My friend and I are debugging our code on different computers.
My code is working while his is not. By process of elimination I determined the problem was that his system was not drawing to the custom frame buffer I use to render to a texture. The texture remained black.
Everything else is the same except for the system. Any advice here?
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
throw new RuntimeException("yo frame buffer is broken);
this does not throw any exceptions so the frame buffer should be made correctly.
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
I added these two lines for my color attachment texture and it worked.
Why does it work now? not completely sure why. GL was saying the FBO was complete even without having this
Related
This is the only part of the code that could be buggy:
GLuint tex_name;
glGenTextures(1, &tex_name);
// set id to the gl_texture_id map for later use
gl_texture_id[t] = tex_name;
// bind texture
glBindTexture(GL_TEXTURE_2D, tex_name);
// set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glGenerateMipmap(GL_TEXTURE_2D);
// load texture data
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA8,t->width(),t->height(),0,GL_BGRA,GL_UNSIGNED_BYTE,t->data());
Could you see something wrong in this code?
enabling glEnable(GL_TEXTURE_2D) is not making the difference. Texture coordinates are right, fragment and vertex shader are right for sure.
SOLVED
That was not the issue, i'm still using glGenerateMipmap (...) before glTexImage2D (...). The real problem is that i passed as format GL_RGBA when my image is in GL_RGB format. Additionally my t->data() array was height*width*sizeof(GL_FLOAT) long and i was passing GL_UNSIGNED_BYTE as type parameter causing data loss. Althougth this works you still have right, in fact preceding glTexImage2D with glGenerateMipmap causes weird effects on Nvidia hardware while life is beautiful (strangely) on ATI GPUs.
Why are you calling glGenerateMipmap (...) on a texture that has no data store?
You need to allocate at least image level 0 before this will work (e.g. call glTexImage2D (...). You should be calling this function after you draw into your texture each frame, the way you have it right now it actually does nothing and when you finally draw into your texture you are only generating an image for 1 LOD. I would remove the mipmap texture filter if you are not going to re-compute the mipmaps everytime you give texture image level 0 data.
I also do not see what this has to do with rendering to a texture? You are passing image data to your texture from client memory. Usually when you render to a texture, this is done using either a pixel buffer (old school) or frame buffer object.
inside my program I'm using glFramebufferTexture2D to set the target. But if I use it the output starts to flicker. If I use two frame buffers the output looks quite normal.
Has anybody an idea why that happens or what can be better inside the following source code? - that is an example and some not relevant code isn't inside.
// bind framebuffer for post process
::glBindFramebuffer(GL_DRAW_FRAMEBUFFER, m_SwapBuffer);
::glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_SwapBufferTargets[SwapBufferTarget1]->m_NativeTextureHandle, 0);
unsigned int DrawAttachments = { GL_COLOR_ATTACHMENT0 };
::glDrawBuffers(1, &DrawAttachments);
...
// render gaussian blur
m_Shader->Use();
::glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_BlurredImageFromPass1->m_NativeTextureHandle, 0);
_InputTexturePtr->ActivateTexture(GL_TEXTURE0);
RenderMesh();
::glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _TargetTexturePtr->m_NativeTextureHandle, 0);
m_BlurredImageFromPass1->ActivateTexture(GL_TEXTURE0);
RenderMesh();
...
// copy swap buffer to system buffer
::glBindFramebuffer(GL_READ_FRAMEBUFFER, m_SwapBuffer);
::glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
::glBlitFramebuffer(0, 0, m_pConfig->m_Width, m_pConfig->m_Height, 0, 0, m_pConfig->m_Width, m_pConfig->m_Height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
EDIT: I found the problem! It was inside my swap chain. I've rendered the original picture and after that a black one. So I get a flicker if frame rate drops.
This is probably better suited for a comment but is too large, so I will put it here. Your OpenGL semantics seem to be a little off in the following code segment:
::glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_BlurredImageFromPass1->m_NativeTextureHandle, 0);
_InputTexturePtr->ActivateTexture(GL_TEXTURE0);
RenderMesh();
::glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _TargetTexturePtr->m_NativeTextureHandle, 0);
m_BlurredImageFromPass1->ActivateTexture(GL_TEXTURE0);
RenderMesh();
glActiveTexture (and thus your ActivateTexture wrapper) is purely for setting the active texture slot when binding a texture INPUT to a sampler in a shader program, and glFramebufferTexture2D is used in combination with glDrawBuffers to set the target OUTPUTS of your shader program. Thus, glActiveTexture and glFramebufferTexture2D should probably not be used on the same texture during the same draw operation. (Although I don't think this is what is causing your flicker) Additionally, I don't see where you bind/release your texture handles. It is generally good OpenGL practice to only bind objects when they are needed and release them immediately after. As OpenGL is a state machine, forgetting to release objects can really come and bite you in the ass on large projects.
