureWidth * textureHeight < totalPixels)
{
if (textureWidth < textureHeight)
{
textureWidth *= 2;
}
else
{
textureHeight *= 2;
}
if (textureWidth > MaxTextureDimension || textureHeight > MaxTextureDimension)
{
LogError("Font atlas became too large.");
return false;
}
}
std::vector<std::shared_ptr<FontSymbol>> sortedSymbols;
for (FontSymbols::const_iterator it = this->symbols.cbegin(), end = this->symbols.cend(); it != end; ++it)
{
sortedSymbols.push_back(it->second);
}
std::sort(sortedSymbols.begin(), sortedSymbols.end(),
[](std::shared_ptr<FontSymbol> &glyph1, std::shared_ptr<FontSymbol> &glyph2) -> bool {
return glyph1->GetPixelCount() > glyph2->GetPixelCount();
}
);
GlyphTreeNode::GetAllocator().Init((this->symbols.size() + 1) * 2);
if (!BinPack(textureWidth, textureHeight))
{
// TODO: We shouldn't fail like this because binary packing the glyphs might fail if for example
// texture is not big enough to fit all glyphs because of too many unused gaps. In such case we should
// continue looping and increase textureWidth & textureHeight until BinPack succeeds.
GlyphTreeNode::GetAllocator().Release();
LogError("Font::BinPack has failed.");
return false;
}
GlyphTreeNode::GetAllocator().Release();
unsigned char *textureBuffer = new unsigned char[textureWidth * textureHeight];
for (FontSymbols::const_iterator it = this->symbols.cbegin(), end = this->symbols.cend(); it != end; ++it)
{
std::shared_ptr<FontSymbol> symbol = it->second;
symbol->RenderToBuffer(textureBuffer, textureWidth, textureHeight);
symbol->GlyphLoaded();
}
glGenTextures(1, &this->glTexture);
glBindTexture(GL_TEXTURE_2D, this->glTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, textureWidth, textureHeight, 0, GL_ALPHA, GL_UNSIGNED_BYTE, textureBuffer);
GL_CHECK_ERROR();
delete[] textureBuffer;
this->atlas = std::shared_ptr<FontSymbol>(TG_NEW FontSymbol);
this->atlas->SetXY(0, 0);
this->atlas->SetSize(textureWidth, textureHeight);
this->atlas->InitTextureCoords(textureWidth, textureHeight);
return true;
}
