• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
B_old

OpenGL
Proper use of VAO

17 posts in this topic

I have some experience with D3D11 but am currently looking into OpenGL.

 

I noticed that in OpenGL both the vertex buffers and the vertex layout are encapsulated together in a vertex array object.

Suppose I have a properly set up VAO and now decide that I want to use different vertex buffers that contain data in the same layout as before. At first I though I have to create a new VAO for this.

 

But then I stumbled over this quote in a text about vertex specifiation:

 

 

Better yet, if you want to use the same format but move the buffer around, it only takes one function call; namely glBindVertexBuffer? with a buffer binding of 0. [...] Note again that all of the above state is still VAO state. It is all encapsulated in vertex array objects.
regarding the usage of glVertexAttribBinding and glVertexAttribFormat. So I assume there muss be a better way.
 
My new theory on the proper usage of VAO is that I set them up with glVertexAttribFormat according to my vertex layout once and when I want switch buffers I bind the VAO but only change the glVertexAttribBinding.
Is this correct?
0

Share this post


Link to post
Share on other sites

Phrases like "move the buffer around" and "switch buffers" and "proper usage" are vaguer than they seem, considering that vertex array objects are an entirely optional superstructure to organize buffers and other objects: you can put into a VAO the vertex drawing state that used to be global, with a few new VAO-aware functions.

 

The quoted wiki passage means only that you can bind any VBO to the same "binding point" of a VAO, and it will be interpreted according to the VAO's layout, specified once independently of what buffers are bound. You need to call glVertexAttribBinding when you bind different buffers only if they are laid out differently after all.

 

If you want to define a vertex and vertex buffer layout once and use it with different buffer content, you it's very likely that since they have the same layout your data sets can live together in the same VBOs in, letting you use indexes to draw one or the other without binding or memory tricks.

glVertexAttribBinding
0

Share this post


Link to post
Share on other sites

Phrases like "move the buffer around" and "switch buffers" and "proper usage" are vaguer than they seem, considering that vertex array objects are an entirely optional superstructure to organize buffers and other objects: you can put into a VAO the vertex drawing state that used to be global, with a few new VAO-aware functions.

Do you mean by optional, that I don't have to use VAOs at all?

 

If you want to define a vertex and vertex buffer layout once and use it with different buffer content, you it's very likely that since they have the same layout your data sets can live together in the same VBOs in, letting you use indexes to draw one or the other without binding or memory tricks.

I was thinking about a scenario where I calculate the lighting for a model and the shader expects normals, tangents etc.. Later I calculate the the shadow where only positions are expected. If the normals and tangents reside in a separate buffer there is no need to bind it in that case.

 

I was thinking along the lines of D3D's InputLayout.

Edited by B_old
0

Share this post


Link to post
Share on other sites

 

If you want to define a vertex and vertex buffer layout once and use it with different buffer content, you it's very likely that since they have the same layout your data sets can live together in the same VBOs in, letting you use indexes to draw one or the other without binding or memory tricks.

I was thinking about a scenario where I calculate the lighting for a model and the shader expects normals, tangents etc.. Later I calculate the the shadow where only positions are expected. If the normals and tangents reside in a separate buffer there is no need to bind it in that case.

You might set up two vertex array objects, one for the lighting pass state and one for the shadow pass state, and two vertex buffer objects, one containing positions and one containing "normals, tangents, etc."; then you could bind the positions buffer in both vertex array objects and the other buffer in the lighting pass VAO only.

When you bind the appropriate VAO, OpenGL automatically recalls what vertex buffers are in use, and their layout.

0

Share this post


Link to post
Share on other sites

You might set up two vertex array objects, one for the lighting pass state and one for the shadow pass state, and two vertex buffer objects, one containing positions and one containing "normals, tangents, etc."; then you could bind the positions buffer in both vertex array objects and the other buffer in the lighting pass VAO only.

When you bind the appropriate VAO, OpenGL automatically recalls what vertex buffers are in use, and their layout.

That sounds complicated.

I was hoping there is a method more akin to D3D. It is easier to keep track off many vertex buffers and a few input layouts than many vertex buffers and two times (or more) that many vertex array objects.

0

Share this post


Link to post
Share on other sites

 


vertex array objects are an entirely optional superstructure to organize buffers

 

This is not true for core OpenGL. See for example http://www.opengl.org/wiki/GLAPI/glVertexAttribPointer which states "GL_INVALID_OPERATION? is generated if no vertex array object is bound."

