Sign in to follow this  

OpenGL texture mapping really slow

Recommended Posts

bradbobak    1825
Hi, I'm working on an opengl engine and for some reason, on my system, it seems that texture mapping is horribly slow.

I'm using ubuntu 64-bit, with ati's own drivers across two monitors.

I've modified a nehe example tutorial to make it as basic as I could to illustrate my problem.

(when I disable double buffering in my main app, I can see the texture rendering line-by-line (it draws maybe 5 lines per second)).

The modified tutorial prints out
Got Doublebuffer Visual!
glX-Version 1.4
Depth 24
Congrats, you have Direct Rendering!

Possibly the problem is that I'm driving 2 different monitors with one video card, causing texture mapping to happen on the cpu side of things?

Anyhow, here is the modified tutorial (stripped down as much as I could). It takes about 30 seconds to texture map a 512x512 texture to a simple QUAD.


* This code was created by Jeff Molofee '99
* (ported to Linux/GLX by Mihael Vrbanec '00)
* [edited for brevity]
* (modified by me to illustrate a test case)

#include <memory.h>

#include <stdio.h>
#include <GL/glx.h>
#include <GL/gl.h>

/* stuff about our window grouped together */
typedef struct {
Display *dpy;
int screen;
Window win;
GLXContext ctx;
XSetWindowAttributes attr;
int x, y;
unsigned int width, height;
unsigned int depth;
} GLWindow;

static int attrListDbl[] = { GLX_RGBA, GLX_DOUBLEBUFFER,
None };

GLWindow GLWin;

/* function called when our window is resized (should only happen in window mode) */
void resizeGLScene(unsigned int width, unsigned int height)
glViewport(0, 0, width, height);

// <added by me, this is the generated texture I am rendering>
int tex;

/* general OpenGL initialization function */
int initGL(GLvoid)
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
/* we use resizeGLScene once to set up our initial perspective */
resizeGLScene(GLWin.width, GLWin.height);

// <my additions for texture mapping setup>

// initial buffer to copy to texture
int size = 512;
unsigned zeros[size * size];
memset(zeros, 0, size * size * 4);

// make a red square
int xct, yct;
for (yct = 50; yct < 100; ++yct)
for (xct = 50; xct < 100; ++xct)
zeros[yct * size + xct] = 0x000000ff;

glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, size, size, 1,


return True;

/* Here goes our drawing code */
int drawGLScene(GLvoid)

glFrustum(-1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 5.0f);


glBindTexture(GL_TEXTURE_2D, tex);
glColor3f(0.5f, 0.5f, 1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, 1.0f, -2.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, -2.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, -2.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, -2.0f);
return True;

/* this function creates our window and sets it up properly */
/* FIXME: bits is currently unused */
Bool createGLWindow(char* title, int width, int height, int bits)
XVisualInfo *vi;
Colormap cmap;
int dpyWidth, dpyHeight;
int i;
int glxMajorVersion, glxMinorVersion;
Window winDummy;
unsigned int borderDummy;

/* set best mode to current */
/* get a connection */
GLWin.dpy = XOpenDisplay(0);
GLWin.screen = DefaultScreen(GLWin.dpy);

vi = glXChooseVisual(GLWin.dpy, GLWin.screen, attrListDbl);
if (vi == NULL)
return 0;
printf("Got Doublebuffered Visual!\n");
glXQueryVersion(GLWin.dpy, &glxMajorVersion, &glxMinorVersion);
printf("glX-Version %d.%d\n", glxMajorVersion, glxMinorVersion);
/* create a GLX context */
GLWin.ctx = glXCreateContext(GLWin.dpy, vi, 0, GL_TRUE);
/* create a color map */
cmap = XCreateColormap(GLWin.dpy, RootWindow(GLWin.dpy, vi->screen),
vi->visual, AllocNone);
GLWin.attr.colormap = cmap;
GLWin.attr.border_pixel = 0;

/* create a window in window mode*/
GLWin.attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask |
StructureNotifyMask; = XCreateWindow(GLWin.dpy, RootWindow(GLWin.dpy, vi->screen),
0, 0, width, height, 0, vi->depth, InputOutput, vi->visual,
CWBorderPixel | CWColormap | CWEventMask, &GLWin.attr);
/* connect the glx-context to the window */
glXMakeCurrent(GLWin.dpy,, GLWin.ctx);
XGetGeometry(GLWin.dpy,, &winDummy, &GLWin.x, &GLWin.y,
&GLWin.width, &GLWin.height, &borderDummy, &GLWin.depth);
printf("Depth %d\n", GLWin.depth);
if (glXIsDirect(GLWin.dpy, GLWin.ctx))
printf("Congrats, you have Direct Rendering!\n");
printf("Sorry, no Direct Rendering possible!\n");
return True;

int main(int argc, char **argv)
XEvent event;

createGLWindow("NeHe's Color Tutorial", 640, 480, 24);

for (;;)

return 0;

Any help will be appreciated.

