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OpenGL FreeType troubles...

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I am having a really harsh time in trying to implement Font rendering into my Engine... Now I'm mainly getting pissed off with FreeType, I just can't seem to understand it 100%. I'm loading the Font with TrueType and then looping through all the glyphs in the font and saving them into one single big Texture, in ASCII order, and uploading them to OpenGL, but that's not working out so well.

I would really appreciate it if someone looked at my code and explain to me what I am doing wrong. At the moment I can't load a TrueType font and I doubt I'm rendering them correctly either but I am not sure as I have not tested it...

Here is how I am loading fonts; the maximum size of a font is defaulted to 20, to save into a Texture:
void OGLGraphicalAssetLoader::loadFontFromFile(const std::string& filepath, Font* output) const
{
FT_Library library; // a FreeType Library object
FT_Face face; // This holds the TrueType Font.
FT_Error error; // Holds any errors that could occur.
error = FT_Init_FreeType(&library); // Initialize the FreeType Library
if(error)
{
throw AnaxException("FreeType 2 Library could not be initialized", -2);
}
// Load the TrueType Font into memory
error = FT_New_Face(library, filepath.c_str(), 0, &face);
if(error)
{
throw AnaxException("Could not load TrueType Font: " + filepath, -2);
}
FT_Set_Char_Size(face, output->getMaxSize() * 64, output->getMaxSize() * 64, 96, 96); // Set the size of the Font

// Create a blank Texture (Image)
Image tempImage;
tempImage.create(face->glyph->bitmap.width, face->glyph->bitmap.rows);

Rect2DFloat textureCoords; // Holds temporary Texture Coordinates
Uint32 drawX = 0, drawY = 0; // The x and y coordinates that the glypth will be drawn to in the Texture.
// Loop through the Glyph's putting them in the Texture (Image)
for(int i = 0; i < 256; ++i)
{
Uint32 index = FT_Get_Char_Index(face, (char)i);
error = FT_Load_Glyph(face, index, FT_LOAD_DEFAULT);
if(error)
continue; // just ignore it.. (should throw an except or something along those lines
error = FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
if(error)
continue; // just ignore it...

// Place Texture Coordinates
textureCoords.position.x = drawX + face->glyph->bitmap_left;
textureCoords.position.y = drawY - face->glyph->bitmap_top;
textureCoords.size.width = face->glyph->bitmap.width;
textureCoords.size.height = face->glyph->bitmap.rows;
setFontTextureCoordinateValueForGlyth(output, i, textureCoords); // Set the Texture Coordinates
// Render into Image
BlitGlypth(face->glyph, &tempImage, textureCoords.position.x, textureCoords.position.y);

// Increment drawing position
drawX += face->glyph->advance.x >> 6;
drawY += face->glyph->advance.y >> 6;
}
// Upload the Texture to OpenGL
Texture2D tempTexture;
loadTextureFromImage(tempImage, &tempTexture);
// Set the ID of the Font
setFontIdNumber(output, tempTexture.getID());
}



I'm not quite sure if I'm formatting each character correctly into my texture, also I do not know how to get or calculate the size that the Texture will be. When I am calling tempImage.create() it parses 0, 0 for the dimensions of the image... S:? Is it because there is not current glyph selected or..? How do I calculate what the Texture size should be.

Here is how I am drawing the Font's, using a Rectangle to draw them:

void OGLRenderer::renderText(const Renderable2DText& text)
{
const std::string& theCharactersToRender = text.getText();
Renderable2DRect& rect = getRectFromText(text);

// Loop through all the characters
for(int i = 0; i < theCharactersToRender.length(); ++i)
{
const Rect2DFloat& subRect = text.getFont()->getGlypth(i);
rect.setSubRect(subRect);

// Render the Rect
renderRect(rect);
rect.move(subRect.position.x, subRect.position.y);
}
}


If you need anymore detail on how I am implementing this, please say so :)

