• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0

OpenGL TTF (theory)

9 posts in this topic

I need to make a TrueType/FreeType font renderer. So, I wanted to sort out my thoughts. I just want an overall theory how to make it.


Below are my thoughts how to make it. Please give feedback if it makes sense or not (or if it can be done easier/better). Even just one line answer would be enough (so I know if I'm going in the right direction).



Backstory and my requirements

I need basicly a typical 2D print(), without extras (I just setup an Ortho projection and use pixel perfect coordinates for everything, in practice not distinguishable from any 2D API, except speed). Right now I'm using SDL_TTF but it's soooo slow it's not bearable at all :) So, I mostly need just a relatively fast 2D TTF renderer that works with OpenGL 2.0 (note I don't need the fastest possible solution, just fast enough, I don't want to spend too much time on making YetAnotherFontRenderer, I just want one that is acceptable and then move on to making a game :) ). I was also considering using a library for this but after checking several I concluded it would be faster to write one (poor documentation, too high hardware requirements - use of shaders, overall bloated code, etc).



1. Data

After big disappointment of SDL_TTF's performance I think I should use strictly my internal font format (texture with glyphs + table with various metrics), a TTF library would be used only to create the initial internal font file (TTF is simply not suitable for real time rendering). The game would first try to load the internal font file, if not present it would create it, save it and then attempt to load again (fast load).


2. Font size

I think I will treat various sizes of the same font (like 12 and 16) as completely separate fonts. Checking how I use fonts in practice so far it's completelly sufficient. I would skip all OpenGL resize (not really needed in my case and a font rendered for exactly the destination size should be always a bit prettier).


3. Colours

I'm not sure how antialiasing works, but wouldn't it be sufficient to render white font to the texture and then use glColor() before rendering the text? Instead of preparing separate textures for each colour?




Share this post

Link to post
Share on other sites

Requirements details:

- simpliest texture based rendering (it's just for simulating a traditional 2D text rendering)

- only 8 bit latin languages (256 chars max), left to right only. In around 99% cases I would not even need this and just use ASCII.

- needs to work under OpenGL 2.0 (would prefer 1.5 but that's not that important and I can live without it)

- decently fast (no need for the fastest possible) without being too troublesome to code (my goal is to make fun games, not efficient engines)


Are you sure this is SDL_TTF's performance, versus the performance of your copying the resulting text into a texture?


Usually the main bottleneck here is copying and uploading the texture to the GPU. Make sure that your SDL text surface is power-of-two sized, that your SDL text surface has the same channel layout as your texture, and that you are updating an existing texture rather than uploading a new one each time (use glTexSubImage2D).

Interesting... But even if, finetuning the copying part of the code would be at least as difficult, if not more, than making a simple texture based renderer. Plus it does not guarantee speed (it would still be slower in the end, since it has to go through SDL_surface before copying to a texture). One note I had SDL_TTF version of a library that way quite fast, but it was rendering it incorrectly. Then I switched to a newer version and it was correct but unacceptably slow. Anyway, it sounds to me as even more work than writing a texture based font renderer from scratch.


Share this post

Link to post
Share on other sites

you can use libfreetype to generate textures of a ttf font at any size.  It's fairly easy to get these into GL


Share this post

Link to post
Share on other sites

Have you considered using glfont? I found it was quite simple to integrate into my application and it works great (and fast).


Share this post

Link to post
Share on other sites

[quote name='zacaj' timestamp='1358372514' post='5022314']
you can use libfreetype to generate textures of a ttf font at any size.  It's fairly easy to get these into GL[/quote]

Or use the much simpler/smaller stb_truetype.h for the same purpose.


Share this post

Link to post
Share on other sites

[quote name='Acharis' timestamp='1358372233' post='5022312']
Plus it does not guarantee speed (it would still be slower in the end, since it has to go through SDL_surface before copying to a texture).[/quote]

That pretty much depends whether you are bottlenecked on the GPU, CPU or bandwidth (and whether you need advanced text rendering capabilities).


Text rendering on the GPU is a bit of a misnomer, since you have to do all the text layout, kerning, etc. on the CPU anyway, and you are basically just using the GPU to push textured quads to the screen (the same as in the SDL_ttf case).


But assuming you do want to go the GPU route, it basically boils down to loading the glyphs for all of ascii into a single texture, and then writing some fancy CPU-side text layout code that outputs a vertex buffer with the texture coordinates adjusted as needed to pick the right portion of the texture for each quad...


