Sign in to follow this  
nitro404

OpenGL [SDL] Super slow framerate on Windows 7, GLEW shaders unavailable

Recommended Posts

Hello!

I've been working on a project off and on in SDL for a number of months now, and I've had an issue from the start that I recently had some time to try and debug. I've been developing on Windows XP until this past week, so it was not really an issue until now.

Basically, my SDL bases game works perfectly fine on any Windows XP machine (ie. normal frame rate, shaders work no problem), but I initially noticed that if I ran the executable on Windows 7, the frame rate would only be 10-15 for no reason (on super high-end machines, ie. Phenom II X6 / 5970) but this was strictly a Windows 7 issue as indicated by testing on several different machines. Upon further investigation I realized that if I run the game from within Visual Studio 2008 on a Windows 7 machine it works perfectly (ie. 7000+ FPS w/o vsync), but as soon as I ran it from the executable instead, the frame rate would once again be between 10 and 15, and if shaders were being used via GLEW, the program would simply exit because GLEW 2.0 was unavailable.

tldr; SDL OpenGL game, works fine on XP, on Win7 works fine in VS2008 but EXE limited to 10 fps and shaders wont work

Honestly not sure what the issue could possibly be and has been baffling me for some time. If anyone has any suggestions or input, it would be greatly appreciated. It almost seems like SDL is somehow switching to software mode or some limited version of OpenGL. Also worth mentioning that the only things being rendered is some text (generated and rendered via lists) and a very simple skybox with 1024x1024 textures for each side.

My game is using SDLmain and a number of libraries, including:
SDL
SDL_ttf
GLEW
FreeImage
Qt
FMOD Ex
FBX SDK
Bullet Physics

Thanks for reading. Some code, if it helps any:

Main.cpp:
[CODE]
#include "Game.h"
int main(int argc, char * argv[]) {
Game * game = new Game();
if(!game->init()) { return -1; }
game->run();
delete game;
return 0;
}
[/CODE]

OpenGL Setup:
[CODE]
bool Game::init() {
if(m_initialized) { return false; }
settings->load();
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_JOYSTICK) == -1) { return false; }
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, settings->verticalSync ? 1 : 0);
m_graphics = SDL_SetVideoMode(settings->windowWidth, settings->windowHeight, 0, SDL_OPENGL | (settings->fullScreen ? SDL_FULLSCREEN : 0));
SDL_WM_SetCaption("Game", NULL);
QString iconPath;
iconPath.append(QString("%1/Icons/Block.bmp").arg(settings->dataDirectoryName));
QByteArray iconPathBytes = iconPath.toLocal8Bit();
m_icon = SDL_LoadBMP(iconPathBytes.data());
SDL_WM_SetIcon(m_icon, NULL);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glDepthFunc(GL_LEQUAL);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glMatrixMode(GL_MODELVIEW);
glViewport(0, 0, settings->windowWidth, settings->windowHeight);
if(glewInit() != GLEW_OK) { return false; }
if(!GLEW_VERSION_2_0) { return false; }

etc.
[/CODE]

Game Loop:
[CODE]
void Game::run() {
if(!m_initialized) { return; }
m_running = true;
SDL_Event event;
static unsigned int lastTime = SDL_GetTicks();
unsigned int currentTime = SDL_GetTicks();
do {
if(SDL_PollEvent(&event)) {
switch(event.type) {
case SDL_KEYDOWN:
if(!console->isActive()) {
menu->handleInput(event);
}
if(!menu->isActive()) {
console->handleInput(event);
}
break;
case SDL_MOUSEMOTION:
if(!console->isActive() &&
!menu->isActive() &&
SDL_GetAppState() & SDL_APPMOUSEFOCUS &&
SDL_GetAppState() & SDL_APPINPUTFOCUS &&
SDL_GetAppState() & SDL_APPACTIVE) {
camera->handleInput(event);
}
break;
case SDL_QUIT:
m_running = false;
break;
default:
break;
}
}
if(m_running) {
currentTime = SDL_GetTicks();
update(currentTime - lastTime);
draw();
lastTime = currentTime;
}
} while(m_running);
}
[/CODE]

Share this post


Link to post
Share on other sites
[code]if(SDL_PollEvent(&event))[/code]

Should be:

[code]while ( SDL_PollEvent( &event ) )[/code]

It's likely that your event queue accumulates more and and more windows events until your game slows down to a crawl -- you need to process all of the window messages between each frame, not just one per frame. (Not sure if this will fix your problem, but it will certainly help...)

Share this post


Link to post
Share on other sites
Oh dear, I feel ashamed for implementing that wrong. Thanks for the reply! Although this did not fix my previous issues (slow framerate, shaders unsupported), it did fix my input handling and bizarre behaviours I was experiencing with my camera which I had yet to solve, so thanks!

Still looking for a solution, though. I just can't figure what's so different with the execution of the game between being run from Visual Studio 2008 vs. from the compiled release executable.

