This topic is now archived and is closed to further replies.


OpenGL Anti-alias - 2D games and Opengl

Recommended Posts

One of the reason why I still like to develop 2d games is the possibility to use detailed models which unfortunatly count a lot of polygons . Till now I have been using direct draw. One problem is that I must disable the anti-alias option before rendering otherwise I get an " aura " around the perimeter when blitting the sprite on the background . Suppose I texture a quad with a anti-aliased sprite and I use opengl as a normal 3d game, making sure the transparent part of the texture is not drawn. Will I face the same problem? Thanks in advance

Share this post

Link to post
Share on other sites
Almost all 3d games use detailed 2d textures on their models but perhaps will it be different some day...

I do not know what anti-alias option you are writing about but the answer is most likely that it will not affect the texture. If you are showing the texture at the same size and it look right do you probably want to disable texture filtering.

Share this post

Link to post
Share on other sites
Yes you can write a 2d basedengine using OGL as long as you set it to Orthographics perspective and you texture your sprites on quads. You will also get rid of that nasty ora you are talking about. The one that get produces bu the outer edges belding to the background color.

In OGL the background color of your sprites will have to be black. All font system use similar texturing on quand to look nice and smooth Look around see what you get out of it...

Share this post

Link to post
Share on other sites
Original post by ANSI2000
In OGL the background color of your sprites will have to be black. All font system use similar texturing on quand to look nice and smooth Look around see what you get out of it...

That''s not true. When you''re using additive blending yes, but for sprites I''d use TGA files with an alpha channel and GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA blending.

Share this post

Link to post
Share on other sites
Hi there,

To color mask your better of with


This is a lot faster than using glBlendFunc and
can be used when rendering both opaque and blended
primitives as GL_BLEND doesnt need to be enabled.

Hope it helps


Share this post

Link to post
Share on other sites
Thanks all of you, for your answer but I am not sure I made myself understood .
Sorry, but English is not my mother language.
In other words.
If I render an anti-aliased human figure, using Poser 4 the quality of the bitmap is excellent.
If I blit the bitmap, using direct draw , the quality of the sprite is poor.
I own two direct x game programming books.
They suggest to disable the anti-alias option when rendering the bitmap.
The quality of the sprite improves but of course it is still worse than the original one.
My question is:
If I use Opengl(textured quads) can I expect to create sprites ) at the same level of quality as the original Poser 4 bitmaps?

Share this post

Link to post
Share on other sites
hi there,

if you dont enable filtering and have a 1:1 ratio with
your quad and texture then you will get ok results,
with no bluring around the edges.

just a tip - if your only using 2d set up the viewing
matrix with gluOrtho2D and use glVertex2i(x,y) or
glVertex2iv(@Pos) for rendering..

