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Tim Lawton

DX11 Creating a Font Engine in DirectX11

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Hey there,

I've been trying to create a font engine using Rastertek's guide over at http://rastertek.com/dx11tut12.html

I've come across a problem I can't seem to fix, I've created a struct which holds some data which is used to find the location and size of the font I am using from a image file (a .dds file). It initializes fine, but when it comes to rendering the struct's values are all 0. I'm going to show my font class and say whats going on, you can reference it all back from the tutorial linked above.

If anyone who is experienced in DirectX11 could see a solution to this problem I'd be grateful Also the 'fontdata.txt" and "font.dds" are available on that link also

Font.h

//--------------------------------------------------\\
// Font.h under Text class \\
// handles texture for the font \\
//--------------------------------------------------\\
#ifndef _FONT_H
#define _FONT_H
//includes
#include <D3D11.h>
#include <D3DX10math.h>
#include <fstream>
using namespace std;
#include "Texture.h"
//class
class Font
{
private:
struct FontType
{
float left, right;
int size;
};
struct VertexType
{
D3DXVECTOR3 position;
D3DXVECTOR2 texture;
};
public:
Font();
Font(const Font&amp;);
~Font();
bool Init(ID3D11Device*, char*, CHAR*);
void Shutdown();
ID3D11ShaderResourceView* GetTexture();
void BuildVertexArray(void*, char*, float, float);
private:
bool LoadFontData(char*);
void ReleaseFontData();
bool LoadTexture(ID3D11Device*, CHAR*);
void ReleaseTexture();
private:
FontType* fonttype;
Texture* texture;
};
#endif



Font.cpp

//--------------------------------------------------\\
// Font.cpp under Text class \\
// handles texture for the font \\
//--------------------------------------------------\\
#include "Font.h"
Font::Font()
{
fonttype = 0;
texture = 0;
}
Font::Font(const Font&amp; other){}
Font::~Font(){}
bool Font::Init(ID3D11Device* device, char* fontFilename, CHAR* textureFilename)
{
bool result;

//Load in the text file containing the font data.
result = LoadFontData(fontFilename);
if(!result)
{
return false;
}
// Load the texture that has the font characters on it.
result = LoadTexture(device, textureFilename);
if(!result)
{
return false;
}
return true;
}
void Font::Shutdown()
{
//Release the font texture.
ReleaseTexture();
//Release the font data.
ReleaseFontData();
return;
}
bool Font::LoadFontData(char* filename)
{
ifstream fin;
int i;
char temp;
//Create the font spacing buffer
fonttype = new FontType[95];
if(!fonttype)
{
return false;
}
//Read in the font size and spacing between chars
fin.open(filename);
if(fin.fail())
{
return false;
}
//Read in the 95 used ascii characters for text.
for(i=0; i<95; i++)
{
fin.get(temp);
while(temp != ' ')
{
fin.get(temp);
}
fin.get(temp);
while(temp != ' ')
{
fin.get(temp);
}
fin >> fonttype.left;
fin >> fonttype.right;
fin >> fonttype.size;
}
// Close the file.
fin.close();
return true;
}
void Font::ReleaseFontData()
{
// Release the font data array.
if(fonttype)
{
delete [] fonttype;
fonttype = 0;
}
return;
}
bool Font::LoadTexture(ID3D11Device* device, CHAR* filename)
{
bool result;
//Create the texture object.
texture = new Texture;
if(!texture)
{
return false;
}
//Initialize the texture object.
result = texture->Init(device, filename);
if(!result)
{
return false;
}
return true;
}
void Font::ReleaseTexture()
{
//Release the texture object.
if(texture)
{
texture->Shutdown();
delete texture;
texture = 0;
}
return;
}
ID3D11ShaderResourceView* Font::GetTexture()
{
return texture->GetTexture();
}
void Font::BuildVertexArray(void* vertices, char* sentence, float drawX, float drawY)
{
VertexType* vertexPtr;
int numLetters, index, i, letter;

// Coerce the input vertices into a VertexType structure.
vertexPtr = (VertexType*)vertices;
// Get the number of letters in the sentence.
numLetters = (int)strlen(sentence);
// Initialize the index to the vertex array.
index = 0;
// Draw each letter onto a quad.
for(i=0; i<numLetters; i++)
{
letter = ((int)sentence) - 32;
// If the letter is a space then just move over three pixels.
if(letter == 0)
{
drawX = drawX + 3.0f;
}
else
{
// First triangle in quad.
vertexPtr[index].position = D3DXVECTOR3(drawX, drawY, 0.0f); // Top left.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].left, 0.0f);
index++;
vertexPtr[index].position = D3DXVECTOR3((drawX + fonttype[letter].size), (drawY - 16), 0.0f); // Bottom right.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].right, 1.0f);
index++;
vertexPtr[index].position = D3DXVECTOR3(drawX, (drawY - 16), 0.0f); // Bottom left.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].left, 1.0f);
index++;
// Second triangle in quad.
vertexPtr[index].position = D3DXVECTOR3(drawX, drawY, 0.0f); // Top left.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].left, 0.0f);
index++;
vertexPtr[index].position = D3DXVECTOR3(drawX + fonttype[letter].size, drawY, 0.0f); // Top right.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].right, 0.0f);
index++;
vertexPtr[index].position = D3DXVECTOR3((drawX + fonttype[letter].size), (drawY - 16), 0.0f); // Bottom right.
vertexPtr[index].texture = D3DXVECTOR2(fonttype[letter].right, 1.0f);
index++;
// Update the x location for drawing by the size of the letter and one pixel.
drawX = drawX + fonttype[letter].size + 1.0f;
}
}
return;
}


During the while loop that fills up the array, it starts to store the data. But when it gets to 'drawX = drawX + fonttype[letter].size + 1.0f;' the fonttype array is empty, and stores all 0s for left, right and size.

