I've been having a very weird issue with my project's texture generation. The first mipmapped texture works flawlessly but the next ones only draw the first level. While debugging I suddenly came to a hack that fixes it:
glGenTextures(1, &texture->textureID);
glBindTexture(GL_TEXTURE_2D, texture->textureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexStorage2D(GL_TEXTURE_2D, 10, GL_RGBA8, width, height);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
glGenerateMipmap(GL_TEXTURE_2D);
assert(glGetError() == GL_NO_ERROR); // Mipmapping fails if glGetError is not here
glBindTexture(GL_TEXTURE_2D, 0);
Why on earth is this only working when a glGetError (which, as you can see with this assert, is ALWAYS returning GL_NO_ERROR) function is called after the glGenerateMimap? Why does it have anything to do with it?
I'm currently using a GeForce GTX 670 with the latest GeForce 340.52 driver
Edit: A couple of images might help
With glGetError():
Without glGetError():
Referring to Is iOS glGenerateMipmap synchronous, or is it possibly asynchronous?, it seems glGenerateMipmaps works asynchronously. My project uses shared contexts to create shaders, textures and meshes (sorry if I didn't mention this, I didn't think it would matter).
The thing is, whenever the texture generation finished the "textures generated" flag was risen and the shared context would get destroyed, it seems the last glGenerateMipmap was therefore not getting flushed through the pipeline. The call to glGetError needs to flush the operations from the pipeline to see whether there's been any error to report, and this is exactly why it was making everything work flawlessly.
So, in other words, if you're doing something on a separate, shared context, you need to explicitly call glFinish before killing that thread, or some operations will be left undone.
Related
I am rendering a huge 3D cube array, that sometimes counts thousands of cubes aligned right next to one another. I am rendering a jpg texture to the cubes, which is just a simple color with a black border around the frame.
The problem:
The array is huge, and the distant parts of the array get kind of mixed into one another, so to say. In other words, the borders in the distant cubes sometimes completely disappear, sometimes they form an arbitrary wavey line together with other neighboring borders. All in all, the scene looks kind of messy because all the fine details (hard borders between the neighboring cubes) are lost/melted together. After searching for the solution online, I understand that the problem might be in my choice of texture filtering options.
This is how the problem actually looks like in OpenGL:
This is how the current code for loading texture and setting texture parameters looks like:
glGenTextures(1, &texture3);
glBindTexture(GL_TEXTURE_2D, texture3);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
// set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//load image:
data = stbi_load("resources/textures/gray_border.jpg", &width, &height, &nrChannels, 0);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
By now, I have tried playing with changing different parameters to the function glGenerateMipmap() and altering between the parameters in the glTexParameteri() function, but none did work by now.
If you want to enable Mip Mapping, then you have to use one of the minifying functions like GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR or GL_LINEAR_MIPMAP_LINEAR, see glTexParameter and Texture - Mip Maps:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
A further improvement can be gained by Anisotropic filtering, which is provides by the extension ARB_texture_filter_anisotropic and is a core feature since OpenGL 4.6.
e.g.
glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY, 16);
See Sampler Object - Anisotropic filtering
In my application I am using extensively glTexImage2D. I copy some image of an image and render it as a texture, I do it frequently at every mouse click. I give it as a byte array for rendering. The memory is being eaten up and the swap memory is also allocated. Is it a memory leak? or is it due to the fact that glTexImage2D holds any references or anything else.
Edit:
//I allocate the memory once
GLuint texName;
texture_data = new GLubyte[width*height];
// Each time user click I repeat the following code (this code in in callback)
// Before this code the texture_data is modified to reflect the changes
glGenTextures(3, &texname);
glBindTexture(GL_TEXTURE_2D, texname);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE,texture_data);
I hope your close requests and down voting would stop now!
Assuming you're generating a new texture with glGenTextures every time you call glTexImage2D, you are wasting memory, and leaking it if you don't keep track of all the textures you generate. glTexImage2D takes the input data and stores it video card memory. The texture name that you bind before calling glTexImage2D - the one you generate with glGenTextures is a handle to that chunk of video card memory.
If your texture is large and you're allocating new memory to store more and more copies of it every time you use it, then you will quickly run out of memory. The solution is to call glTexImage2D once during your application's initialization and only call glBindTexture when you want to use it. If you want to change the texture itself when you click, only call glBindTexture and glTexImage2D. If your new image is the same size as the previous image, you can call glTexSubImage2D to tell OpenGL to overwrite the old image data instead of deleting it and uploading the new one.