 

 

At the same time, it remains semi-optional; a common tactic is to create and bind a single VAO after context creation, following which you can continue to code as before and pretend VAOs never existed.

1

Share this post


Link to post
Share on other sites

 

 


vertex array objects are an entirely optional superstructure to organize buffers

 

This is not true for core OpenGL. See for example http://www.opengl.org/wiki/GLAPI/glVertexAttribPointer which states "GL_INVALID_OPERATION? is generated if no vertex array object is bound."

 

 

At the same time, it remains semi-optional; a common tactic is to create and bind a single VAO after context creation, following which you can continue to code as before and pretend VAOs never existed.

 

I wouldn't really recommend it, but it is possible, yes. Even so you do need at least one VAO, so "entirely optional" isn't entirely true.

0

Share this post


Link to post
Share on other sites

I wouldn't really recommend it, but it is possible, yes. Even so you do need at least one VAO, so "entirely optional" isn't entirely true.

Would you say, that the proper OpenGL style is to have two VAO per model for instance? One for the lighting/g-buffer passe(s) and another for shadow passes.

 

In that case I don't understand the benefit of the 4.3 glBindVertexBuffer(), because it now seems it should still happen in a initialization phase.

0

Share this post


Link to post
Share on other sites

 

 

 


vertex array objects are an entirely optional superstructure to organize buffers

 

This is not true for core OpenGL. See for example http://www.opengl.org/wiki/GLAPI/glVertexAttribPointer which states "GL_INVALID_OPERATION? is generated if no vertex array object is bound."

 

 

At the same time, it remains semi-optional; a common tactic is to create and bind a single VAO after context creation, following which you can continue to code as before and pretend VAOs never existed.

 

I wouldn't really recommend it, but it is possible, yes. Even so you do need at least one VAO, so "entirely optional" isn't entirely true.

 

 

Well id do it, Valve do it, so it seems (at least on the surface) to be viable.  Despite that, I do find VAOs useful as a way to avoid having to track lots of state, but I'm still looking forward to GL_ARB_vertex_attrib_binding being more widely available.

1

Share this post


Link to post
Share on other sites

 

I wouldn't really recommend it, but it is possible, yes. Even so you do need at least one VAO, so "entirely optional" isn't entirely true.

Would you say, that the proper OpenGL style is to have two VAO per model for instance? One for the lighting/g-buffer passe(s) and another for shadow passes.

 

In that case I don't understand the benefit of the 4.3 glBindVertexBuffer(), because it now seems it should still happen in a initialization phase.

 

Why would you need two different VAOs for that? Just don't use the normal information in the shadow pass shaders. If you maintain consistent attribute locations between shaders, a single VAO per mesh should do, IMO.

0

Share this post


Link to post
Share on other sites

 

I wouldn't really recommend it, but it is possible, yes. Even so you do need at least one VAO, so "entirely optional" isn't entirely true.

 

 

Well id do it, Valve do it, so it seems (at least on the surface) to be viable.  Despite that, I do find VAOs useful as a way to avoid having to track lots of state, but I'm still looking forward to GL_ARB_vertex_attrib_binding being more widely available.

 

It is obviously doable/viable but why track all that state yourself, when the API can do it for you (which may have the side effect of being more efficient)?

Edited by l0calh05t
0

Share this post


Link to post
Share on other sites

Why would you need two different VAOs for that? Just don't use the normal information in the shadow pass shaders. If you maintain consistent attribute locations between shaders, a single VAO per mesh should do, IMO.

But wouldn't you waste bandwidth that way?

0

Share this post


Link to post
Share on other sites

Well id do it, Valve do it, so it seems (at least on the surface) to be viable.  Despite that, I do find VAOs useful as a way to avoid having to track lots of state, but I'm still looking forward to GL_ARB_vertex_attrib_binding being more widely available.

Did you get this info from this presentation about porting the source engine to OpenGL? Because I did not quite understand the part about VAOs.

0

Share this post


Link to post
Share on other sites

 

Why would you need two different VAOs for that? Just don't use the normal information in the shadow pass shaders. If you maintain consistent attribute locations between shaders, a single VAO per mesh should do, IMO.

But wouldn't you waste bandwidth that way?

 

Unlikely. As the driver knows which attributes are actually used by the shader and the shader has no reason to access that memory. Performance will not be optimal if your attributes are interleaved, but unbinding the interleaved attributes won't change that. In any case, if you need performance: profile.

0

Share this post


Link to post
Share on other sites

Unlikely. As the driver knows which attributes are actually used by the shader and the shader has no reason to access that memory. Performance will not be optimal if your attributes are interleaved, but unbinding the interleaved attributes won't change that. In any case, if you need performance: profile.

