From: Benedikt Kessler (bjk++at++munich.sgi.com)
Date: 10/04/2001 00:37:14
Hi!
I assume that you're running in sigle process mode; If not you will have
crashes calling OpenGL calls in the APP or CULL processes as they do bat
have a graphics context. So calling glGenTextures (or any other gl*
call) will only be allowed in the DRAW process.
By calling glGenTextures(1, texture) only the first element (index 0!!!)
of the texture array is initialized; that means that you must call:
glBindTexture(GL_TEXTURE_2D, texture[0]);
^^^ instead of 1!!!
So both the sample code and your own code were wrong...
You might also either call glTexParameteri(GL_TEXTURE_2D,
GL_TEXTURE_MIN_FILTER, GL_LINEAR); or define all mipmap levels in your
code! For the default GL_NEAREST_MIPMAP_LINEAR minification filter all
mipmap levels must be defined (or no texturing is used).
Bye! Benedikt
> Hi..
>
> I am student of Sogang Univ. in Seoul, Korea, and my name is Im, Moo
> Jin...
>
> I saw the following reply at Info-Performer Mailing List (2000.10)
>
> ------------------------------------------------------------------------------------
>
> Hi,
>
> did you use glGenTextures to generate the texture name? I did the same
>
> thing and it worked out well. Here is what I did (the main idea):
>
> Init time:
> glGenTextures(1, texture)
>
> Post Draw time:
> // copy frame buffer to texture
> glBindTextureEXT(GL_TEXTURE_2D,texture[1]);
> glCopyTexSubImage2DEXT(GL_TEXTURE_2D, 0, 0, 0, 0, 0, sizeX, sizeY);
>
> // draw textured quad with frame buffer texture
> pfPushIdentMatrix();
> pfEnable(PFEN_TEXTURE);
> glEnable(GL_TEXTURE_2D);
> glBindTextureEXT(GL_TEXTURE_2D,texture[1]);
> glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE);
> glBegin(GL_QUADS);
> glColor4f(1.0f,1.0f,1.0f,1.0f);
> glTexCoord2f(0.0f,0.0f); glVertex2f(-1.0f,-1.0f);
> glTexCoord2f(1.0f,0.0f); glVertex2f(1.007f,-1.0f);
> glTexCoord2f(1.0f,1.0f); glVertex2f(1.007f,1.005f);
> glTexCoord2f(0.0f,1.0f); glVertex2f(-1.0f,1.005f);
> glEnd();
>
> regards, Sylvain
>
> ------------------------------------------------------------------------------------
>
> So. I programming refer to this code.
>
> I want programming simple 2d texture code using OpenGL.
>
> My code is :
>
> ------------------------------------------------------------------------------------
>
> In Main Function :
>
> /* This is from Opengl Programming Guide */
> glGenTextures(1, texture);
> for(i=0; i<checkImageHeight; i++) {
>
> for(j=0; j<checkImageWidth; j++) {
> c = ((((i&0x8)==0)^((j&0x8))==0))*255;
> checkImage[i][j][0] = (GLubyte) c;
> checkImage[i][j][1] = (GLubyte) c;
> checkImage[i][j][2] = (GLubyte) c;
> checkImage[i][j][3] = (GLubyte) 255;
> }
> }
> glBindTextureEXT(GL_TEXTURE_2D, texture[1]);
> glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,
> checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE,
> checkImage);
>
> In channelSetup Function :
>
> pfChanTravFunc(chan, PFTRAV_DRAW, drawHUD);
>
> In drawHUD Function :
>
> {
>
> pfClearChan(chan);
> pfDraw();
>
> /* post draw */
> pfPushIdentMatrix();
> pfEnable(PFEN_TEXTURE);
> glEnable(GL_TEXTURE_2D);
no need to glEnable(GL_TEXTURE_2D); if pfEnable(PFEN_TEXTURE); is
already used.
> glBindTextureEXT(GL_TEXTURE_2D, texture[1]);
> glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
>
> glBegin(GL_QUADS);
> glColor4f(1.0, 1.0, 1.0, 1.0);
> glTexCoord2f(0.0, 0.0); glVertex2f(-1.0f,-1.0f);
> glTexCoord2f(1.0, 0.0); glVertex2f( 1.0f,-1.0f);
> glTexCoord2f(1.0, 1.0); glVertex2f( 1.0f, 1.0f);
> glTexCoord2f(0.0, 1.0); glVertex2f(-1.0f, 1.0f);
> glEnd();
> }
>
> ------------------------------------------------------------------------------------
>
> Please check my code..
>
> What is the problem...?
>
> Because this problem, I can't proceed my job.
>
> Please answer my question.
>
> Besides if possible, send me sample texture program code using Opengl.
>
>
>
> Im, Moo Jin
>
> p.s. Sorry, My terrible English..:-)
-- +---------------------------------+----------------------------------+ |Benedikt J. Kessler | Silicon Graphics GmbH | |Professional Services | Am Hochacker 3 - Technopark | |SGI | 85630 Grasbrunn-Neukeferloh, FRG | | --- __o ,__o | | | ------_ \<,_ _-\_<, | Phone: (+49) 89 46108-366 or -0 | |----- (*)/ (*) (*)/'(*) | Fax: (+49) 89 46107-366 | +---------------------------------+----------------------------------+ |E-Mail: bjk++at++sgi.com Web (private): http://reality.sgi.com/bjk | | Web: http://www.sgi.de/dienstleistungen/ | +--------------------------------------------------------------------+
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