UPDATE
In response to your new code, I'm updating my answer with a more specific answer. You're dealing with OpenGL textures in the wrong way entirely The output of glGenTextures is a GLuint[] and not a String or char[]. For every texture you generate with glGenTextures, OpenGL gives you back a handle (as an unsigned integer) to a texture. This handle stores the state you give it with glTexParameteri as well a chunk of memory on the graphics card if you give it data with glTexImage[1/2/3]D. It's up to you to store the handle and send it new data when you want to update it. If you overwrite the handle or forget about it, the data still stays on the graphics card but you can't access it. You're also telling OpenGL to generate 3 textures when you only need 1.
Seeing as texture_data is of a fixed size, you can update the texture with glTexSubImage2D instead of glTexImage2D. Here is your code modified to avoid the memory leak from this issue:
texture_data = new GLubyte[width*height]();
GLuint texname; //handle to a texture
glGenTextures(1, &texname); //Gen a new texture and store the handle in texname
//These settings stick with the texture that's bound. You only need to set them
//once.
glBindTexture(GL_TEXTURE_2D, texname);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
//allocate memory on the graphics card for the texture. It's fine if
//texture_data doesn't have any data in it, the texture will just appear black
//until you update it.
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB,
GL_UNSIGNED_BYTE, texture_data);
...
//bind the texture again when you want to update it.
glBindTexture(GL_TEXTURE_2D, texname);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, 0, GL_RGB,
GL_UNSIGNED_BYTE, texture_data);
...
//When you're done using the texture, delete it. This will set texname to 0 and
//delete all of the graphics card memory associated with the texture. If you
//don't call this method, the texture will stay in graphics card memory until you
//close the application.
glDeleteTextures(1, &texname);
I'm getting segfaults and can't figure out why. The person I'm working with compiles and runs correctly on an OSX machine. gdb backtrace gives me that it's coming from this section of code, specifically, from glGenFramebuffers:
// Render the warped texture mapped triangles to framebuffer
GLuint myFBO;
GLuint myTexture;
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &myTexture);
glBindTexture(GL_TEXTURE_2D, myTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, size.width, size.height, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glGenFramebuffers(1, &myFBO);
glBindFramebuffer(GL_FRAMEBUFFER_EXT, myFBO);
I'm running 12.04 Ubuntu with an Nvidia card using the latest proprietary drivers from Nvidia provided by the OS. I'm not incredibly familiar with OpenGL, a lot of this code is my partner's, and he seems to be stumped as well. If you need any further information, I'm happy to provide it.
The answer actually turned out to be really simple. OSX coders don't need to call glewInit() before they start using glew calls - Linux and Windows users do. Also, another bit of interesting information I found out: Check if you're able to perform direct rendering using glxinfo. It can make all the difference when running OpenGL programs.
I'm having some trouble with a render-to-texture operation. I create a FBO, attach a texture, render to it, and everything's fine, but when I try to change the attached texture, either to 0 or to a new handle, by calling glFramebufferTexture2DEXT again, the texture I had attached becomes blank (all pixel values reset to (0, 0, 0, 0)).
The documentation doesn't say that this is supposed to happen, and it's a bit troublesome for me because I need to retain the information in this texture. Does anyone know why this is happening, and how to prevent or work around it?
Just ran into a nearly the same situation. The end solution was when we were creating the texture we had to make sure to set up the TexParameters.
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
According to https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glTexParameter.xhtml, GL_TEXTURE_MIN_FILTER defaults to GL_NEAREST_MIPMAP_LINEAR but we weren't mipmapping. I am not sure why that would cause the texture to appear to be erased, but that is what we did to fix it.
I have got a very, very strange problem in my C++ OpenGL application.
I simply load a texture and apply it to a quadric:
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexImage2D(GL_TEXTURE_2D, 0, 3, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
Then
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, tex);
gluQuadricDrawStyle(quad,GLU_FILL);
gluQuadricTexture(quad,GL_TRUE);
gluCylinder(quad,1,0,2,20,1);
glDisable(GL_TEXTURE_2D);
Now: it works perfectly 9 times out of ten, but sometimes the texture isn't shown (the quadric stays white).
The image is correctly loaded, so the problem should be with OpenGL. I have tried with several different images too. Always GL_NO_ERROR.
Any idea ? It is driving me crazy...
Found :) It was the GLint texture member that wasn't correctly reallocated in the copy constructor.
However, i still don't understand why it worked sometimes...
The code you are using seems valid. Have you ...
tried to use a simple quad instead of the quadric
assured that image is filled correctly
verified that tex is not altered somewhere else
assured that no other programs are using opengl at the same time
restarted your computer ;)