opengl texture filter

[MTR]

Hello!

I'm having a problem with the filtering in textures.
When I scale the image to bigger, the linear filter is not working (looks more nearest than linear).
This is the result I'm having:

(image on the left is ratio 1, so it looks Ok. Image on the right has ration 1.5 and looks too pixeled)

And this is the result I have in PC and Android phones:



Concerning the code of creation of texture, I'm doing the same than everyone else:

glBindTexture (GL_TEXTURE_2D, idx);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexEnvi (GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);

Texture is ARGB 8888.

Any idea of why is this happening?

Thank you in advance!

[Bounty Bob]

You say that it looks more like a nearest filter than linear, but have you set the filters to nearest to see how the results are? Im guessing it will look worse.

Whenever I've needed to display a larger image, I've always used a larger source image for better quality, unless it's only going to be seen at that larger size briefly.

*edit* Are you doing this at the glGenTextures point of the code?

[MTR]

Thanks for your answer,

I check GL_NEAREST and looks the same than GL_LINEAR.

For special effects, I need to change the size of displayed images.
I have the same problem when using a larger source image and displaying it smaller.

The fact is that I haven't see this problem in other games.

This is the whole code when creating textures:

glGenTextures(1, &idx);

glBindTexture (GL_TEXTURE_2D, idx);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexEnvi (GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)w,(GLsizei)h, 0, GL_RGBA, GL_UNSIGNED_BYTE, dataChar);

[warmi]

Originally Posted by MTR

Hello!

I'm having a problem with the filtering in textures.
When I scale the image to bigger, the linear filter is not working (looks more nearest than linear).
This is the result I'm having:

(image on the left is ratio 1, so it looks Ok. Image on the right has ration 1.5 and looks too pixeled)

And this is the result I have in PC and Android phones:



Concerning the code of creation of texture, I'm doing the same than everyone else:

glBindTexture (GL_TEXTURE_2D, idx);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexEnvi (GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);

Texture is ARGB 8888.

Any idea of why is this happening?

Thank you in advance!

Are your textures power of 2 ?

[Bounty Bob]

Originally Posted by MTR

Thanks for your answer,

I check GL_NEAREST and looks the same than GL_LINEAR.

For special effects, I need to change the size of displayed images.
I have the same problem when using a larger source image and displaying it smaller.

The fact is that I haven't see this problem in other games.

This is the whole code when creating textures:

glGenTextures(1, &idx);

glBindTexture (GL_TEXTURE_2D, idx);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexEnvi (GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)w,(GLsizei)h, 0, GL_RGBA, GL_UNSIGNED_BYTE, dataChar);

You have the same as I do for texture generation, except I don't have the glTexEnvi. Are you using this later for your effects? Maybe try taking it out and seeing if scaling is affected.

How are you drawing the objects?

And as above, what are the dimensions of your textures?

[MTR]

Thanks for your answer,

The problem was that I was repeating glTexParameteri when rendering the triangle fan.
Looks like calling glTexParameteri after creating textures disables the LINEAR filter of all textures.

Solution:

uploadTexture ()
{
glGenTextures(1, &idx);

glBindTexture (GL_TEXTURE_2D, idx);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexEnvi (GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)w,(GLsizei)h, 0, GL_RGBA, GL_UNSIGNED_BYTE, dataChar);
}

rendering()
{
[...]
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
//	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
[...]
}