Share this post


Link to post
Share on other sites
Not as far as I know, I'm using glLists for my SkyBox, and standard OpenGL stuff for the rest, see code below. The only strange thing I'm doing is using SDL_ttf which uses SDL_Surface to blit text which I convert to an OpenGL texture. Irregardless, I don't think any of this should be an issue if it works perfectly fine from Visual Studio 2008, right?

Edit: Furthermore, there are no problems on Windows XP when running from either VS2008 or EXE. So why is it such a problem on Windows 7? I'm using platform independent libraries (ie. no STL), so I'm still completely baffled.

SkyBox Load:
[code]
bool SkyBox::load() {
if(m_loaded) { return true; }

for(int i=0;i<6;i++) {
m_textures[i] = Game::resources->getTexture(m_textureNames[i]);
if(m_textures[i] == NULL) { return false; }
if(!m_textures[i]->load()) { return false; }
}

m_skyBoxList = glGenLists(6);

float width = (float) (m_textures[0]->getWidth() - 1) / (float) m_textures[0]->getWidth();

// left side
glNewList(m_skyBoxList, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(1 - width, width);
glVertex3d(-0.5, 0.5, 0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(-0.5, -0.5, 0.5);
glTexCoord2d(width, 1 - width);
glVertex3d(-0.5, -0.5, -0.5);
glTexCoord2d(width, width);
glVertex3d(-0.5, 0.5, -0.5);
glEnd();
glEndList();

// right side
glNewList(m_skyBoxList + 1, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(1 - width, width);
glVertex3d(0.5, 0.5, -0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(0.5, -0.5, -0.5);
glTexCoord2d(width, 1 - width);
glVertex3d(0.5, -0.5, 0.5);
glTexCoord2d(width, width);
glVertex3d(0.5, 0.5, 0.5);
glEnd();
glEndList();

// front side
glNewList(m_skyBoxList + 2, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(1 - width, width);
glVertex3d(-0.5, 0.5, -0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(-0.5, -0.5, -0.5);
glTexCoord2d(width, 1 - width);
glVertex3d(0.5, -0.5, -0.5);
glTexCoord2d(width, width);
glVertex3d(0.5, 0.5, -0.5);
glEnd();
glEndList();

// back side
glNewList(m_skyBoxList + 3, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(1 - width, width);
glVertex3d(0.5, 0.5, 0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(0.5, -0.5, 0.5);
glTexCoord2d(width, 1 - width);
glVertex3d(-0.5, -0.5, 0.5);
glTexCoord2d(width, width);
glVertex3d(-0.5, 0.5, 0.5);
glEnd();
glEndList();

// top side
glNewList(m_skyBoxList + 4, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(width, 1 - width);
glVertex3d(-0.5, 0.5, 0.5);
glTexCoord2d(width, width);
glVertex3d(-0.5, 0.5, -0.5);
glTexCoord2d(1 - width, width);
glVertex3d(0.5, 0.5, -0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(0.5, 0.5, 0.5);
glEnd();
glEndList();

// bottom side
glNewList(m_skyBoxList + 5, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2d(width, 1 - width);
glVertex3d(-0.5, -0.5, -0.5);
glTexCoord2d(width, width);
glVertex3d(-0.5, -0.5, 0.5);
glTexCoord2d(1 - width, width);
glVertex3d(0.5, -0.5, 0.5);
glTexCoord2d(1 - width, 1 - width);
glVertex3d(0.5, -0.5, -0.5);
glEnd();
glEndList();

m_loaded = true;

return true;
}
[/code]

SkyBox Draw:
[code]
void SkyBox::draw() {
if(!m_loaded) { return; }

glDisable(GL_DEPTH_TEST);

glLoadIdentity();

glRotated(Game::camera->getRotation().x, 1, 0, 0);
glRotated(Game::camera->getRotation().y, 0, 1, 0);

for(int i=0;i<6;i++) {
m_textures[i]->activate();
glCallList(m_skyBoxList + i);
}

glEnable(GL_DEPTH_TEST);
}
[/code]

Game Draw:
[code]
void Game::draw() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// set up 3d rendering
glEnable(GL_TEXTURE_2D);
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(70.0f, (GLfloat) settings->windowWidth / (GLfloat) settings->windowHeight, 0.1f, 10000.0f);
glMatrixMode(GL_MODELVIEW);

// render skybox
if(skyBox != NULL) {
skyBox->draw();
}

// render world
if(mainShader != NULL) { mainShader->activate(); }

glPushMatrix();
camera->setup();

glScalef(100, 100, 100);

glBegin(GL_POLYGON);

// left
glVertex3f(-1.0f, 0.0f, 0.0f);
glVertex3f(-1.0f, 0.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);

// right
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(0.0f, -1.0f, 0.0f);
glVertex3f(0.0f, -1.0f, -1.0f);
glVertex3f(0.0f, 0.0f, -1.0f);

// front
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(-1.0f, 0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glVertex3f(0.0f, -1.0f, 0.0f);

// back
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(-1.0f, 0.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(0.0f, -1.0f, -1.0f);

