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Tiling

Started by krazywest Mar 16, 2003 at 12:14 PM 5 replies 500+ views

Original Post

Mar 16, 2003 at 12:14 PM

I am writing a tile based map engine. The tiles are renderd using this code: glTexCoord2f(0,0); glVertex2f(x*size,y*size); glTexCoord2f(1,0); glVertex2f(x*size+size,y*size); glTexCoord2f(1,1); glVertex2f(x*size+size,y*size+size); glTexCoord2f(0,1); glVertex2f(x*size,y*size+size); At the edge of each tile there appears a line of semi-random pixels. They use colors from else-where in the image and appear blended-like. They are draw using default vc6 GL options -depth testing +cull back face (definetly no blending!). If you want to see it for yourself you can no-longer download Airstrike2. Sorry! [edited by - krazywest on March 19, 2003 2:01:11 PM]

krazywest

Mar 16, 2003 at 2:08 PM

"Through further testing" i''ve worked out that gl is trying to do seamless tiling (Like gimp and psp will do), possibly because the tiles are beeing stretched, but I haven''t turned it on anywhere..

How the crap do you turn this off???
I have a GeForce4 Ti 4400, but I can''t find a setting that makes it happen.

Also, has anyone else had this or any problem with airstrike2?

HellRiZZer

Mar 16, 2003 at 3:16 PM

Maybe you post some code on your problem? There''s, however, a suggestion: don''t draw tile positions as floats (e.g if you draw in XY plane, don''t use x = 5.65 and y = 7.55) but use whole numbers - there might be a rounding off problem.

Good luck.

" Do we need us? "

Ionware Productions - Games and Game Tools Development

cbenoi1

Mar 16, 2003 at 3:39 PM

The texture lookup function is looking slightly off the bitmap when exactly at 1.0. The range should be [0,1[.

You can specify this using the 'border' parameter of ::glTexImage2D(), or by setting the texture coordinate at 0.999999. Also, check how you have specified your texture buffer; it may have been 1 pixel shorter than you tell the ::glTexImage2D() et al. function. Also, if you don't have a power-of-2 picture, make sure you specify the correct ::glPixelStorei( GL_UNPACK_ALIGNMENT, XXX ) value that corresponds with the picture width.

-cb

[edited by - cbenoi1 on March 16, 2003 6:50:11 PM]

Thrump

Mar 16, 2003 at 3:49 PM

Also, depending on what type of texture-filter you use, it may be blending any given pixel with the surrounding pixels. For example, using GL_LINEAR, I had to blit from around 1-1.5 pixels in on all borders. Try turning filtering to NEAREST if it''s already not.

MoonJihad

Mar 16, 2003 at 6:57 PM

Did you set the texture wrap parameters for S and T coordinates to CLAMP_TO_EDGE?

IIRC :
glTexParameteri(GL_TEXTURE_2D, GL_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_WRAP_T, GL_CLAMP_TO_EDGE);

krazywest

Mar 17, 2003 at 2:21 PM

Ok, I had Linear on.

Mipmapping wasn't what I thought it was (meee stuuuuuuuuupid...).

So, is there a way to do linear without rapping it around?
I tried the:

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

idea but it messed up the way I do my transparencies (ie. lots of polygons). Is this because I am stupid or because i'm doing it wrong (the clamping, not the transparanceyyiyngyening)?

[edited by - krazywest on March 17, 2003 3:54:07 PM]

And the answer is... the out of date part of my stupid code that stops the clamp working properly!

[edited by - krazywest on March 18, 2003 2:13:04 PM]

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