   Disgusting mistakes...
  Hi everybody (First post over the OGL forum  ) :Maybe this question is almost stupid, i don''t know, it''s probably a problem of concepts ''bout 3D, but at the moment I can''t find the answer.The problem appears when using space 3D management functions, like glTranslatef , for example, but after testing some things i don''t know if the problem is over the coordinates system (Is this possible???).The most disgusting aspect, is to me , that the problem appears even if I use examples , that you can find over webs (NeHe) or books (Programming over OpenGL). for example (Very simple) ->void Render(void){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity();glTranslatef(-1.5f,0.0f,-6.0f);glBegin(GL_TRIANGLES);// Code of triangle hereglEnd();}Here glTranslatef moves the scene 1.5 units left, and 6 into the screen. Well, if I use this, the window appears black. But, if I use glTranslatef(0.0f,0.0f,0.0f) appears correctly. If I try to translate the scene 1 unit into the window appears ok, but if I try -1.1f appears black.It seems like the coordinates used in the NeHe example doesn''t work in my system!!!Thanks for reading,Jacob. 
  if not stated otherwise glTranslatef(x,y,z); affects the current modelview matrix as in rewrites elements 12,13,14 with those supplied by you.The problem is that the projection plane is set "in front" of your triangle , try glTranslate-ing after drawing the triangle. ;  "If I try to translate the scene 1 unit into the window appears ok, but if I try -1.1f appears black."then i would first check the near and far planes you set. ;  How are you drawing your triangle (i.e. what coords are you using) and how have you set up your projection matrix?  ;Yes i''d say its probably the near / far clipping planes. Strange that you even get an image with no translation, unless you''re coordinates have substantial negative z values. ~SPH;  or probably it''s just that he is in Projection-Matrix-Mode, and there coordinates are given INVERSED.glMatrixMode(GL_PROJECTION);glTranslatef(0.0f, 0.0f, -6.0f);will translate towards the viewer.the other posibility is that __they__ uses this: glOrtho(-1, 1, -1, 1, -1, 1);so you can only see things with -1 < x < 1; -1 < y < 1; -1 < z < 1 (homogenous space).if you are in PROJECTION-matrix-mode and you reset it with glLoadIdentity() you should allways rebuild the projection-matrix via glOrtho or glFrustum/gluPerspective. Look into your tutorials for that.to test in which matrixmode you are you can useint i;glGetIntegerv(GL_MATRIX_MODE, &i);if( i == GL_MODELVIEW )  /*you are in modelview mode*/else  /* you are in projection mode */;  Hi, and first I'm sorry, I've had a 'delay', so thanks everybody for posting. Some problems have been solved.I have been trying to set up my concepts, and I've questions ... Let's see a bit of functions ->glViewport(0,0,width,height);This function, sets the "space" where OpenGL can write. The two initial zeros sets where OpenGL starts the view???.gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.0f,100.0f);Ok, this is easier  ... the first are the vision & direction degrees. Then width/height sets the aspect ratio. The last values sets the max planes (near/far). Question , using gluPerspective, if we're over a window of 640x480 (640/480 = 1,33), Is -1.33 to 1.33 the maxium line that we can draw over the X axis?And, the last question. For those who have read till this point my congratulations . Thats a strange effect. If I create a window (800,600 f.e), and set a text that is just in the corner of the window (That's the desired effect), if I resize the window (1024,768 in window) that texts moves a bit down in the window. Why?I hope everybody understands me...and ... thanks for reading, always.Greetings,Jacob.   [edited by - jacob84 on July 30, 2003 5:06:39 PM];gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.0f,100.0f);   ^   | wrongThe near clip plane must be positive. ;  that''s because the viewport needs to be resetuped every time the window changes it''s size. the aspect ratio needs to be positive because it is a relation between the top and the right plane.the distance to the near plane needs to be a nonzero value because you divide through it while z-testing. 