// top
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(0.0f, 0.0f, -1.0f);
glVertex3f(-1.0f, 0.0f, -1.0f);
glVertex3f(-1.0f, 0.0f, 0.0f);

// bottom
glVertex3f(0.0f, 0.0f, 0.0f);
glVertex3f(0.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);

glEnd();
glPopMatrix();

if(mainShader != NULL) { mainShader->deactivate(); }

// set up 2d rendering
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, settings->windowWidth, settings->windowHeight, 0);

// render hud / gui elements
displayFPS();
menu->draw();
console->draw();

SDL_GL_SwapBuffers();
}
[/code]

Font Draw / Load:
[code]
void Font::drawTextHelper(int x, int y, const char * text) const {
if(!m_loaded) { return; }

glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);

glBindTexture(GL_TEXTURE_2D, m_texture);

glMatrixMode(GL_MODELVIEW);
glPushMatrix();

glLoadIdentity();

glTranslated(x, y, 0);
glListBase(m_font - 32);
glCallLists(strlen(text), GL_BYTE, text);

glPopMatrix();
}

bool Font::load() {
if(m_loaded) { return true; }

QString fontPath = QString("%1/Fonts/%2").arg(Game::settings->dataDirectoryName).arg(m_fileName);

QFileInfo fontFile(fontPath);
if(!fontFile.exists()) { return false; }

QByteArray bytes = fontPath.toLocal8Bit();

TTF_Font * fontData;
if(!(fontData = TTF_OpenFont(bytes.data(), m_size))) {
return false;
}

SDL_Color colour = {255, 255, 255, 255};

SDL_Surface * character;
QVector characters;
int maxWidth = -1;
int maxHeight = -1;
char data[2];
data[1] = '\0';
for(int i=0;i<128;i++ ) {
data[0] = (char) (i + 32);
character = TTF_RenderText_Blended(fontData, data, colour);
characters.push_back(character);
if(maxWidth < 0 || maxWidth < character->w) { maxWidth = character->w; }
if(maxHeight < 0 || maxHeight < character->h) { maxHeight = character->h; }
}

m_horizontalSpacing = maxWidth;
m_verticalSpacing = maxHeight;

int width = 1, tempWidth = maxWidth * 16;
int height = 1, tempHeight = maxHeight * 8;
while(width < tempWidth) { width *= 2; }
while(height < tempHeight) { height *= 2; }

SDL_Surface * temp = SDL_CreateRGBSurface(0, width, height, 32,
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
0xff000000, 0x00ff0000, 0x0000ff00, 0x000000ff
#else
0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
#endif
);

SDL_Rect sourceArea, destArea;
int x = 0;
int y = 0;
for(int i=0;i<128;i++) {
sourceArea.x = 0;
sourceArea.y = 0;
sourceArea.w = characters[i]->w;
sourceArea.h = characters[i]->h;

destArea.x = maxWidth * x;
destArea.y = maxHeight * y;
destArea.w = characters[i]->w;
destArea.h = characters[i]->h;

SDL_SetAlpha(characters[i], 0, 0);
SDL_BlitSurface(characters[i], &sourceArea, temp, &destArea);

x++;
if(x == 16) {
x = 0;
y++;
}
}

glGenTextures(1, &m_texture);
glBindTexture(GL_TEXTURE_2D, m_texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, temp->w, temp->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, temp->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);

m_font = glGenLists(128);

x = 0;
y = 0;
float w = (float) maxWidth / (float) (temp->w);
float h = (float) maxHeight / (float) (temp->h);
for(int i=0;i<128;i++) {

glNewList(m_font + i, GL_COMPILE);

glBegin(GL_QUADS);
glTexCoord2f((w * x), ((h * y))); glVertex2i(0, 0);
glTexCoord2f((w * x) + w, ((h * y))); glVertex2i(maxWidth, 0);
glTexCoord2f((w * x) + w, ((h * y) + h)); glVertex2i(maxWidth, maxHeight);
glTexCoord2f((w * x), ((h * y) + h)); glVertex2i(0, maxHeight);
glEnd();

glTranslated(maxWidth, 0, 0);

glEndList();

x++;
if(x == 16) {
x = 0;
y++;
}
}

for(int i=0;i<128;i++) {
SDL_FreeSurface(characters[i]);
}
SDL_FreeSurface(temp);

m_loaded = true;

return true;
}
[/code]

Share this post


Link to post
Share on other sites
Found the solution to all my issues finally, after consulting some friends. Turns out Visual Studio 2008 on Windows 7 would use the operating system's version of OpenGL, and when I ran it from the EXE it used the local OpenGL32.dll which was either out of date, or built for the wrong platform. So, removing this DLL fixed all framerate issues, and now runs no problem after defaulting to the operating system's OpenGL32.dll. Hopefully this helps anyone else who runs into this issue!

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  

  • Announcements

  • Forum Statistics

    • Total Topics
      628326
    • Total Posts
      2982086
  • 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