Share this post

Link to post
Share on other sites
WiredCat    1452
first of all disable in every rendering instead set it after resizing window (resize gl window procedure)

glFrustum(-1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 5.0f);

rest of code seems to be fine

Share this post

Link to post
Share on other sites
szecs    2990
[quote]first of all disable in every rendering instead set it after resizing window (resize gl window procedure)[/quote]

Setting projection matrices in every frame is peanuts for the GPU.
I usually do so, because there can be a lot of post processes, HUDs etc.

Things that can hurt performance:
1. No graphics driver installed. Sounds trivial, but I run into the problem. I was disappointed how slow openGL is. Then i realized something is wrong with the driver, i updated it and bam! at least 200 times faster rendering (it was really about 200).

2. You use non power-of-too textures.

3. Other stuff... Maybe for some reason, your openGL switches to "software rendering" instead of hardware rendering. Try to google that, I don't know specifics about why this can happen. Edited by szecs

Share this post

Link to post
Share on other sites
WiredCat    1452
aa and one other thing with doublebuffered make sure you ste opengl window to doublebuffered i don't know how you initialize opengl window so there could be the problem

i create ogl window by this:

void __fastcall TFCOpenGL::TWORZ_GL()
angle = 0;
ppp = 0;
int pf;

dc = GetDC( FCOpenGL->Handle );
ZeroMemory( &pfd, sizeof( pfd));
pfd.nSize = sizeof( pfd);
pfd.nVersion = 1;
pfd.iPixelType = PFD_TYPE_RGBA;
pfd.cColorBits = 32;
pfd.cDepthBits = 32; pfd.cStencilBits = 8;
pfd.iLayerType = PFD_MAIN_PLANE;

pf = ChoosePixelFormat(dc, &pfd); /
SetPixelFormat(dc, pf, &pfd);
rc = wglCreateContext(dc);




and make sure that control on what you are displaying is doublebuffered too (*TWinControl)NAME->DoubleBuffered = true; ;] Edited by ___

Share this post

Link to post
Share on other sites
MichaelBarth    341
[quote name='bradbobak' timestamp='1338211294' post='4944001']
Well I've uninstalled the proprietary ati drivers and went to the open source ones and everything is working fine. Thanks for the replys.

A word on that, ATI drivers generally suck especially on Linux based system, and especially for OpenGL. This high resolution pack for a game uses OpenGL, and half of what was rendered when using ATI drivers, was white rectangles. The way to get it to work was go back to an old driver, 10.5 I believe. That's just in my experience anyway. I was actually doing some texture mapping on a sphere in OpenGL and it worked fine on my computer with a NVIDIA GPU, but when I went to two other computers that used ATI, I noticed a slowdown, and this is on Windows. I've just had really bad experiences with ATI, there really should be another company out there that makes GPUs