Even if the data is not accessed it still takes up bandwidth if the data is interleaved, right?

But if you only partly interleave the vertex data and partly keep it in separate streams you can potentially skip a stream thus saving bandwidth.

0

Share this post


Link to post
Share on other sites

 

Unlikely. As the driver knows which attributes are actually used by the shader and the shader has no reason to access that memory. Performance will not be optimal if your attributes are interleaved, but unbinding the interleaved attributes won't change that. In any case, if you need performance: profile.

Even if the data is not accessed it still takes up bandwidth if the data is interleaved, right?

But if you only partly interleave the vertex data and partly keep it in separate streams you can potentially skip a stream thus saving bandwidth.

 

 

But at the higher cost of drawing non-interleaved verts.

 

This is one that there is no "correct in every case" answer to.  One really needs to profile and find which option is best for one's own case, not forgetting to watch out for factors that you can't directly measure (i.e. bandwidth cost can be measured but the higher cost of drawing non-interleaved data is not immediately obvious).

1

Share this post


Link to post
Share on other sites

But at the higher cost of drawing non-interleaved verts.

 

This is one that there is no "correct in every case" answer to.  One really needs to profile and find which option is best for one's own case, not forgetting to watch out for factors that you can't directly measure (i.e. bandwidth cost can be measured but the higher cost of drawing non-interleaved data is not immediately obvious).

Fair enough.

Could you please elaborate more on Valve's VAO usage? Are you referring to the presentation I linked?

