Sign in to follow this  

OpenGL Some questions about bump mapping

Recommended Posts

ehsan2004    178
It seems that bump mapping techniques just deal with diffuse color and one light. 1)So if we want to use bump mapping in our game, it means that we need to disable OpenGL lighting? 2)Which technique creates better result: Parallax or normal map? 3) Do we need to still use old manners such as dot3 extension or cube map ) to implement normal map using OpenGL fixed function? If hardware supports shader, Why not implementing this feature using shader? 4) could we mimic the behavior of more than one light while using bump map? 5) Why the codes on the internet just use the diffuse part of the lighting equation? Is it really difficult to add specular while using bump map for example? 6) Any good article or sample that solves all the problems ?

Share this post

Link to post
Share on other sites
othello    100
Hi. I'll try and answer this the best I can. Please let me know if I've said something incorrect.

1. Yes. You want to do lighting in your shader programs; OpenGL lighting is per-vertex, which causes ugly artifacts.
2. Parallax and normal maps describe different effects. I would recommend using both, because you use the parallax map to displace the normal (and diffuse, specular, etc) map texture coordinates. Also, as a side note, unless you are willing to spend a lot of computing power on parallax mapping, you will probably have artifacts in your image if you implement it.
3. You should definitely use shaders.
4. In general there are two methods for rendering multiple lights. You can either draw multiple passes, one for each light, and alpha blend them together, or you can use deferred shading techniques:
5. It's really easy to add specular. Just use the normal generated by the normal map.
6. Here are some good articles:

Share this post

Link to post
Share on other sites
V-man    813
1) There is no such thing as OpenGL lighting in GL 3.0. GL lighting is part of the fixed pipeline and it has been eliminated. You do your own lighting with shaders now.
2) Parallax is nicer. It is a small change that cost 2 extra GPU cycles in the fragment shader.
3) Not sure what you mean. Cubemaps aren't dead.
The dot3 is part of texture combiners and tex comb is old.
4) You can do multiple lights with a single shader or use multi-pass technique.
5) I'm sure you will be an expert soon and write better and more complete shaders.
6) nope

Share this post

Link to post
Share on other sites
JackTheRapper    150
Diffuse lighting is fairly straight forward to do once the bump map is in place. Highlights are view-dependent so require a bit of extra legwork (e.g. the inverse modelview for the halfway vector to perform in tangent space).

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. 
    • 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