Hope it helps


Share this post

Link to post
Share on other sites

  • Announcements

  • Forum Statistics

    • Total Topics
    • Total Posts
  • Similar Content

    • By test opty
      Hi all,
      I'm starting OpenGL using a tut on the Web. But at this point I would like to know the primitives needed for creating a window using OpenGL. So on Windows and using MS VS 2017, what is the simplest code required to render a window with the title of "First Rectangle", please?
    • By DejayHextrix
      Hi, New here. 
      I need some help. My fiance and I like to play this mobile game online that goes by real time. Her and I are always working but when we have free time we like to play this game. We don't always got time throughout the day to Queue Buildings, troops, Upgrades....etc.... 
      I was told to look into DLL Injection and OpenGL/DirectX Hooking. Is this true? Is this what I need to learn? 
      How do I read the Android files, or modify the files, or get the in-game tags/variables for the game I want? 
      Any assistance on this would be most appreciated. I been everywhere and seems no one knows or is to lazy to help me out. It would be nice to have assistance for once. I don't know what I need to learn. 
      So links of topics I need to learn within the comment section would be SOOOOO.....Helpful. Anything to just get me started. 
      Dejay Hextrix 
    • By mellinoe
      Hi all,
      First time poster here, although I've been reading posts here for quite a while. This place has been invaluable for learning graphics programming -- thanks for a great resource!
      Right now, I'm working on a graphics abstraction layer for .NET which supports D3D11, Vulkan, and OpenGL at the moment. I have implemented most of my planned features already, and things are working well. Some remaining features that I am planning are Compute Shaders, and some flavor of read-write shader resources. At the moment, my shaders can just get simple read-only access to a uniform (or constant) buffer, a texture, or a sampler. Unfortunately, I'm having a tough time grasping the distinctions between all of the different kinds of read-write resources that are available. In D3D alone, there seem to be 5 or 6 different kinds of resources with similar but different characteristics. On top of that, I get the impression that some of them are more or less "obsoleted" by the newer kinds, and don't have much of a place in modern code. There seem to be a few pivots:
      The data source/destination (buffer or texture) Read-write or read-only Structured or unstructured (?) Ordered vs unordered (?) These are just my observations based on a lot of MSDN and OpenGL doc reading. For my library, I'm not interested in exposing every possibility to the user -- just trying to find a good "middle-ground" that can be represented cleanly across API's which is good enough for common scenarios.
      Can anyone give a sort of "overview" of the different options, and perhaps compare/contrast the concepts between Direct3D, OpenGL, and Vulkan? I'd also be very interested in hearing how other folks have abstracted these concepts in their libraries.
    • By aejt
      I recently started getting into graphics programming (2nd try, first try was many years ago) and I'm working on a 3d rendering engine which I hope to be able to make a 3D game with sooner or later. I have plenty of C++ experience, but not a lot when it comes to graphics, and while it's definitely going much better this time, I'm having trouble figuring out how assets are usually handled by engines.
      I'm not having trouble with handling the GPU resources, but more so with how the resources should be defined and used in the system (materials, models, etc).
      This is my plan now, I've implemented most of it except for the XML parts and factories and those are the ones I'm not sure of at all:
      I have these classes:
      For GPU resources:
      Geometry: holds and manages everything needed to render a geometry: VAO, VBO, EBO. Texture: holds and manages a texture which is loaded into the GPU. Shader: holds and manages a shader which is loaded into the GPU. For assets relying on GPU resources:
      Material: holds a shader resource, multiple texture resources, as well as uniform settings. Mesh: holds a geometry and a material. Model: holds multiple meshes, possibly in a tree structure to more easily support skinning later on? For handling GPU resources:
      ResourceCache<T>: T can be any resource loaded into the GPU. It owns these resources and only hands out handles to them on request (currently string identifiers are used when requesting handles, but all resources are stored in a vector and each handle only contains resource's index in that vector) Resource<T>: The handles given out from ResourceCache. The handles are reference counted and to get the underlying resource you simply deference like with pointers (*handle).  
      And my plan is to define everything into these XML documents to abstract away files:
      Resources.xml for ref-counted GPU resources (geometry, shaders, textures) Resources are assigned names/ids and resource files, and possibly some attributes (what vertex attributes does this geometry have? what vertex attributes does this shader expect? what uniforms does this shader use? and so on) Are reference counted using ResourceCache<T> Assets.xml for assets using the GPU resources (materials, meshes, models) Assets are not reference counted, but they hold handles to ref-counted resources. References the resources defined in Resources.xml by names/ids. The XMLs are loaded into some structure in memory which is then used for loading the resources/assets using factory classes:
      Factory classes for resources:
      For example, a texture factory could contain the texture definitions from the XML containing data about textures in the game, as well as a cache containing all loaded textures. This means it has mappings from each name/id to a file and when asked to load a texture with a name/id, it can look up its path and use a "BinaryLoader" to either load the file and create the resource directly, or asynchronously load the file's data into a queue which then can be read from later to create the resources synchronously in the GL context. These factories only return handles.
      Factory classes for assets:
      Much like for resources, these classes contain the definitions for the assets they can load. For example, with the definition the MaterialFactory will know which shader, textures and possibly uniform a certain material has, and with the help of TextureFactory and ShaderFactory, it can retrieve handles to the resources it needs (Shader + Textures), setup itself from XML data (uniform values), and return a created instance of requested material. These factories return actual instances, not handles (but the instances contain handles).
      Is this a good or commonly used approach? Is this going to bite me in the ass later on? Are there other more preferable approaches? Is this outside of the scope of a 3d renderer and should be on the engine side? I'd love to receive and kind of advice or suggestions!
    • By nedondev
      I 'm learning how to create game by using opengl with c/c++ coding, so here is my fist game. In video description also have game contain in Dropbox. May be I will make it better in future.
  • Popular Now