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OpenGL Strange problem with functions not working properly on different unit in project

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So i have a project with lets say two units, one is main unit second is other unit.

I am trying to make glCopyTexSubImage2D to work, when i use exactly same code in main unit it works but it doesnot work in other unit.

code that causes problem is

(i use it in other unit)

  glGenTextures(1, &beforetex);       
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, 2048, 2048, GL_RGBA, GL_UNSIGNED_BYTE, colorbuffer_pdata);


dont even try to tell me that glubuildmipmaps isnt used for ages even glteximage2d does not work so just shut up.





when i call this code from main unit glcopytexsubimage2d works, but when this code is called from different unit texture is not updated and i see only white texutre nothing more.


i already found that i used two different glCopyTexSubImage2D functions, so i corrected that.





here are some addidional details.

other unit contains a Aircraft class which contains Cockpit class which contains HUD class which contains:

   unsigned int *   colorbuffer_pdata;
   unsigned int beforetex;

like i said already or not in other unit i do

colorbuffer_pdata = new unsigned int [2048*2048*4];

then i have to call (in main unit)

glGenTextures(1, &AUTOS->cockpit->HUD->beforetex);        
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, 2048, 2048, GL_RGBA, GL_UNSIGNED_BYTE, AUTOS->cockpit->HUD->colorbuffer_pdata);

then i can use (in other unit)

Mainunit->glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, sw, sh);

and it works...


it obvious that something is with these functions so i wanted to find their addresses to compare but debugger says it can't find addreses of these functions (i dont know becasue they are opengl function it cant find it)


so (in main unit) i decided to make a function that will initialize texture for other unit.

void __fastcall Mainunit::TEXTURE_CREATE(int sw, int sh, unsigned int  tex,unsigned int * pdata)
glGenTextures(1, &tex);         
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, 2048, 2048, GL_RGBA, GL_UNSIGNED_BYTE, pdata);

then in other unit after making this unsigned int array i called


but it wont work (i get same result: white texture and no update)



but before making this function i was using different code (in mainunit)

the difference was that  AUTOS->cockpit->HUD->colorbuffer_pdata this unsigned int * was global declarated in other unit

and when i made

 colorbuffer_pdata = new unsigned int [2048*2048*4]; //in other unit

and tried to initialize texture from mainunit it crashed saying acces violation (glubuildbitmaps hex address) violation 000000 so it was saying that i didint create this array pointer or what? it couldnt find it (so i moved colorbuffer_pdata to HUD class and i could initialize texture w/o problems] 


So here now some question come: why such limitation occured (acces violation)? and how do i get addresses for glTexParameteri, glTexEnvi, glBindTexture,glGenTextures, glEnable, gluBuild2DMipmaps , GL_TEXTURE_2D,GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE  etc. so i could compare it to those from main unit.



OR maybe thers another solution to the problem, 


All i need is to initialize texture inside HUD class, but it seems i cant do that.










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Maybe just calling glDisable(GL_TEXTURE_2D) is a problem. In my opinion, in this case you should check if GL_TEXTURE_2D object is enabled during rendering your textured geometry into framebuffer.

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looks suspicious to me, is that a different context?


Also, you are allocating 2048*2048*4 uints, which is 67mb, instead of the 16.7mb you really wanted.

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First, define “unit”. Translation unit?
Second, welcome to the terrible world of state machines, one of the biggest flaws in OpenGL.
For one, your call to glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); is meaningless there; that is not a state related to textures.  Set it before drawing, not when creating a texture.

For another, as a state machine, things 10 miles away in other parts of your code can affect this part of your code.


Also, contexts?  How many?  Which is active when?

Is the texture enabled?


Use a debugger such as gDEBugger and figure out what states are set and the contents of the texture.



L. Spiro

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