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OpenGL problem?

Started by Hydra13 Feb 27, 2003 at 12:27 AM 13 replies 2.4k views

Original Post

Feb 27, 2003 at 12:27 AM

I am trying to make my triangle move on the X axis and the Y axis but it isnt working... it only moves on the X axis, could someone help me out. Code is: case WM_KEYDOWN: { keys[wParam] = TRUE; if (keys[VK_LEFT]) { glRotatef(rtri,1.0f,0.0f,0.0f); rtri-=3.0f; } else if(keys[VK_RIGHT]) { glRotatef(rtri,1.0f,0.0f,0.0f); rtri+=3.0f; } glRotatef(rtri,0.0f,1.0f,0.0f); glLoadIdentity(); if (keys[VK_UP]) { glRotatef(rtri,0.0f,1.0f,0.0f); rtri+=3.0f; } else if(keys[VK_DOWN]) { glRotatef(rtri,0.0f,1.0f,0.0f); rtri-=3.0f; }

Cat_B

Feb 27, 2003 at 12:54 AM

glRotatef(rtri,0.0f,1.0f,0.0f);
glLoadIdentity();

well, I''m not sure of your program, but why do you do these commands in the middle? Try putting the loadidentity at the top and forgetting the other line. You also say you want to "move on the x axis" If you want to move in a straight line us glTranslate not glRotate. Anyway, just my 2 cents.

Hydra13

Feb 27, 2003 at 12:56 AM

Oh... sorry i wasn''t clear enough.... i want to rotate it on the x axis!

Hydra13

Feb 27, 2003 at 12:59 AM

I hope people are still reading here... but i want the triangle''s y axis to move like when they hit down it rotates downward...when they hit up rotate upwards, but when i hit up or down it still goes to the left or right!?

Cat_B

Feb 27, 2003 at 1:07 AM

You mean rotate "around" the x axis

(the x axis is the line going right-left and you want your triangle to swing around that line) Same advice as above- move loadIdentity to the top and delete the other line.

Hydra13

Feb 27, 2003 at 1:10 AM

I did that but it still doesnt work

Cat_B

Feb 27, 2003 at 1:16 AM

do you have a case WM_KEYUP where you set the key to false?

Hydra13

Feb 27, 2003 at 1:29 AM

This is before that other statement:

case WM_KEYUP:
{
keys[wParam] = FALSE;
return 0;
}

RipTorn

Feb 27, 2003 at 1:31 AM

sorry. I can''t help but think that the code you just posted is unsavable.
the fact you think it''s a bug in GL suggests to me you have A LOT to learn.

I know it''s harsh but it''s true.

consider getting a good C++ book and reading about matrices then move onto GL once you are confident there.

| - Project-X - my mega project.. yup, still cracking along

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neurokaotix

Feb 27, 2003 at 1:51 AM

Gosh, that''s harsh... but true.

RipTorn

Feb 27, 2003 at 4:28 AM

yeah. I know. and I appologize. I''m not really in the mood for sugar coating my replies tonight

| - Project-X - my mega project.. yup, still cracking along

- | - adDeath - an ad blocker I made - | - email me - |

lowlevel

Feb 27, 2003 at 4:40 AM

Do you know what glLoadIdentity() does? It doesn''t seem like it or you wouldn''t put it right after a glRotatef(). Find out what it does.

You seem to have missunderstood rotations, and what rotation around an axis mean.

Imagine a drilling machine. Think of the drill as for example the x-axis. You have just drilled through a cube. If you start your drilling machine and let the cube rotate along with the drill, you have rotation around the x-axis.

Ofcourse this example applies the y-axis and z-axis too.

cowsarenotevil

Feb 27, 2003 at 12:20 PM

You actually can do a surprising amount without understanding matrices..... they''re good to know, but opengl''s functions generally don''t require you to understand them.

-~-The Cow of Darkness-~-

cowsarenotevil

Feb 27, 2003 at 12:20 PM

You actually can do a surprising amount without understanding matrices..... they''re good to know, but opengl''s functions generally don''t require you to understand them.

-~-The Cow of Darkness-~-

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