• 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
Yours3!f

OpenGL
uniforms

10 posts in this topic

Hi,

I'm trying to move to using the new opengl layout qualifiers. I almost got everything working, however I ran into a small problem.
When I add the overlay_color uniform, I can't set it using the glUniform3fv(), and I don't know why. All the other uniforms, attributes, samplers can be set, except this one... The shader still compiles, links and validates successfully, and no warning is shown that would indicate anything.
When I try to set the overlay_color (using glUniform3fv) I get GL_INVALID_OPERATION. I checked the specs, but I can't figure out what I'm missing, because:
-the program object is set, and valid
-the variable's size matches the glUniform function
-the location (I think) is valid, and not -1
-the count is 1

here's the shader:
[CODE]

[ vertex shader ]

#version 420 core

layout(location=0) uniform mat4 mvp;

layout(location=0) in vec4 in_vertex;
layout(location=5) in vec2 in_texture;

out cross_shader_data
{
vec2 tex_coord;
} o;

out vec4 color;

void main()
{
o.tex_coord = in_texture;
gl_Position = mvp * in_vertex;
}

[ pixel shader ]

#version 420 core

layout(location=1,binding=0) uniform sampler2D texture0;
layout(location=2) uniform vec3 overlay_color;

in cross_shader_data
{
vec2 tex_coord;
} i;

out vec4 color;

void main()
{
color = texture(texture0, i.tex_coord) + vec4(overlay_color, 1);
}
[/CODE]

here's how I'm passing the values:
[CODE]
glUseProgram( this->shader );
vec3 overlay_color = {{ 1, 0, 0 }};
glUniform3fv( 2, 1, &overlay_color.v[0] );
glUniformMatrix4fv( 0, 1, false,
&o->ppl->get_model_view_projection_matrix( o->ppl ).m[0].v[0] );
[/CODE]
0

Share this post


Link to post
Share on other sites
[quote name='Aks9' timestamp='1351862905' post='4996521']
Why do you need this feature? If it is for the learning sake only, please wait until stable drivers release.
There are several sources of the problem.

What drivers are you using? GL_ARB_explicit_uniform_location is the part of GLSL 4.3 core spec, not 4.2. If you are using NV 310.xx drivers, then there could be a bug, since they are in a beta phase. If you are using previous releases, then you should check whether the extension is supported and probably enable it explicitly in GLSL (if it is supported).

I guess you don't have support GL_ARB_explicit_uniform_location and the reason it works for the first uniform is accidental correspondence with compiler's associated locations. NV uses alphabetical order of names. So, locations are as follows:
0 - mvp
2 - texture0
1 - overlay_color

Before trying to use some new feature check if it is presented and read specification to understand how it works. ;)
[/quote]

:( I'm on AMD with only OGL4.2 drivers... I guess I'll have to stick with glGetUniformLocation...
as for the why: I just wanted to get rid of keeping track of uniform locations. It's not that cumbersome, but it would be great if I didn't have to.
I guess for the rest you're right, I just accidentally got the uniform locations right. Well, thank you for clarifying the situation. I just thought this was available since gl 3.1
1

Share this post


Link to post
Share on other sites
[quote name='Yours3!f' timestamp='1351934185' post='4996807']
I'm on AMD with only OGL4.2 drivers... I guess I'll have to stick with glGetUniformLocation...
as for the why: I just wanted to get rid of keeping track of uniform locations. It's not that cumbersome, but it would be great if I didn't have to.
[/quote]
T thought you are using NV hardware, since only NV currently has GL 4.3 support.

Well, I don't agree that getting uniforms' (or attributes') location is cumbersome, especially because that should be done only once, during the initialization phase.
I'm using class-wrapper for each shaders. Uniforms and attributes locations are attributes of the instance, and they are set in the Init() function (at the same place where I load and compile shaders, and link the program). After that, I just call appropriate function (method) of the particular object to set values. It cannot be easier.