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[font=arial,helvetica,sans-serif]Ahh i remember having this problem myself. It had something to do with [color=#000000]

FT_Set_Char_Size and the glyph methods (ft 2.4.4). I couldnt figure out what it was so i changed using those by using

[/font]FT_Set_Pixel_Sizes and FT_Load_Char instead. Here's what i got so you can take a look at how that works:

FontLoader::FontLoader() :
logger( Logger::Instance() )
{
FT_Error error = FT_Init_FreeType( &library );
if ( error )
logger.Print( LOGGERDEPTH_CONSTRUCTOR, LOGGERSCOPE_NOCHANGE, "cn", "Font loader could not be initialized." );
logger.Print( LOGGERDEPTH_CONSTRUCTOR, LOGGERSCOPE_NOCHANGE, "cn", "ResourceLoaderFont created." );
}
FontLoader::~FontLoader()
{
logger.Print( LOGGERDEPTH_DESTRUCTOR, LOGGERSCOPE_NOCHANGE, "cn", "ResourceLoaderFont destroyed." );
}
EEResource::Font* FontLoader::LoadFont( RenderResourceCreator& renderResourceCreator, const std::string& fontFile, uint8 fontSize )
{
FT_Error error;
FT_Face face;
if( error = (FT_New_Face( library, fontFile.c_str(), 0, &face ) ) )
{
if ( error == FT_Err_Unknown_File_Format )
logger.Print( LOGGERDEPTH_WARNING, LOGGERSCOPE_NOCHANGE, "mcscn", __FUNCTION__, ": Format of font \"", fontFile, "\" is unsupported." );
else
logger.Print( LOGGERDEPTH_WARNING, LOGGERSCOPE_NOCHANGE, "mcscn", __FUNCTION__, ": Font \"", fontFile, "\" could not be opened or read." );
return NULL;
}

//error = FT_Set_Char_Size(
// face, /* handle to face object */
// 0, /* char_width in 1/64th of points */
// 16*64, /* char_height in 1/64th of points */
// 300, /* horizontal device resolution */
// 300 ); /* vertical device resolution */
FT_Set_Pixel_Sizes( face, 0, fontSize );
int textureWidth = 0;
int textureHeight = 0;
EEResource::Font* newFont = new EEResource::Font( fontFile, fontSize );
for( uint16 charIndex = 0; charIndex < 256; ++charIndex )
{
error = FT_Load_Char( face, charIndex, FT_LOAD_RENDER );
Vector2f advance( float( face->glyph->advance.x >> 6 ), float( face->glyph->advance.y >> 6 ) );
uint8 width = face->glyph->bitmap.width;
uint8 height = face->glyph->bitmap.rows;
uint8* data = new uint8[ width * height ];
//Rendered data is upside down so we need to revert that.
for( uint8 row = 0; row < height; ++row )
memcpy( data + width * row, face->glyph->bitmap.buffer + width * (height - row - 1), sizeof( uint8 ) * width );
newFont->SetCharacter( (uint8)charIndex, advance, width, height, face->glyph->bitmap_left, face->glyph->bitmap_top, data );
}

if( !renderResourceCreator.LoadFont( *newFont ) )
{
logger.Print( LOGGERDEPTH_WARNING, LOGGERSCOPE_NOCHANGE, "mcscn", __FUNCTION__, ": Font \"", fontFile, "\" could not be loaded by the renderer." );
delete newFont;
return NULL;
}
else
return newFont;
}


On a side note: i dont think you have to init the library for every font you're loading

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Couple of Questions:
1. Why are you parsing the height instead of the width in this function:

[color=#000000]FT_Set_Pixel_Sizes[color=#666600]([color=#000000] face[color=#666600],[color=#000000] [color=#006666]0[color=#666600],[color=#000000] fontSize [color=#666600]);
i.e. why are you calling it like this?

