Sign in to follow this  
Miguel71

OpenGL Lighting - Lightmaps and bumpmaps

Recommended Posts

Hi, I am currently working on a game engine and I have a problem.

 

I want to introduce lighting to my engine. I know the opengl has only 8 lights so I need to implement my own lighting system. I've tried somee simple fragment shaders to do that but the performance is poor when i use many lights. So I think that I need to use lightmaps on the static geometry.

 

My question is how can I implement bumpmapping using lightmaps(or any other way to do lighting)?

Share this post


Link to post
Share on other sites

Just to point out when you say "8 lights" it means that for each rendering call you can have up to 8 lights defined. You should be able to find out which lights affect which objects (typically only few) and set the lights for each draw call. 

 

Of course, all that fixed function stuff is implemented with shaders nowadays, and making your own lighting system isn't a bad idea. 

 

Cheers!

Share this post


Link to post
Share on other sites

Lightmaps are very suitable for static geometry lighting... and advanced directional lightmapping can even be used for semi-dynamic model lighting (light changes on model depending or their position in the map)

 

Basically you first have to know how to bake a lightmap.. I use the method described here: http://forum.unity3d.com/threads/8998-Making-lightmaps-in-Maya-(tutorial)

 

Then implementing it on the code side.. you basically have to have a "duplicate" model of your map, with identical geometry.. You use that to create the lightmap so it gets new uv's... You import the UV's from the lightmap, pass them to the fragment shader, use them to do a texture lookup with the lightmap texture using the same UV coords, and lightply in the result

Share this post


Link to post
Share on other sites

kauna has the best reply.

Doing baked lighting or writing a deferred renderer is an extremely long way to go out of one’s way just because of a simple misunderstanding about how many lights are supported in OpenGL.

 

To be clear: The limit on the number of lights in OpenGL’s fixed-function pipeline is limited only by the amount of memory on your machine.

The limit is 8 at a time.

There is nothing stopping you from rendering using 8 lights, then again with 8 more, and again, etc., until all 20,000 lights in your scene have been processed (never try this at home kids).

Lighting is additive, so each pass simply adds on top of the previous.

 

 

Also mentioned was that you really should be using shaders anyway.  Deferred renderers requires shaders in the first place, and it is still much easier to switch to shaders than to bake and use lightmaps.

 

 

L. Spiro

Share this post


Link to post
Share on other sites

Thanks for the replies! Although I am going to use the old opengl(probably 2.1) I dont want to use the fixed-function functionality, and I have sucessfully implemented lighting by shaders. The thing is that I want to do per fragment lighting, wich I found to be slow when using multiple lights.

 

I've done some research about deferred rendering and it seams to be my best option. I've sucessfuly made the G-Buffer but i'm having trouble doing the light pass. I'm not sure if I should create another topic about that or not, but i will post part of my code and stuff.

 

normals

BFJCBl0.png

 

position

pVKulul.png

 

diffuse

 

Bslwqml.png

 

I think those are okay. Here is my shader that generates those:

varying vec4 color;
varying vec2 texCoords;

varying vec3 N;

varying vec3 pos;

void main() {
    color = gl_Color.rgba;
    gl_Position = ftransform();
    texCoords = gl_MultiTexCoord0.xy;

    N = normalize(gl_NormalMatrix * gl_Normal);
	
	pos = vec4(ftransform()).xyz;
}

varying vec4 color;
varying vec2 texCoords;
uniform sampler2D textureSampler;

varying vec3 N;
varying vec3 v;

varying vec3 pos;

void main()
{
	gl_FragData[0] = color * texture2D(textureSampler, texCoords);
	gl_FragData[1] = vec4(N, 1.0);
	gl_FragData[2] = vec4(pos, 1.0);
	gl_FragData[3] = vec4(texCoords, 0.0, 1.0);
}

and here is my lighting shader

varying vec2 texCoords;

void main() {
    gl_Position = ftransform();
    texCoords = gl_MultiTexCoord0.xy;
}
varying vec2 texCoords;
uniform sampler2D DSampler;//Diffuse
uniform sampler2D NSampler;//Normals
uniform sampler2D PSampler;//Positions
void main(){
	vec3 lpos = vec3(0, 0, 52);
	
	vec3 v = texture2D(PSampler, texCoords).rgb;
	vec3 N = texture2D(NSampler, texCoords).rgb;
	
	vec3 L = normalize(lpos - v);   
	vec4 Idiff = gl_FrontLightProduct[0].diffuse * max(dot(N,L), 0.0);  
	Idiff = clamp(Idiff, 0.0, 1.0);
	
	gl_FragColor = Idiff * texture2D(DSampler, texCoords);
}

What is wrong with those. Everything is black.

 

Thanks.

Share this post


Link to post
Share on other sites
First you do max(dot(N,L), 0.0);, which always produces a negative number or 0, and then you do clamp(Idiff, 0.0, 1.0);, which clamps between 0 and 1.

The only value that can get through that unharmed is 0, and all other values will become 0.


L. Spiro

Share this post


Link to post
Share on other sites

Well, to be honest I don't know how to fix that, i tried putting a minus before max(dot(N,L), 0.0), but that didnt work, so I removed clamp, but that didn't affect anything idk why.

Also, it actualy is working, I probably set the light in a bad position or something. My problem now is that it is upside down and the light is a bit strange. Here are some pictures of it in comparison with forward rendering:

 

Forward rendering

KJg5Im1.png

 

Deferred rendering

 

DVLdeIq.png

 

Idk what is wrong with it. Can somebody help me?