0

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  
Followers 0

  • Similar Content

    • By Solid_Spy
      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By DaniDesu
      #include "MyEngine.h" int main() { MyEngine myEngine; myEngine.run(); return 0; } MyEngine.h
      #pragma once #include "MyWindow.h" #include "MyShaders.h" #include "MyShapes.h" class MyEngine { private: GLFWwindow * myWindowHandle; MyWindow * myWindow; public: MyEngine(); ~MyEngine(); void run(); }; MyEngine.cpp
      #include "MyEngine.h" MyEngine::MyEngine() { MyWindow myWindow(800, 600, "My Game Engine"); this->myWindow = &myWindow; myWindow.createWindow(); this->myWindowHandle = myWindow.getWindowHandle(); // Load all OpenGL function pointers for use gladLoadGLLoader((GLADloadproc)glfwGetProcAddress); } MyEngine::~MyEngine() { this->myWindow->destroyWindow(); } void MyEngine::run() { MyShaders myShaders("VertexShader.glsl", "FragmentShader.glsl"); MyShapes myShapes; GLuint vertexArrayObjectHandle; float coordinates[] = { 0.5f, 0.5f, 0.0f, 0.5f, -0.5f, 0.0f, -0.5f, 0.5f, 0.0f }; vertexArrayObjectHandle = myShapes.drawTriangle(coordinates); while (!glfwWindowShouldClose(this->myWindowHandle)) { glClearColor(0.5f, 0.5f, 0.5f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Draw something glUseProgram(myShaders.getShaderProgram()); glBindVertexArray(vertexArrayObjectHandle); glDrawArrays(GL_TRIANGLES, 0, 3); glfwSwapBuffers(this->myWindowHandle); glfwPollEvents(); } } MyShaders.h
      #pragma once #include <glad\glad.h> #include <GLFW\glfw3.h> #include "MyFileHandler.h" class MyShaders { private: const char * vertexShaderFileName; const char * fragmentShaderFileName; const char * vertexShaderCode; const char * fragmentShaderCode; GLuint vertexShaderHandle; GLuint fragmentShaderHandle; GLuint shaderProgram; void compileShaders(); public: MyShaders(const char * vertexShaderFileName, const char * fragmentShaderFileName); ~MyShaders(); GLuint getShaderProgram(); const char * getVertexShaderCode(); const char * getFragmentShaderCode(); }; MyShaders.cpp
      #include "MyShaders.h" MyShaders::MyShaders(const char * vertexShaderFileName, const char * fragmentShaderFileName) { this->vertexShaderFileName = vertexShaderFileName; this->fragmentShaderFileName = fragmentShaderFileName; // Load shaders from files MyFileHandler myVertexShaderFileHandler(this->vertexShaderFileName); this->vertexShaderCode = myVertexShaderFileHandler.readFile(); MyFileHandler myFragmentShaderFileHandler(this->fragmentShaderFileName); this->fragmentShaderCode = myFragmentShaderFileHandler.readFile(); // Compile shaders this->compileShaders(); } MyShaders::~MyShaders() { } void MyShaders::compileShaders() { this->vertexShaderHandle = glCreateShader(GL_VERTEX_SHADER); this->fragmentShaderHandle = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(this->vertexShaderHandle, 1, &(this->vertexShaderCode), NULL); glShaderSource(this->fragmentShaderHandle, 1, &(this->fragmentShaderCode), NULL); glCompileShader(this->vertexShaderHandle); glCompileShader(this->fragmentShaderHandle); this->shaderProgram = glCreateProgram(); glAttachShader(this->shaderProgram, this->vertexShaderHandle); glAttachShader(this->shaderProgram, this->fragmentShaderHandle); glLinkProgram(this->shaderProgram); return; } GLuint MyShaders::getShaderProgram() { return this->shaderProgram; } const char * MyShaders::getVertexShaderCode() { return this->vertexShaderCode; } const char * MyShaders::getFragmentShaderCode() { return this->fragmentShaderCode; } MyWindow.h
      #pragma once #include <glad\glad.h> #include <GLFW\glfw3.h> class MyWindow { private: GLFWwindow * windowHandle; int windowWidth; int windowHeight; const char * windowTitle; public: MyWindow(int windowWidth, int windowHeight, const char * windowTitle); ~MyWindow(); GLFWwindow * getWindowHandle(); void createWindow(); void MyWindow::destroyWindow(); }; MyWindow.cpp
      #include "MyWindow.h" MyWindow::MyWindow(int windowWidth, int windowHeight, const char * windowTitle) { this->windowHandle = NULL; this->windowWidth = windowWidth; this->windowWidth = windowWidth; this->windowHeight = windowHeight; this->windowTitle = windowTitle; glfwInit(); } MyWindow::~MyWindow() { } GLFWwindow * MyWindow::getWindowHandle() { return this->windowHandle; } void MyWindow::createWindow() { // Use OpenGL 3.3 and GLSL 3.3 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // Limit backwards compatibility glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Prevent resizing window glfwWindowHint(GLFW_RESIZABLE, GL_FALSE); // Create window this->windowHandle = glfwCreateWindow(this->windowWidth, this->windowHeight, this->windowTitle, NULL, NULL); glfwMakeContextCurrent(this->windowHandle); } void MyWindow::destroyWindow() { glfwTerminate(); } MyShapes.h
      #pragma once #include <glad\glad.h> #include <GLFW\glfw3.h> class MyShapes { public: MyShapes(); ~MyShapes(); GLuint & drawTriangle(float coordinates[]); }; MyShapes.cpp
      #include "MyShapes.h" MyShapes::MyShapes() { } MyShapes::~MyShapes() { } GLuint & MyShapes::drawTriangle(float coordinates[]) { GLuint vertexBufferObject{}; GLuint vertexArrayObject{}; // Create a VAO glGenVertexArrays(1, &vertexArrayObject); glBindVertexArray(vertexArrayObject); // Send vertices to the GPU glGenBuffers(1, &vertexBufferObject); glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject); glBufferData(GL_ARRAY_BUFFER, sizeof(coordinates), coordinates, GL_STATIC_DRAW); // Dertermine the interpretation of the array buffer glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float), (void *)0); glEnableVertexAttribArray(0); // Unbind the buffers glBindBuffer(GL_ARRAY_BUFFER, 0); glBindVertexArray(0); return vertexArrayObject; } MyFileHandler.h
      #pragma once #include <cstdio> #include <cstdlib> class MyFileHandler { private: const char * fileName; unsigned long fileSize; void setFileSize(); public: MyFileHandler(const char * fileName); ~MyFileHandler(); unsigned long getFileSize(); const char * readFile(); }; MyFileHandler.cpp
      #include "MyFileHandler.h" MyFileHandler::MyFileHandler(const char * fileName) { this->fileName = fileName; this->setFileSize(); } MyFileHandler::~MyFileHandler() { } void MyFileHandler::setFileSize() { FILE * fileHandle = NULL; fopen_s(&fileHandle, this->fileName, "rb"); fseek(fileHandle, 0L, SEEK_END); this->fileSize = ftell(fileHandle); rewind(fileHandle); fclose(fileHandle); return; } unsigned long MyFileHandler::getFileSize() { return (this->fileSize); } const char * MyFileHandler::readFile() { char * buffer = (char *)malloc((this->fileSize)+1); FILE * fileHandle = NULL; fopen_s(&fileHandle, this->fileName, "rb"); fread(buffer, this->fileSize, sizeof(char), fileHandle); fclose(fileHandle); buffer[this->fileSize] = '\0'; return buffer; } VertexShader.glsl
      #version 330 core layout (location = 0) vec3 VertexPositions; void main() { gl_Position = vec4(VertexPositions, 1.0f); } FragmentShader.glsl
      #version 330 core out vec4 FragmentColor; void main() { FragmentColor = vec4(1.0f, 0.0f, 0.0f, 1.0f); } I am attempting to create a simple engine/graphics utility using some object-oriented paradigms. My first goal is to get some output from my engine, namely, a simple red triangle.
      For this goal, the MyShapes class will be responsible for defining shapes such as triangles, polygons etc. Currently, there is only a drawTriangle() method implemented, because I first wanted to see whether it works or not before attempting to code other shape drawing methods.
      The constructor of the MyEngine class creates a GLFW window (GLAD is also initialized here to load all OpenGL functionality), and the myEngine.run() method in Main.cpp is responsible for firing up the engine. In this run() method, the shaders get loaded from files via the help of my FileHandler class. The vertices for the triangle are processed by the myShapes.drawTriangle() method where a vertex array object, a vertex buffer object and vertrex attributes are set for this purpose.
      The while loop in the run() method should be outputting me the desired red triangle, but all I get is a grey window area. Why?
      Note: The shaders are compiling and linking without any errors.
      (Note: I am aware that this code is not using any good software engineering practices (e.g. exceptions, error handling). I am planning to implement them later, once I get the hang of OpenGL.)