Another remark: Setting attribute location is also not correct in your code, because you are wasting 4 locations.
layout([b]location=0[/b]) in [b]vec4[/b] in_vertex;
layout([b]location=5[/b]) in [b]vec2[/b] in_texture;

In the unpacked format, both vec2 and vec4 consumes just one location. In your case, layout is like follows:
location 0: | in_vertex.x | in_vertex.y | in_vertex.z | in_vertex.w |
location 1: | < empty > | < empty > | < empty > | < empty > |
location 2: | < empty > | < empty > | < empty > | < empty > |
location 3: | < empty > | < empty > | < empty > | < empty > |
location 4: | < empty > | < empty > | < empty > | < empty > |
location 5: | in_texture.s | in_texture.t | < empty > | < empty > |

As you can see, there is a lot of wasted space. So, if you don't have a particular reason to define layout and reuse it across multiple shader-objects, It would be wiser to just let compiler do it, or read specifications to see how it actually works.
Happy coding! [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]
1

Share this post


Link to post
Share on other sites
[quote name='Aks9' timestamp='1351942489' post='4996828']
[quote name='Yours3!f' timestamp='1351934185' post='4996807']
I'm on AMD with only OGL4.2 drivers... I guess I'll have to stick with glGetUniformLocation...
as for the why: I just wanted to get rid of keeping track of uniform locations. It's not that cumbersome, but it would be great if I didn't have to.
[/quote]
T thought you are using NV hardware, since only NV currently has GL 4.3 support.

Well, I don't agree that getting uniforms' (or attributes') location is cumbersome, especially because that should be done only once, during the initialization phase.
I'm using class-wrapper for each shaders. Uniforms and attributes locations are attributes of the instance, and they are set in the Init() function (at the same place where I load and compile shaders, and link the program). After that, I just call appropriate function (method) of the particular object to set values. It cannot be easier.

Another remark: Setting attribute location is also not correct in your code, because you are wasting 4 locations.
layout([b]location=0[/b]) in [b]vec4[/b] in_vertex;
layout([b]location=5[/b]) in [b]vec2[/b] in_texture;

In the unpacked format, both vec2 and vec4 consumes just one location. In your case, layout is like follows:
location 0: | in_vertex.x | in_vertex.y | in_vertex.z | in_vertex.w |
location 1: | < empty > | < empty > | < empty > | < empty > |
location 2: | < empty > | < empty > | < empty > | < empty > |
location 3: | < empty > | < empty > | < empty > | < empty > |
location 4: | < empty > | < empty > | < empty > | < empty > |
location 5: | in_texture.s | in_texture.t | < empty > | < empty > |

As you can see, there is a lot of wasted space. So, if you don't have a particular reason to define layout and reuse it across multiple shader-objects, It would be wiser to just let compiler do it, or read specifications to see how it actually works.
Happy coding! [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]
[/quote]

I know it should be done only once, but I just have't came up with a system to do it :)
Thanks, I wasn't aware of this behaviour of the attributes, I'll fix this.
0

Share this post


Link to post
Share on other sites
[quote name='Hodgman' timestamp='1352024330' post='4997123']
a more accurate API would instead expose the idea of there being a register bank in which values can be stored, and of shader programs that do not store uniform values as properties.
Under this hardware design, if two shader programs use the same uniform layout, and require the same values, then no work needs to be done when switching programs
[/quote]

It's interesting to note that the older ARB assembly extensions exposed this kind of setup (in an interesting manner, with both "local" and "env" parameters), so in many respects GLSL was actually quite a step backwards from even that (having to link vertex and fragment shaders into a program object was another example).

I [i]believe[/i] that even with explicit uniform location GLSL [i]still[/i] doesn't expose a way to just set a uniform once and have it available to all programs, short of using UBOs.

It's a case of: unless one has been exposed to something cleaner, neater and simpler, one really doesn't get the full appreciation of just how nasty, messy and awkward the way one is currently doing stuff really is. Edited by mhagain
2

Share this post


Link to post
Share on other sites
[quote name='mhagain' timestamp='1352110679' post='4997516']
I [i]believe[/i] that even with explicit uniform location GLSL [i]still[/i] doesn't expose a way to just set a uniform once and have it available to all programs, short of using UBOs.
[/quote]
I don't see what the problem is. Uniforms are the part of the program's state. They shouldn't be visible outside of the program and their state remains until they are explicitly changed for the particular program. There is nothing wrong with that. Explicit uniform location has nothing with sharing uniforms. It has the same purpose as explicit attrib. location. If uniforms have to be shared among multiple programs that's where UBOs should be used.
0

Share this post


Link to post
Share on other sites
[quote name='Aks9' timestamp='1352143204' post='4997685']
I don't see what the problem is. Uniforms are the part of the program's state. They shouldn't be visible outside of the program and their state remains until they are explicitly changed for the particular program. There is nothing wrong with that. Explicit uniform location has nothing with sharing uniforms. It has the same purpose as explicit attrib. location. If uniforms have to be shared among multiple programs that's where UBOs should be used.
[/quote]

Well that's more or less exactly what I said, if erring a little on the side of "the way GL does it is best because it's the way GL does it", but I'd suggest that you re-read Hodgman's post above for a description of what's wrong with it.

