As suggested I'ved added MAG_FILTER at the top which didn't help. The texture is indeed 64x64; There is this ugly nasty code I have to work with that already has texture mapping working with mipmaps (so I have no idea what the state variables are) but in the code below I am trying to use a nonmipmap texture in place of glDrawPixels without success. The pixel pointer is good as a call to glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels) in the old drawimage works. No gl errors occur. Instead of getting texture mapping I get a rectangle of the color of the last glColor3f which isn't suppose to happen because of glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE) right? So I figure that for some reason texture mapping is being turned off because of some important state variables are wrong. So if you really know opengl well, maybe you can tell me exactly which state variables could possibly cause texture mapping to be turned off here.

void drawDamnTestImage(int width, int height, void *pixels)
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
	static int init = 0;
	static unsigned int i = 0;
	glPushMatrix();
	glLoadIdentity();
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0, 1.0, 1.5, 100);
	if (init == 0) {
		init = 1;
		glGenTextures(1, &i);
		glBindTexture(GL_TEXTURE_2D, i);
		glTexImage2D(GL_TEXTURE_2D, 0, 3,
			width, height, 0, GL_RGB,
			GL_UNSIGNED_BYTE, pixels);
	}
	glBindTexture(GL_TEXTURE_2D, i);
	glMatrixMode(GL_MODELVIEW);
	glTranslatef(0,0,-10);
	glEnable(GL_TEXTURE_2D);
	glBegin(GL_QUADS);
		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  0);
		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  0);
		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  0);
		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  0);
	glEnd();

	glDisable(GL_TEXTURE_2D);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	glMatrixMode(GL_MODELVIEW);
	glPopMatrix();
	if (glGetError() != GL_NO_ERROR)
		exit(0);

[edited by - chare on January 12, 2004 3:33:37 AM] [edited by - chare on January 12, 2004 3:35:36 AM] [edited by - chare on January 12, 2004 1:36:24 PM]

quote:Original post by iNsAn1tY
I notice you specified a minification filter (GL_TEXTURE_MIN_FILTER), but not a magnification filter (GL_TEXTURE_MAG_FILTER). It''s essential that you specify both, or texturing won''t work. The first time I did texturing, I missed out the magnification filter due to a typo, and the texture didn''t show up until I fixed it.

GL_LINEAR is the default magnification filter, so you don''t have to set it explicitly. I bet that there was something else wrong too, and you ''accidently'' fixed both things at the same time, or something like that.

quote:Original post by chare
There is this ugly nasty code I have to work with that already has texture mapping working with mipmaps (so I have no idea what the state variables are) but in the code below I am trying to use a nonmipmap texture in place of glDrawPixels without success. The pixel pointer is good as a call to glDrawPixels(width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels) in the old drawimage works. No gl errors occur. Instead of getting texture mapping I get a rectangle of the color of the last glColor3f which isn''t suppose to happen because of glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE) right?

An invalid texture disables the texture unit, which is likely happening, since you enable texturing, but only the primary color is there. Most common problem is non-power of two dimensions. And you say that it works with mipmaps. Do you mean you use gluBuild2DMipmaps? That function will rescale the image to proper size before uploading it to OpenGL.

Are you sure you are setting the filters for the correct texture object? You are trying to change them at the top there, but you haven''t bound the texture yet. So you may be changing the filter for another texture object. You have to bind the texture before setting its filter properties.

The reason that I think that''s the problem is that, if you have mipmapping elsewhere in the app, and the texture filter for this texture happens to be left as a mipmap filter when you didn''t load in mipmaps, OpenGL disables texturing without telling you. In case that didn''t make sense, check out the filtering section of the Red book. It has a caution about this. If you just load a simple texture (no mipmaps built) and try to turn on a mipmap filter like GL_LINEAR_MIPMAP_LINEAR, OpenGL will disable texturing.

You need to bind the texture object BEFORE you change any texturing parameters.

Thanks that did the trick.