       
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
    • By Tchom
      Hey devs!
       
      I've been working on a OpenGL ES 2.0 android engine and I have begun implementing some simple (point) lighting. I had something fairly simple working, so I tried to get fancy and added color-tinting light. And it works great... with only one or two lights. Any more than that, the application drops about 15 frames per light added (my ideal is at least 4 or 5). I know implementing lighting is expensive, I just didn't think it was that expensive. I'm fairly new to the world of OpenGL and GLSL, so there is a good chance I've written some crappy shader code. If anyone had any feedback or tips on how I can optimize this code, please let me know.
       
      Vertex Shader
      uniform mat4 u_MVPMatrix; uniform mat4 u_MVMatrix; attribute vec4 a_Position; attribute vec3 a_Normal; attribute vec2 a_TexCoordinate; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { v_Position = vec3(u_MVMatrix * a_Position); v_TexCoordinate = a_TexCoordinate; v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); gl_Position = u_MVPMatrix * a_Position; } Fragment Shader
      precision mediump float; uniform vec4 u_LightPos["+numLights+"]; uniform vec4 u_LightColours["+numLights+"]; uniform float u_LightPower["+numLights+"]; uniform sampler2D u_Texture; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { gl_FragColor = (texture2D(u_Texture, v_TexCoordinate)); float diffuse = 0.0; vec4 colourSum = vec4(1.0); for (int i = 0; i < "+numLights+"; i++) { vec3 toPointLight = vec3(u_LightPos[i]); float distance = length(toPointLight - v_Position); vec3 lightVector = normalize(toPointLight - v_Position); float diffuseDiff = 0.0; // The diffuse difference contributed from current light diffuseDiff = max(dot(v_Normal, lightVector), 0.0); diffuseDiff = diffuseDiff * (1.0 / (1.0 + ((1.0-u_LightPower[i])* distance * distance))); //Determine attenuatio diffuse += diffuseDiff; gl_FragColor.rgb *= vec3(1.0) / ((vec3(1.0) + ((vec3(1.0) - vec3(u_LightColours[i]))*diffuseDiff))); //The expensive part } diffuse += 0.1; //Add ambient light gl_FragColor.rgb *= diffuse; } Am I making any rookie mistakes? Or am I just being unrealistic about what I can do? Thanks in advance
    • By yahiko00
      Hi,
      Not sure to post at the right place, if not, please forgive me...
      For a game project I am working on, I would like to implement a 2D starfield as a background.
      I do not want to deal with static tiles, since I plan to slowly animate the starfield. So, I am trying to figure out how to generate a random starfield for the entire map.
      I feel that using a uniform distribution for the stars will not do the trick. Instead I would like something similar to the screenshot below, taken from the game Star Wars: Empire At War (all credits to Lucasfilm, Disney, and so on...).

      Is there someone who could have an idea of a distribution which could result in such a starfield?
      Any insight would be appreciated
  • Popular Now