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glGenTextures() memory problem.

Started by yahn Aug 10, 2007 at 9:30 PM 2 replies 2.2k views

Original Post

Aug 10, 2007 at 9:30 PM

I have a while loop that is in a display list that is something like this:


while (i < l)
{
  glGenTextures(1, &tex);
  ...
  glDeleteTextures(1, &tex);
}

I thought that when glDeleteTextures() is called it deletes all the memory glGenTextures() allocates. Why Am I getting memory leaks when I run this while loop? And the code in between isn't causing the problem because when I comment out the gl functions there is no leak. However, I need to generate a texture so I can't just leave them commented out.

Stani R

Aug 10, 2007 at 9:37 PM

I'm not completely sure if this will help you fix your problem, but there's a related thread from 2003 which describes the same phenomenon and proposes a solution.

zix99

Aug 10, 2007 at 9:38 PM

What exactly is the leak from? glGenTextures() just creates a texture ID (no memory to my knowledge is even located.. it simply returns a unique, unused, number) (In my programs i don't even use glGenTextures, i simply create a unique ID).

You claim it's not your code creating the memory leak, but, it'd be a good idea to show us the code anyway. Also, how do you know it's creating a memory leak? (Does it pop up an exception? Or are you using some memory manager (ie mmgr) ).

~Chris

yahn

Aug 10, 2007 at 9:50 PM

I'm looking at the memory for the program and it goes up about 500kbs a second consistently. When comment out those lines it doesn't go up. So, I don't see much need in putting in the code. Especially because it's some sloppily written code that is awfully inefficient. But:

int ft_render_glyph(char c, GLuint texture, int ox, int oy){	FT_UInt glyph_index = FT_Get_Char_Index(ft_face, c);	FT_UInt error = FT_Load_Glyph(ft_face, glyph_index, FT_LOAD_DEFAULT);	if (error)	{		return 0;	}	error = FT_Render_Glyph(ft_face->glyph, FT_RENDER_MODE_NORMAL);	if (error)	{		return 0;	}	int width  = power2(ft_face->glyph->bitmap.width);	int height = power2(ft_face->glyph->bitmap.rows);	GLubyte* expanded_data = new GLubyte[ 2 * width * height];	for (int j = 0; j < height; j++)	{		for (int i = 0; i < width; i++)		{			expanded_data[2*(i+j*width)]= expanded_data[2*(i+j*width)+1] = 				(i>=ft_face->glyph->bitmap.width || j>=ft_face->glyph->bitmap.rows) ?				0 : ft_face->glyph->bitmap.buffer[i + ft_face->glyph->bitmap.width*j];		}	}	glBindTexture(GL_TEXTURE_2D, texture);	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_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, expanded_data);	delete [] expanded_data;	glTranslatef(ft_face->glyph->bitmap_left, 0, 0);	glTranslatef(0, -ft_face->glyph->bitmap_top, 0);	float x = (float)ft_face->glyph->bitmap.width/(float)width;	float y = (float)ft_face->glyph->bitmap.rows/(float)height;	render_texture(texture, ox + ft_face->glyph->bitmap_left, oy + y + 16, width, height);	return ft_face->glyph->advance.x >> 6;}glGenTextures(1, &tex);o += ft_render_glyph(str, tex, o + x, y);glDeleteTextures(1, &tex);

The glGenTextures causing the memory to go up is confusing me as much as you. Does anyone have an idea?

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