[color=#000000]FT_Set_Pixel_Sizes[color=#666600]([color=#000000] face[color=#666600],[color=#000000] [color=#000000]fontSize[color=#666600],[color=#000000] [color=#006666]0[color=#666600]);

2. What are you doing with textureWidth and textureHeight?

[color=#000088]int[color=#000000] textureWidth [color=#666600]=[color=#000000] [color=#006666]0[color=#666600];
[color=#000088]int[color=#000000] textureHeight [color=#666600]=[color=#000000] [color=#006666]0[color=#666600];

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1: it doesn't really matter, this is some code that's inside the FT_Set_Pixel_Sizes for the version i'm using:


if ( pixel_width == 0 )
pixel_width = pixel_height;
else if ( pixel_height == 0 )
pixel_height = pixel_width;

so [color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

FT_Set_Pixel_Sizes

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

(

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

[/font][color=#006666][font=helvetica, arial, verdana, tahoma, sans-serif]

0

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

); is the same as

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

FT_Set_Pixel_Sizes

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

(

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize, 0

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

); and

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

FT_Set_Pixel_Sizes

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

(

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

[/font][color=#006666][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,

[/font][color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize

[/font][color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

);

[/font]

2: nothing at all haha. I noticed them sitting around there aswell but i was too lazy to remove them :P. I know when i've started creating the fontloader i tried to put all characters in an as small as possible image but i couldn't really be bothered to finish that because gpu mem isn't an issue right now. So i gues it's just a remnant from that.

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FT_Set_Pixel_Sizes


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

([/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,[/font]


[color=#006666][font=helvetica, arial, verdana, tahoma, sans-serif]

0[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,[/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize [/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

); is the same as [/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

FT_Set_Pixel_Sizes[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

([/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,[/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize, 0 [/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

); and [/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

FT_Set_Pixel_Sizes[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

([/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

face[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,[/font]


[color=#006666][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize[/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

,[/font]


[color=#000000][font=helvetica, arial, verdana, tahoma, sans-serif]

fontSize [/font]


[color=#666600][font=helvetica, arial, verdana, tahoma, sans-serif]

);[/font]




Dont you just looooove auto format.....

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Okay, I'm still having troubles, I have a question and I am not sure what I'm doing wrong o.O...

1. So with the FT_Set_Pixel_Sizes it sets the amount of pixels a glyph in the font should use for it's width/height, correct? Which means I can't have decimal sizes, right?


Here's my Code, it doesn't complain about loading or rendering, but I must be stuffing up somewhere.

Loading the Font:

void OGLGraphicalAssetLoader::loadFontFromFile(const std::string&amp; filepath, Font* output) const
{
FT_Library library; // a FreeType Library object
FT_Face face; // This holds the TrueType Font.

FT_Error error; // Holds any errors that could occur.

error = FT_Init_FreeType(&amp;library); // Initialize the FreeType Library

if(error)
{
throw AnaxException("FreeType 2 Library could not be initialized", -2);
}

// Load the TrueType Font into memory
error = FT_New_Face(library, filepath.c_str(), 0, &amp;face);
if(error)
{
throw AnaxException("Could not load TrueType Font: " + filepath, -2);
}

float maxSize = output->getMaxSize();
float width = maxSize * 64;


// Set the size of the Font
FT_Set_Pixel_Sizes(face, 0, maxSize);

// Create a blank Texture (Image)
Image tempImage;
tempImage.create(maxSize * 256, maxSize * 2);


Rect2DFloat textureCoords; // Holds temporary Texture Coordinates
int drawX = 0, drawY = maxSize; // The x and y coordinates that the glypth will be drawn to in the Texture.


FT_GlyphSlot slot = face->glyph; // The Glyph slot for the face

// Loop through the Glyph's putting them in the Texture (Image)
for(int i = 0; i < 256; ++i)
{
Uint32 index = FT_Get_Char_Index(face, i);

error = FT_Load_Char(face, index, FT_LOAD_RENDER);
if(error)
continue; // just ignore it..


