CODEWITHSUNDEEP
c++openglsdl
dj8000
dj8000

Reputation: 209

OpenGL - Texture coordinates on quad

I have no idea what's wrong. Everything seems to be fine. Here's code (texture is loaded, just drawing) :

glBegin( GL_QUADS );
    float TX1,TX2,TY1,TY2;

    TX1=some_numbers_check_below_code;
    TX2=some_numbers_check_below_code;
    TY1=some_numbers_check_below_code;
    TY2=some_numbers_check_below_code;

    glTexCoord2f(TX1,TY2);
    glVertex3f( float(RectOutput.x), float(RectOutput.y), 0.0f );

    glTexCoord2f(TX2,TY2);
    glVertex3f( float(RectOutput.x+InputWidth), float(RectOutput.y), 0.0f );

    glTexCoord2i(TX2,TY1);
    glVertex3f( float(RectOutput.x+InputWidth), float(RectOutput.y+InputHeight), 0.0f );(InputY)/float(Input.H)) );

    glTexCoord2f(TX1,TY1);
    glVertex3f( float(RectOutput.x), float(RectOutput.y+InputHeight), 0.0f );

glEnd();

It's okay with :

TX1=0.0;
TX2=1.0;
TY1=1.0;
TY2=0.0;

(Good : https://i.sstatic.net/2Bj8i.png)

But gets broken with (eg.) :

TX1=0.0;
TX2=0.5;
TY1=1.0;
TY2=0.5;

(Like this : https://i.sstatic.net/Xem99.png)

Really, it annoys me. Probably problem isn't in this code. Everything should be fine ... but it's not.

Any ideas?

Upvotes: 0

Views: 3777

Answers (2)

dj8000
dj8000

Reputation: 209

Oh ... I feel stupid. Sorry for taking time. Here's error :

glTexCoord2i(TX2,TY1);

I should use glTexCoord2 f not i ... Just forgot to change it ...

Upvotes: 2

Zdeslav Vojkovic
Zdeslav Vojkovic

Reputation: 14581

"I have no idea what's wrong. Everything seems to be fine". Great then, no need to answer!

You should first explain what do you expect to get in second case. I am not an OpenGL expert, but your second set of coordinates seem broken.

The first one: 0,0 -> 1,0 -> 1,1 -> 0,1:

  0     1
0 x---->x
  |     |
  |     |
  |     v
1 x<----x

The second one: 0,.5 -> .5,.5 -> .5,1 -> 0,1:

  0     1
0 +-----+
  |     |
  x->x  |
  |  v  |
1 +--x->x

If you want to scale the texture (but I don't know as you haven't written what is supposed to be the result) then this is obviously wrong.

Upvotes: 3

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