Thanks again. smile.png

 

PS:

Also, could someone tell me if you deferred rendering or forward rendering in your game/engine?

Edited by Miguel71

Share this post


Link to post
Share on other sites

I use forward rendering with some nice tricks for simple&fast dynamic lighting. I find filling the gbuffer of deferred is just too large an overhead... So it's really only worth it if you have "A LOT" of *active* (on screen and visible) dynamic lights.

 

http://www.youtube.com/watch?v=XM5jVwk_oP8

 

This is all done on a crappy card at ~200 FPS

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  

  • Forum Statistics

    • Total Topics
      628277
    • Total Posts
      2981776
  • Similar Content

    • 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!
      Thanks!
    • 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.
      Thanks.
    • By Abecederia
      So I've recently started learning some GLSL and now I'm toying with a POM shader. I'm trying to optimize it and notice that it starts having issues at high texture sizes, especially with self-shadowing.
      Now I know POM is expensive either way, but would pulling the heightmap out of the normalmap alpha channel and in it's own 8bit texture make doing all those dozens of texture fetches more cheap? Or is everything in the cache aligned to 32bit anyway? I haven't implemented texture compression yet, I think that would help? But regardless, should there be a performance boost from decoupling the heightmap? I could also keep it in a lower resolution than the normalmap if that would improve performance.
      Any help is much appreciated, please keep in mind I'm somewhat of a newbie. Thanks!
    • By test opty
      Hi,
      I'm trying to learn OpenGL through a website and have proceeded until this page of it. The output is a simple triangle. The problem is the complexity.
      I have read that page several times and tried to analyse the code but I haven't understood the code properly and completely yet. This is the code:
       
      #include <glad/glad.h> #include <GLFW/glfw3.h> #include <C:\Users\Abbasi\Desktop\std_lib_facilities_4.h> using namespace std; //****************************************************************************** void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow *window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; const char *vertexShaderSource = "#version 330 core\n" "layout (location = 0) in vec3 aPos;\n" "void main()\n" "{\n" " gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n" "}\0"; const char *fragmentShaderSource = "#version 330 core\n" "out vec4 FragColor;\n" "void main()\n" "{\n" " FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n" "}\n\0"; //******************************* int main() { // glfw: initialize and configure // ------------------------------ glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // glfw window creation GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "My First Triangle", nullptr, nullptr); if (window == nullptr) { cout << "Failed to create GLFW window" << endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { cout << "Failed to initialize GLAD" << endl; return -1; } // build and compile our shader program // vertex shader int vertexShader = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vertexShader, 1, &vertexShaderSource, nullptr); glCompileShader(vertexShader); // check for shader compile errors int success; char infoLog[512]; glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success); if (!success) { glGetShaderInfoLog(vertexShader, 512, nullptr, infoLog); cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << endl; } // fragment shader int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fragmentShader, 1, &fragmentShaderSource, nullptr); glCompileShader(fragmentShader); // check for shader compile errors glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success); if (!success) { glGetShaderInfoLog(fragmentShader, 512, nullptr, infoLog); cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << endl; } // link shaders int shaderProgram = glCreateProgram(); glAttachShader(shaderProgram, vertexShader); glAttachShader(shaderProgram, fragmentShader); glLinkProgram(shaderProgram); // check for linking errors glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success); if (!success) { glGetProgramInfoLog(shaderProgram, 512, nullptr, infoLog); cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << endl; } glDeleteShader(vertexShader); glDeleteShader(fragmentShader); // set up vertex data (and buffer(s)) and configure vertex attributes float vertices[] = { -0.5f, -0.5f, 0.0f, // left 0.5f, -0.5f, 0.0f, // right 0.0f, 0.5f, 0.0f // top }; unsigned int VBO, VAO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); // bind the Vertex Array Object first, then bind and set vertex buffer(s), //and then configure vertex attributes(s). glBindVertexArray(VAO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // note that this is allowed, the call to glVertexAttribPointer registered VBO // as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind glBindBuffer(GL_ARRAY_BUFFER, 0); // You can unbind the VAO afterwards so other VAO calls won't accidentally // modify this VAO, but this rarely happens. Modifying other // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind // VAOs (nor VBOs) when it's not directly necessary. glBindVertexArray(0); // uncomment this call to draw in wireframe polygons. //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); // render loop while (!glfwWindowShouldClose(window)) { // input // ----- processInput(window); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // draw our first triangle glUseProgram(shaderProgram); glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to // bind it every time, but we'll do so to keep things a bit more organized glDrawArrays(GL_TRIANGLES, 0, 3); // glBindVertexArray(0); // no need to unbind it every time // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) glfwSwapBuffers(window); glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources. glfwTerminate(); return 0; } //************************************************** // process all input: query GLFW whether relevant keys are pressed/released // this frame and react accordingly void processInput(GLFWwindow *window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } //******************************************************************** // glfw: whenever the window size changed (by OS or user resize) this callback function executes void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); } As you see, about 200 lines of complicated code only for a simple triangle. 
      I don't know what parts are necessary for that output. And also, what the correct order of instructions for such an output or programs is, generally. That start point is too complex for a beginner of OpenGL like me and I don't know how to make the issue solved. What are your ideas please? What is the way to figure both the code and the whole program out correctly please?
      I wish I'd read a reference that would teach me OpenGL through a step-by-step method. 
  • Popular Now