Sign in to follow this  

OpenGL Terrain static lighting

Recommended Posts

esr_ever    130
Hello, I would like an opinion about 2 methods of (static) lighting a mesh of a terrain ( 513 x 513) , in terms of OpenGL texture usage & efficiency. One would be using a 256x256 lightmap, and 4 textures for layers which would repeat over the terrain, and an RGBA texture with the contributions of each layer. After that, the calculation could easily be done using these 6 (!) texture units. The other would be to create just a big (e.g. 4K x 4K) RGB map, with the textures & lightmap baked on it, so I would need only one texture unit & it would be the simplest shader possible. Since the terrain will be viewed from above, I have no need for zooming in/out much, I will only see it from a fixed perspective. So the questions : 1. Which is better, using the huge texture or 6 small ones? ( 1 fetch from a BIG tex vs 6 fetches from smaller ones and a few ops) 2. In case I use the huge one, will it help to have it bound always to a specific texture unit which will only be used for the terrain, in order to avoid successive binds to it? 3. Would it be better to NOT generate mipmaps for the huge one, since the perspective is fixed? or how could I compute the best mipmap level? Thanks in advance, Babis

Share this post

Link to post
Share on other sites
MARS_999    1627
What Gfx are you going to be targeting? 4096x4096 textures aren't supported on older ATI cards IIRC.

I can't say if it would take longer to move one larger texture that was baked with the lighting, or many glBindTexture calls.

If you want to roll with KISS than use the one larger texture and only bind it once. I would still generate mipmaps for the larger texture and use compression.

Share this post

Link to post
Share on other sites
esr_ever    130
Thanks for your answer,

Compression is a must I know, I would use it for all the textures (except the lightmap perhaps). I'm targetting relatively newer hardware, although if needed I could just reduce it to 2K by 2K,that's not a problem. The other method isn't a problem for KISS, I've tried it already in an older app and works fine.
So you suggest I suppose the large texture bound in a unique tex unit, used only for terrain rendering.

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  

  • Partner Spotlight

  • Similar Content

    • By pseudomarvin
      I assumed that if a shader is computationally expensive then the execution is just slower. But running the following GLSL FS instead just crashes
      void main() { float x = 0; float y = 0; int sum = 0; for (float x = 0; x < 10; x += 0.00005) { for (float y = 0; y < 10; y += 0.00005) { sum++; } } fragColor = vec4(1, 1, 1 , 1.0); } with unhandled exception in nvoglv32.dll. Are there any hard limits on the number of steps/time that a shader can take before it is shut down? I was thinking about implementing some time intensive computation in shaders where it would take on the order of seconds to compute a frame, is that possible? Thanks.
    • By Arulbabu Donbosco
      There are studios selling applications which is just copying any 3Dgraphic content and regenerating into another new window. especially for CAVE Virtual reality experience. so that the user opens REvite or CAD or any other 3D applications and opens a model. then when the user selects the rendered window the VR application copies the 3D model information from the OpenGL window. 
      I got the clue that the VR application replaces the windows opengl32.dll file. how this is possible ... how can we copy the 3d content from the current OpenGL window.
      anyone, please help me .. how to go further... to create an application like VR CAVE. 
    • By cebugdev
      hi all,

      i am trying to build an OpenGL 2D GUI system, (yeah yeah, i know i should not be re inventing the wheel, but this is for educational and some other purpose only),
      i have built GUI system before using 2D systems such as that of HTML/JS canvas, but in 2D system, i can directly match a mouse coordinates to the actual graphic coordinates with additional computation for screen size/ratio/scale ofcourse.
      now i want to port it to OpenGL, i know that to render a 2D object in OpenGL we specify coordiantes in Clip space or use the orthographic projection, now heres what i need help about.
      1. what is the right way of rendering the GUI? is it thru drawing in clip space or switching to ortho projection?
      2. from screen coordinates (top left is 0,0 nd bottom right is width height), how can i map the mouse coordinates to OpenGL 2D so that mouse events such as button click works? In consideration ofcourse to the current screen/size dimension.
      3. when let say if the screen size/dimension is different, how to handle this? in my previous javascript 2D engine using canvas, i just have my working coordinates and then just perform the bitblk or copying my working canvas to screen canvas and scale the mouse coordinates from there, in OpenGL how to work on a multiple screen sizes (more like an OpenGL ES question).
      lastly, if you guys know any books, resources, links or tutorials that handle or discuss this, i found one with marekknows opengl game engine website but its not free,
      Just let me know. Did not have any luck finding resource in google for writing our own OpenGL GUI framework.
      IF there are no any available online, just let me know, what things do i need to look into for OpenGL and i will study them one by one to make it work.
      thank you, and looking forward to positive replies.
    • By fllwr0491
      I have a few beginner questions about tesselation that I really have no clue.
      The opengl wiki doesn't seem to talk anything about the details.
      What is the relationship between TCS layout out and TES layout in?
      How does the tesselator know how control points are organized?
          e.g. If TES input requests triangles, but TCS can output N vertices.
             What happens in this case?
      In this article,
      the isoline example TCS out=4, but TES in=isoline.
      And gl_TessCoord is only a single one.
      So which ones are the control points?
      How are tesselator building primitives?
    • By Orella
      I've been developing a 2D Engine using SFML + ImGui.
      Here you can see an image
      The editor is rendered using ImGui and the scene window is a sf::RenderTexture where I draw the GameObjects and then is converted to ImGui::Image to render it in the editor.
      Now I need to create a 3D Engine during this year in my Bachelor Degree but using SDL2 + ImGui and I want to recreate what I did with the 2D Engine. 
      I've managed to render the editor like I did in the 2D Engine using this example that comes with ImGui. 
      3D Editor preview
      But I don't know how to create an equivalent of sf::RenderTexture in SDL2, so I can draw the 3D scene there and convert it to ImGui::Image to show it in the editor.
      If you can provide code will be better. And if you want me to provide any specific code tell me.
  • Popular Now