// Place Texture Coordinates
textureCoords.position.x = drawX + slot->bitmap_left;
textureCoords.position.y = drawY - slot->bitmap_top;
textureCoords.size.width = slot->bitmap.width;
textureCoords.size.height = slot->bitmap.rows;

setFontTextureCoordinateValueForGlyth(output, i, textureCoords); // Set the Texture Coordinates

// Render into Image
BlitGlypth(face->glyph, &amp;tempImage, textureCoords.position.x, textureCoords.position.y);


// Increment drawing position
drawX += face->glyph->advance.x >> 6;
}

// Upload the Texture to OpenGL
Texture2D tempTexture;
loadTextureFromImage(tempImage, &amp;tempTexture);

// Set the ID of the Font
setFontTexture(output, tempTexture);
}



Bltting the Glyph to the Image:

void BlitGlypth(const FT_GlyphSlot glypth, Image *output, Uint32 xForOutput, Uint32 yForOutput)
{
Uint32 x, y;
for(y = 0; y < glypth->bitmap.rows; ++y)
{
for(x = 0; x < glypth->bitmap.width; ++x)
{
Uint32 pixel = glypth->bitmap.buffer[(x * glypth->bitmap.width) + y]; // access the pixel
output->setPixel(xForOutput + x, yForOutput + y, Colour(255, 255, 255, pixel)); // place it in the image
}
}
}


Rendering the Font:


void OGLRenderer::renderText(const Renderable2DText&amp; text)
{
const std::string&amp; theCharactersToRender = text.getText();
Renderable2DRect&amp; rect = getRectFromText(text);

float drawX = 0;
float drawY = 0;

char currentChar = 0;

// Loop through all the characters
for(int i = 0; i < theCharactersToRender.length(); ++i)
{
// Update the current character
currentChar = theCharactersToRender;


if(currentChar == '\n')
{
//drawX = 0;
//drawY += subRect.size.height;
}
else if(currentChar == ' ')
{
//drawX += text.getLineSpacing();
}
else
{
const Rect2DFloat&amp; subRect = text.getFont()->getGlypth(currentChar);
rect.setSubRect(subRect);

// Render the Rect
renderRect(rect);

drawX += subRect.size.width + 1;
}


rect.move(drawX, drawY);
}
}


I've noticed that my Font is rendered sideways or something, and it seems to not be in the correct order or something? S: What I mean is: For example the '+' sign (43 in ASCII) is not 43 characters from the NULL character (0). Now I tried rendering the '+' character (adding 28 to it too, to make it render the '+' character) but all I get when I render it (zoomed in, with a rectangle next to it) is this, how do I fix it?
plussign.png


Here is the Image that was generated from the .ttf (the alpha channels might not show in the .png, I'm not sure S:), I don't know how to get the Image width exactly so it's not giving me excess pixels...:
temp0.png

Many thanks in advance.

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You're still using [color=#000000][size=2]

FT_Get_Char_Index, n

ot sure what it does but it has weird results for me aswell, works perfectly fine without though.

[color=#000000]

Your texture coordinate calculation also looks weird but i havn't really looked at it because the output texture seems bollocks to begin with, could you verify it doesnt look this bad on your end?

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      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