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By Zaphyk
      I am developing my engine using the OpenGL 3.3 compatibility profile. It runs as expected on my NVIDIA card and on my Intel Card however when I tried it on an AMD setup it ran 3 times worse than on the other setups. Could this be a AMD driver thing or is this probably a problem with my OGL code? Could a different code standard create such bad performance?
    • By Kjell Andersson
      I'm trying to get some legacy OpenGL code to run with a shader pipeline,
      The legacy code uses glVertexPointer(), glColorPointer(), glNormalPointer() and glTexCoordPointer() to supply the vertex information.
      I know that it should be using setVertexAttribPointer() etc to clearly define the layout but that is not an option right now since the legacy code can't be modified to that extent.
      I've got a version 330 vertex shader to somewhat work:
      #version 330 uniform mat4 osg_ModelViewProjectionMatrix; uniform mat4 osg_ModelViewMatrix; layout(location = 0) in vec4 Vertex; layout(location = 2) in vec4 Normal; // Velocity layout(location = 3) in vec3 TexCoord; // TODO: is this the right layout location? out VertexData { vec4 color; vec3 velocity; float size; } VertexOut; void main(void) { vec4 p0 = Vertex; vec4 p1 = Vertex + vec4(Normal.x, Normal.y, Normal.z, 0.0f); vec3 velocity = (osg_ModelViewProjectionMatrix * p1 - osg_ModelViewProjectionMatrix * p0).xyz; VertexOut.velocity = velocity; VertexOut.size = TexCoord.y; gl_Position = osg_ModelViewMatrix * Vertex; } What works is the Vertex and Normal information that the legacy C++ OpenGL code seem to provide in layout location 0 and 2. This is fine.
      What I'm not getting to work is the TexCoord information that is supplied by a glTexCoordPointer() call in C++.
      What layout location is the old standard pipeline using for glTexCoordPointer()? Or is this undefined?
      Side note: I'm trying to get an OpenSceneGraph 3.4.0 particle system to use custom vertex, geometry and fragment shaders for rendering the particles.
    • By markshaw001
      Hi i am new to this forum  i wanted to ask for help from all of you i want to generate real time terrain using a 32 bit heightmap i am good at c++ and have started learning Opengl as i am very interested in making landscapes in opengl i have looked around the internet for help about this topic but i am not getting the hang of the concepts and what they are doing can some here suggests me some good resources for making terrain engine please for example like tutorials,books etc so that i can understand the whole concept of terrain generation.
    • By KarimIO
      Hey guys. I'm trying to get my application to work on my Nvidia GTX 970 desktop. It currently works on my Intel HD 3000 laptop, but on the desktop, every bind textures specifically from framebuffers, I get half a second of lag. This is done 4 times as I have three RGBA textures and one depth 32F buffer. I tried to use debugging software for the first time - RenderDoc only shows SwapBuffers() and no OGL calls, while Nvidia Nsight crashes upon execution, so neither are helpful. Without binding it runs regularly. This does not happen with non-framebuffer binds.
      GLFramebuffer::GLFramebuffer(FramebufferCreateInfo createInfo) { glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); textures = new GLuint[createInfo.numColorTargets]; glGenTextures(createInfo.numColorTargets, textures); GLenum *DrawBuffers = new GLenum[createInfo.numColorTargets]; for (uint32_t i = 0; i < createInfo.numColorTargets; i++) { glBindTexture(GL_TEXTURE_2D, textures[i]); GLint internalFormat; GLenum format; TranslateFormats(createInfo.colorFormats[i], format, internalFormat); // returns GL_RGBA and GL_RGBA glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, createInfo.width, createInfo.height, 0, format, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); DrawBuffers[i] = GL_COLOR_ATTACHMENT0 + i; glBindTexture(GL_TEXTURE_2D, 0); glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i, textures[i], 0); } if (createInfo.depthFormat != FORMAT_DEPTH_NONE) { GLenum depthFormat; switch (createInfo.depthFormat) { case FORMAT_DEPTH_16: depthFormat = GL_DEPTH_COMPONENT16; break; case FORMAT_DEPTH_24: depthFormat = GL_DEPTH_COMPONENT24; break; case FORMAT_DEPTH_32: depthFormat = GL_DEPTH_COMPONENT32; break; case FORMAT_DEPTH_24_STENCIL_8: depthFormat = GL_DEPTH24_STENCIL8; break; case FORMAT_DEPTH_32_STENCIL_8: depthFormat = GL_DEPTH32F_STENCIL8; break; } glGenTextures(1, &depthrenderbuffer); glBindTexture(GL_TEXTURE_2D, depthrenderbuffer); glTexImage2D(GL_TEXTURE_2D, 0, depthFormat, createInfo.width, createInfo.height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glBindTexture(GL_TEXTURE_2D, 0); glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, depthrenderbuffer, 0); } if (createInfo.numColorTargets > 0) glDrawBuffers(createInfo.numColorTargets, DrawBuffers); else glDrawBuffer(GL_NONE); if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) std::cout << "Framebuffer Incomplete\n"; glBindFramebuffer(GL_FRAMEBUFFER, 0); width = createInfo.width; height = createInfo.height; } // ... // FBO Creation FramebufferCreateInfo gbufferCI; gbufferCI.colorFormats =; gbufferCI.depthFormat = FORMAT_DEPTH_32; gbufferCI.numColorTargets = gbufferCFs.size(); gbufferCI.width = engine.settings.resolutionX; gbufferCI.height = engine.settings.resolutionY; gbufferCI.renderPass = nullptr; gbuffer = graphicsWrapper->CreateFramebuffer(gbufferCI); // Bind glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo); // Draw here... // Bind to textures glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, textures[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, textures[1]); glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, textures[2]); glActiveTexture(GL_TEXTURE3); glBindTexture(GL_TEXTURE_2D, depthrenderbuffer); Here is an extract of my code. I can't think of anything else to include. I've really been butting my head into a wall trying to think of a reason but I can think of none and all my research yields nothing. Thanks in advance!
    • By Adrianensis
      Hi everyone, I've shared my 2D Game Engine source code. It's the result of 4 years working on it (and I still continue improving features ) and I want to share with the community. You can see some videos on youtube and some demo gifs on my twitter account.
      This Engine has been developed as End-of-Degree Project and it is coded in Javascript, WebGL and GLSL. The engine is written from scratch.
      This is not a professional engine but it's for learning purposes, so anyone can review the code an learn basis about graphics, physics or game engine architecture. Source code on this GitHub repository.
      I'm available for a good conversation about Game Engine / Graphics Programming
  • Popular Now