Furthermore, when you bind a texture to a texture slot using glActiveTexture (or any glActiveTexture wrapper) always call glActiveTexture BEFORE you bind the texture handle.
I'm having a problem with loading a tga from a PVR.
I believe the PVR is loading correctly, but when I try and load the texture into OpenGL I'm getting issues.
I'm getting odd, incoherant drawings. I'll passing the entire texture file I'm making over to my graphics window class and then asking it to get the id which is an unsigned int and then create the texture.
This is my load texture class.
glGenTextures(animalTexture->getID(), &texture[0]);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glTexImage2D(GL_TEXTURE_2D, 0, 3, animalTexture->getWidth(),animalTexture->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, animalTexture->getImageData());
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
I'm wondering what the cause could be. This method does get called more than once so I'm wondering if you can overwrite a previously generated texture without any issues? Do you have to have a gluint to use to generate a texture? I'm trying to load a tga.
I know this draws successfully with a normal saved image.
Any ideas or help would be mucn appreciated.
p.s Ignore the black spot that was me.
Have a look at this post. Essentially, as PVR is compressed, you can't send the texture using glTexImage2D which assumes uncompressed texels (each texel being 4 unsigned bytes in the code you posted). You must use glCompressedTexImage2D instead which handles compressed formats. Have a look at this OpenGL es extension to know which internal format to use. If you're not too sure which one to choose or just want to view your compressed textures, PVRTexTool looks like a nice tool.
I'm loading raw texture (with alpha channel) and displaying it in openGL everything is fine and texture displayed, but color is little bit darker than original. I already tried to turn of lighting, blending and dithering, but this doesn't helps.
I'm using mac osx.
Sample image
http://postimage.org/image/2wi1x5jic/
Here's openGL texture loading source code:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA , width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, &bytes[0]);
EDIT:
Thats very weird, I used example from http://forums.tigsource.com/index.php?topic=9560.0
and received same glitch ... So the problem not im my code, maybe driver options? Hm ...
SOLUTION:
Thanks #datenwolf, images were saved with sRrgb color profile. Problem is solved once I removed it and converted to RGB.
Maybe you have GL_MODULATE set as texturing environment and the vertex colours are not white. Try setting the texture environment to GL_REPLACE.
glBindTexture(GL_TEXTURE_2D, your_texture);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
EDIT
Another problem may be a color profile embedded into the image. A image viewer may use this colour profile to implement color management, adjusting the colours for your monitor's colour profile. OpenGL as-it-is doesn't do color management; there is a extension, that framebuffers and textures are sRGB, this is kind of the smallest common denominator of colour management. But then you'd still have to transfer your input images to sRGB colour space.
I've a lengthy article in preparation the explains in depth how to do colour management with OpenGL. But it's far from complete.
After making a few changes in my application, my textures are no longer showing. So far I've checked the following:
The camera direction hasn't changed.
I can see the vectors (when colored instead of textured).
Any usual suspects?
You may want to check the following:
glEnable(GL_TEXTURE_2D); presence
glBindTexture(GL_TEXTURE_2D,
texture[i]); and
glBindTexture(GL_TEXTURE_2D, 0);
when you don't need texture anymore
One common problem I run into from time to time is
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
but I forgot to supply mipmaps. Quickfix:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
A few more things to check:
glColorMaterial(...); To make sure colors aren't overwriting the texture
glEnable/glDisable(GL_LIGHTING); Sometimes lighting can wash out the texture
glDisable(GL_BLEND); Make sure that you're not blending the texture out
Make sure the texture coordinates are set properly.
I assume you had the must have operations implemented like glEnable(GL_TEXTURE_2D) and the texture binding since your textures worked fine before and then suddenly they just won't show.
If you are doing Object Oriented code you might want to have the texture generation happen when the thread that is actually doing the draw is instanced, in other words: avoid doing it in constructors or a call coming from a constructor, this might instance your texture object before the window or the app that is going to use it is on.
What I usually do is that I create a manual Init function of the texture creation that is called in the Init function of the App. Therefore I guarantee that the App exist when the binding occurs.
More info here: http://www.opengl.org/wiki/Common_Mistakes#The_Object_Oriented_Language_Problem
Does a glColor3ub(255,255,255) before rendering your textured object help? I think the default OpenGL state multiplies the current glColor by the incoming texel; a stray glColor3ub(0,0,0) will make all your textures look black.
Took me some while to figure this out...
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glDisable(GL_TEXTURE_GEN_S);
glDisable(GL_TEXTURE_GEN_T);
glDisable(GL_TEXTURE_GEN_R);
glDisable(GL_TEXTURE_GEN_Q);
Also make sure to unbind your stuff:
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glBindVertexArray(0);
If you use a third party engine, which is optimized, it probably has a "direct state access" layer for OpenGL (to not use the slow OpenGL query functions). If so, don't call OpenGL directly, but use the engine wrappers. Otherwise your code doesn't play nice with the rest of the engine code.