Share this post

Link to post
Share on other sites

One solution is also to use libRocket. The disadvantage is that it is a big library and takes some effort to interface. But the advantage is that you can create nice off-line definitions in a html/CSS-lookalike format. It can be used for both OpenGL 3+ and OpenGL 2+. It also has good support for decorations.


Share this post

Link to post
Share on other sites

My approach is to lazy-render each separate glyph into opengl texture and update it if more glyphs are needed. Store information about every glyph and it's position on the texture. Rendering is amazingly fast, it is just mapping the right texture coordinates for each glyph. And it opens very nice possibilities for text effects.


Implementation consists of:

- Glyph object, which has glyph measurements and it's cached position of surface, as well as reference to opengl texture.

- A Factory object used to get glyph or return existing one based on char code. It manages unlimited surfaces for a specificly - sized font.

- A Surface to keep rendered glyphs on. I am always keeping SDL surface in memory, and refreshing opengl surface only on change or if opengl context is lost (resize).


Then I can have various text objects to render these glyphs in various interesting ways.

Color: I pre-render glyphs as white and use blending for color, as you said.


This is a crappy version of this approach written quite a long time ago: http://code.google.com/p/glstext/

Since I have rewrote all of it last week, I may share the code if anyone is interested. I even managed to get the kerning working, which is oh-so-amazing smile.png

Edited by Nercury

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By Toastmastern
      So it's been a while since I took a break from my whole creating a planet in DX11. Last time around I got stuck on fixing a nice LOD.
      A week back or so I got help to find this:
      In general this is what I'm trying to recreate in DX11, he that made that planet LOD uses OpenGL but that is a minor issue and something I can solve. But I have a question regarding the code
      He gets the position using this row
      vec4d pos = b.var.vec4d["position"]; Which is then used further down when he sends the variable "center" into the drawing function:
      if (pos.len() < 1) pos.norm(); world::draw(vec3d(pos.x, pos.y, pos.z));  
      Inside the draw function this happens:
      draw_recursive(p3[0], p3[1], p3[2], center); Basically the 3 vertices of the triangle and the center of details that he sent as a parameter earlier: vec3d(pos.x, pos.y, pos.z)
      Now onto my real question, he does vec3d edge_center[3] = { (p1 + p2) / 2, (p2 + p3) / 2, (p3 + p1) / 2 }; to get the edge center of each edge, nothing weird there.
      But this is used later on with:
      vec3d d = center + edge_center[i]; edge_test[i] = d.len() > ratio_size; edge_test is then used to evaluate if there should be a triangle drawn or if it should be split up into 3 new triangles instead. Why is it working for him? shouldn't it be like center - edge_center or something like that? Why adding them togheter? I asume here that the center is the center of details for the LOD. the position of the camera if stood on the ground of the planet and not up int he air like it is now.

      Full code can be seen here:
      If anyone would like to take a look and try to help me understand this code I would love this person. I'm running out of ideas on how to solve this in my own head, most likely twisted it one time to many up in my head
      Thanks in advance
    • By fllwr0491
      I googled around but are unable to find source code or details of implementation.
      What keywords should I search for this topic?
      Things I would like to know:
      A. How to ensure that partially covered pixels are rasterized?
         Apparently by expanding each triangle by 1 pixel or so, rasterization problem is almost solved.
         But it will result in an unindexable triangle list without tons of overlaps. Will it incur a large performance penalty?
      B. A-buffer like bitmask needs a read-modiry-write operation.
         How to ensure proper synchronizations in GLSL?
         GLSL seems to only allow int32 atomics on image.
      C. Is there some simple ways to estimate coverage on-the-fly?
         In case I am to draw 2D shapes onto an exisitng target:
         1. A multi-pass whatever-buffer seems overkill.
         2. Multisampling could cost a lot memory though all I need is better coverage.
            Besides, I have to blit twice, if draw target is not multisampled.
    • By mapra99

      I am working on a recent project and I have been learning how to code in C# using OpenGL libraries for some graphics. I have achieved some quite interesting things using TAO Framework writing in Console Applications, creating a GLUT Window. But my problem now is that I need to incorporate the Graphics in a Windows Form so I can relate the objects that I render with some .NET Controls.

      To deal with this problem, I have seen in some forums that it's better to use OpenTK instead of TAO Framework, so I can use the glControl that OpenTK libraries offer. However, I haven't found complete articles, tutorials or source codes that help using the glControl or that may insert me into de OpenTK functions. Would somebody please share in this forum some links or files where I can find good documentation about this topic? Or may I use another library different of OpenTK?

    • By Solid_Spy
      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
  • Popular Now