Now, I'm not going split hairs over which is the best approach from an API standpoint; one can easily produce test cases in which either approach can be shown to be preferable to the other and in fact my own opinion is that ARB assembly's concept of "local" and "env" parameters is close to what I'd consider ideal, and which unfortunately neither of the current high-level languages in either GL or D3D can cleanly replicate.

Of course you can write your own layer of additional boilerplate to handle all of it, but that's kinda missing the point of using an API, methinks, as it's functionality that each API should be providing.
1

Share this post


Link to post
Share on other sites
[quote name='mhagain' timestamp='1352149551' post='4997726']
Now, I'm not going split hairs over which is the best approach from an API standpoint; one can easily produce test cases in which either approach can be shown to be preferable to the other and in fact my own opinion is that ARB assembly's concept of "local" and "env" parameters is close to what I'd consider ideal, and which unfortunately neither of the current high-level languages in either GL or D3D can cleanly replicate.
[/quote]

I'm not sure the hardware would be happy with that anyway; given that all loads basically go via a L1/L2 cache system the idea of a 'register' across shaders is moot anyway.
Given the requirements for managing data upload the idea of being able to upload one bit of memory and reuse it doesn't seem like a great idea either.

Approiately sized and split cbuffer/UBOs where you can control the size and upload frequency is probably the best fit for the current hardware and will continue to be for a little while yet.
0

Share this post


Link to post
Share on other sites
[quote name='Aks9' timestamp='1352143204' post='4997685']
I don't see what the problem is. Uniforms are the part of the program's state.[/quote]That's the problem. This was an accurate reflection of some pixel shader hardware in 2005, but is now not at all reflective of actual GPU hardware. In order for GL to provide you with the abstraction that uniforms are part of a program's state, the GL driver is forced to emulate this behavior, [b][i]which is extremely costly[/i][/b]. There's no need for GL to emulate the behavior of half a decade old hardware any more.
[quote]Explicit uniform location has nothing with sharing uniforms.[/quote]In D3D it can be leveraged to reduce the cost of setting uniforms. D3D9's abstractions don't tie uniform values and programs together like GL does ([i]i.e. when setting a uniform in D3D9, the value persists in that 'slot' until it's set to another value, regardless of which program is set[/i]), which allows a graphics engine to greatly simplify the process of setting uniform values.
If the previous draw-call has set 50 3x4 bone matrices in registers #42-192, and the current draw-call (which uses a different program) requires the same array of matrices in the same registers, then the engine can detect that condition with very little effort ([i]e.g. a single comparison[/i]) and do zero work, relying on the fact that the GPU will already contain the correct uniform values.

In GL, because you're dealing with an emulation layer instead of a valid abstraction, the program is required to set all 50 matrices on [i]both[/i] programs regardless, and then the GL driver is forced to perform 150 vec4 vs vec4 value comparisons in order to determine whether the new uniform values are redundant or not, and whether it should send them to the GPU registers.

The UBO abstraction is exactly the same as the D3D9 abstraction, except that multiple register banks of different sizes can be exist and/or be bound at a time, instead of there being a single global register bank. [i]e.g.The D3D9 behavior could be emulated on GL3/D3D10 by creating a single global UBO, but that wouldn't be useful ;)[/i]

For SM3 GPUs, when comparing GL2 and D3D9, D3D9 allows a rendering engine to be several orders of magnitudes more efficient when it comes to managing uniform values.
For SM4/5 GPU's, the same is true for GL2 vs GL3 with UBOs.
[quote]If uniforms have to be shared among multiple programs that's where UBOs should be used.[/quote]If you're targeting GL3 or GL4, then GL2's way of managing uniforms should be entirely discarded, and GL3's UBO's should be used in all circumstances - because the UBO abstraction actually maps to the SM4/5 GPU hardware. Edited by Hodgman
2

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