Sign in to follow this  
purpledog

OpenGL rendering into a GL_LUMINANCE fbo

Recommended Posts

purpledog    163
Hi, Does anybody know how if it is possible to create a 16 bits (or 8bits) fbo? Using GL_LUMINANCE16 doesn't work. float and integer format works but it doesn't fit my needs. The opengl registry says:
Quote:
Although an early draft of the FBO specification permitted rendering into alpha, luminance, and intensity formats, this this capability was pulled when it was realized that it was under-specified exactly how rendering into these formats would work. (specifically, how R/G/B/A map to I/L/A) To resolve this we seem to have two options: A. Add new R and RG formats like NV_float_buffer did. B. For the existing one- and two- component formats, define the mapping from RGBA components to ILA components. The superbuffers group has informally decided that option A is preferable.
But I cannot find any "GL_RED16" anywhere :-( Any idea??

Share this post


Link to post
Share on other sites
Yann L    1802
Well, the paragraph just above the one you quoted says it all:
Quote:

Presently none of the one- or two- component texture formats
defined in unextended OpenGL is color-renderable. The R
and RG float formats defined by the NV_float_buffer
extension are color-renderable.

So use GL_FLOAT_R_NV or GL_FLOAT_RG_NV.

[rant]
Of course, all this is incredibly retarded. It introduces again a dependency on NV specific stuff. The ARB really needs to get their heads pulled out of their asses one of these days. "We can't define the RGB to ILA mappings, OMG OMG" is not an excuse to completely remove a vital feature such as rendering to a one or two component format. It's just pure stupidity. As usual, NV tries to save the day by adding the feature as a vendor dependent extension, but this doesn't really help a lot. IMO, all ARB members should be fired, and the control of the OpenGL standard handed over to Nvidia...
[/rant]

Share this post


Link to post
Share on other sites
purpledog    163
I don't understand, both you and the gl spec actually... :-(
As I said, I don't want to use float texture...
So I guess the answer to my question is "no, you cannot do it".

Or maybe there's a strange mixture of type/format/internalformat that could do the trick?

Share this post


Link to post
Share on other sites
purpledog    163
Ok, so the conclusion so far is that it is not possible to render into a GL_LUMINANCE8 or GL_LUMINANCE16, which almost looks surrealistic in 2008...

Oh well... Fair enough... Who needs to save bandwith anyway ;-)

Share this post


Link to post
Share on other sites
Yann L    1802
Quote:
Original post by purpledog
Ok, so the conclusion so far is that it is not possible to render into a GL_LUMINANCE8 or GL_LUMINANCE16,

Yep, unfortunately that's correct. The only officially supported single or two component formats are GL_FLOAT_R_NV and GL_FLOAT_RG_NV (and derivatives). GL_LUMINANCE might work (and it does on certain NV cards / driver revisions), but that's completely unsupported from the official side (ie. ARB specs). Single/dual component integer texture formats might work (I never tried it, and the specs are unclear about this point).

So either you go floating point, or you waste space with an RGB(A) surface.

Quote:
Original post by purpledog
which almost looks surrealistic in 2008...

See my rant above. The ARB is a joke.

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  

  • 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. 
       
      Thanks
    • 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,
      http://www.informit.com/articles/article.aspx?p=2120983
      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.
      Thanks!
  • Popular Now