Any ideas?

EDIT:

to get a better understanding of what I mean, you can see here the fonttype is holding values:
http://img651.imageshack.us/img651/9278/fonttypefilled.png

But at the end of the method it is empty:
http://img715.imageshack.us/img715/3660/fonttypeempty.png

I'm stumped Edited by Xuchilbara

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I'm sorry I can't help you with your exact problem, here are my two cents on fonts and DirectX

1. Drawing 2-D fonts is the responsibility of the OS and you can leverage all that goodness using GDI with offscreen DC or using D2D. No need to wrap or create anything in DX11. We are spoiled because DX9 fonts could also do 2-d fonts but ....
2. The main reason of a DX font is to be a 3-d font which can be rotated and lit with pixel shaders. This is what DX9 font was originally intended for in my opinion, and I've seen people use it for that purpose to good effect.

Going forwards ...

If you need to create 3-d meshes to represent letters of an alphabet, you can either do it offline mathematically with the old DX9 font routines and save the mesh to a file format and read it in DX11 and use it .... or you can have your art team generate these meshes and bring them into the game through normal content pipeline.

All 2-d fonts should be done with D2D or GDI. If you need to get them into 3-d space, you can either use project/unproject to convert a 3-d world position into a 2-d (x,y) point or place a billboard in 3-d space and then write the font using 2-d APIs onto a texture and map it to the billboard. Edited by Steve_Segreto

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Yeah, I know that way of doing it, you mean by making an adapter and linking it with the swap chain, allowing to use DirectX9 or 10. Then using their functions to create font. Although I am not trying to create 3D font, or anything fancy. I am trying to create 2D font which can hold values, such as FPS or mouse position. I can't figure out why the values of my struct almost disappear for no reason, really bumming me out

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I don't think the values disappear, I rather suspect they were not there in the first place.

The code looks semantically the same like rasterteks, so the problems lies probably elsewhere. The debug values -842150451 and -4.3160208E+08 are 0xCDCDCDCD in hex, which is a well known magic [strike]word[/strike]number from the visual studio C++ debug runtime, marking uninitialized heap memory.

I guess your not really loading that glyph description file (wrong path ?) in LoadFontData. Either that or you corrupt your heap elsewhere.

Edit: Hmmm, scratch that, I wasn't looking closely enough. Looks like the >> parsing fails for some reason. Check the state of the of the stream after parsing each value. Edited by unbird

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You mean during this for loop?


//Read in the 95 used ascii characters for text.
for(i=0; i<95; i++)
{
fin.get(temp);
while(temp != ' ')
{
fin.get(temp);
}
fin.get(temp);
while(temp != ' ')
{
fin.get(temp);
}
fin >> fonttype.left;
fin >> fonttype.right;
fin >> fonttype.size;
}


Everythings to be going fine within it

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Really confusing. If the values get parsed just fine, I don't see a reason why they should change afterwards. Nothing else writes to it. At least not in the code you have provided so far (it looks like the original code after all). We need to see more code then.

If you got a professional version of Visual Studio, I think there's a debugger option to break on (specific) memory write or something. Alternatively, grab the raw pointer value after init, add it as a watch (dereferenced), step through your whole frame code and find out when it changes. Or do a comment/uncomment "binary search".

... wait: Is really the whole array filled with zeroes or just the first entry ? Edited by unbird

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Ok, I was wrong about it reading it in correctly.

As you can see here by this screenshot: http://img29.imageshack.us/img29/4099/41977412.jpg

i = 5, thus being 6th in the series. the 6th line in fontdata.txt reads: "37 % 0.0205078 0.0302734 10"
so left should be: 0.0205078
right: 0.0302734
size: 10

Although you can see it is all 0.

Sorry I dont know why I said it was working correctly during the for loop, it must of came up with some magic numbers again at some point and I wasn't paying attention. But yeah I can confirm it is constantly 0, not just the first entry.

Somebody suggested that left and right are floats, and shouldn't be able to take in numbers this long, could that be the case?

Edit: I just tried a breakpoint inside my Init function and something strange came up
http://img41.imageshack.us/img41/553/errorlja.jpg Edited by Xuchilbara

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It's pretty easy, Link the library to your project, Call following functions:

IFW1Factory *pFW1Factory;
HRESULT hResult = FW1CreateFactory(FW1_VERSION, &pFW1Factory);
if(FAILED(hResult)) {
return;
}

hResult = pFW1Factory->CreateFontWrapper(pDevice, _T("ARIAL"), &pFontWrapper);
if(FAILED(hResult)) {
return;
}

....
and to draw some text:

pFontWrapper->DrawString(pDeviceContext,_T("HELLO"),FontSize,PositionX,PositionY,Color,FW1_LEFT | FW1_TOP);


Just don't call the creation functions every time you draw text.

Best regards!

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