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    • By TheChubu
      The Khronos™ Group, an open consortium of leading hardware and software companies, announces from the SIGGRAPH 2017 Conference the immediate public availability of the OpenGL® 4.6 specification. OpenGL 4.6 integrates the functionality of numerous ARB and EXT extensions created by Khronos members AMD, Intel, and NVIDIA into core, including the capability to ingest SPIR-V™ shaders.
      SPIR-V is a Khronos-defined standard intermediate language for parallel compute and graphics, which enables content creators to simplify their shader authoring and management pipelines while providing significant source shading language flexibility. OpenGL 4.6 adds support for ingesting SPIR-V shaders to the core specification, guaranteeing that SPIR-V shaders will be widely supported by OpenGL implementations.
      OpenGL 4.6 adds the functionality of these ARB extensions to OpenGL’s core specification:
      GL_ARB_gl_spirv and GL_ARB_spirv_extensions to standardize SPIR-V support for OpenGL GL_ARB_indirect_parameters and GL_ARB_shader_draw_parameters for reducing the CPU overhead associated with rendering batches of geometry GL_ARB_pipeline_statistics_query and GL_ARB_transform_feedback_overflow_querystandardize OpenGL support for features available in Direct3D GL_ARB_texture_filter_anisotropic (based on GL_EXT_texture_filter_anisotropic) brings previously IP encumbered functionality into OpenGL to improve the visual quality of textured scenes GL_ARB_polygon_offset_clamp (based on GL_EXT_polygon_offset_clamp) suppresses a common visual artifact known as a “light leak” associated with rendering shadows GL_ARB_shader_atomic_counter_ops and GL_ARB_shader_group_vote add shader intrinsics supported by all desktop vendors to improve functionality and performance GL_KHR_no_error reduces driver overhead by allowing the application to indicate that it expects error-free operation so errors need not be generated In addition to the above features being added to OpenGL 4.6, the following are being released as extensions:
      GL_KHR_parallel_shader_compile allows applications to launch multiple shader compile threads to improve shader compile throughput WGL_ARB_create_context_no_error and GXL_ARB_create_context_no_error allow no error contexts to be created with WGL or GLX that support the GL_KHR_no_error extension “I’m proud to announce OpenGL 4.6 as the most feature-rich version of OpenGL yet. We've brought together the most popular, widely-supported extensions into a new core specification to give OpenGL developers and end users an improved baseline feature set. This includes resolving previous intellectual property roadblocks to bringing anisotropic texture filtering and polygon offset clamping into the core specification to enable widespread implementation and usage,” said Piers Daniell, chair of the OpenGL Working Group at Khronos. “The OpenGL working group will continue to respond to market needs and work with GPU vendors to ensure OpenGL remains a viable and evolving graphics API for all its customers and users across many vital industries.“
      The OpenGL 4.6 specification can be found at https://khronos.org/registry/OpenGL/index_gl.php. The GLSL to SPIR-V compiler glslang has been updated with GLSL 4.60 support, and can be found at https://github.com/KhronosGroup/glslang.
      Sophisticated graphics applications will also benefit from a set of newly released extensions for both OpenGL and OpenGL ES to enable interoperability with Vulkan and Direct3D. These extensions are named:
      GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_memory_object_win32 GL_EXT_semaphore GL_EXT_semaphore_fd GL_EXT_semaphore_win32 GL_EXT_win32_keyed_mutex They can be found at: https://khronos.org/registry/OpenGL/index_gl.php
      Industry Support for OpenGL 4.6
      “With OpenGL 4.6 our customers have an improved set of core features available on our full range of OpenGL 4.x capable GPUs. These features provide improved rendering quality, performance and functionality. As the graphics industry’s most popular API, we fully support OpenGL and will continue to work closely with the Khronos Group on the development of new OpenGL specifications and extensions for our customers. NVIDIA has released beta OpenGL 4.6 drivers today at https://developer.nvidia.com/opengl-driver so developers can use these new features right away,” said Bob Pette, vice president, Professional Graphics at NVIDIA.
      "OpenGL 4.6 will be the first OpenGL release where conformant open source implementations based on the Mesa project will be deliverable in a reasonable timeframe after release. The open sourcing of the OpenGL conformance test suite and ongoing work between Khronos and X.org will also allow for non-vendor led open source implementations to achieve conformance in the near future," said David Airlie, senior principal engineer at Red Hat, and developer on Mesa/X.org projects.

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    • By _OskaR
      Hi,
      I have an OpenGL application but without possibility to wite own shaders.
      I need to perform small VS modification - is possible to do it in an alternative way? Do we have apps or driver modifictions which will catch the shader sent to GPU and override it?
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