int draw_scene ( GLvoid )
// draws the scene
{
// clear the screen and the depth buffer
glClear ( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
// reset the matrix
glLoadIdentity ( );
glPushMatrix ( );
// move to the cube's position
glTranslatef ( unit[0].x, unit[0].y, unit[0].z );
// select the cubes texture
glBindTexture ( GL_TEXTURE_2D, texture[1] );
// draw the cube
glBegin ( GL_QUADS );
// Front Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
// Back Face
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
// Top Face
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Texture and Quad
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
// Bottom Face
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Top Left Of The Texture and Quad
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// Right face
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// Left Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
// finished drawing the cube
glEnd ( );
glPopMatrix ( );
// position the camera
gluLookAt ( camera.x, camera.y, camera.z, camera.x - 20, camera.y - 5, camera.z - 20, 0, 1, 0 );
// scale the world
glScalef ( 0.15f, 0.15f * HEIGHT_RATIO, 0.15f );
// render the height map
render_heightmap ( g_HeightMap );
// keep going
return TRUE;
}
Drawing/Translating Order
Author
Hello everybody,
I am sorry, I couldn't think of anything more descriptive to name this thread.
It's all about this: I am writing a small OpenGl program, that loads a height map just like NeHe does it in his tutorial. Then I added camera movement. Works fine after some little tweaking. Just how expected it to be... ;)
Now I want to draw a simple cube on the terrain. The player should be allowed to move this box/cube around using keys.
Therefore I added x, y and z coordinates for the box and every frame I make sure, that the y coordinate of the box equals the terrain y coordinate, so the box will always be drawn on the terrain.
On key press I increase/decrease the x and z coordinate accordingly.
My box just won't show up though and I strongly suspect the propblem to be in the order of my draw_scene ( ) function.
Is it true that there is a mistake in there that would somehow place my box somewhere in infinity etc. or must the mistake be somewhere else. Please respond and I'll post more code when needed.
Thanks a lot,
Jan.
[Edited by - d h k on August 7, 2005 8:14:38 PM]
Author
UPDATE: I just noted I was indeed right. The box gets drawn, but it sticks to the player, just like a weapon in a FPS shooter.
What do I have to change in the order of my function to "unsticky" it and actually have it drawn to the map (unrelated to the current camera position)? While doing previous work I managed to "unsticky" my objects by randomly placing things over each other in the draw_scene ( ) function, but this time I want to do it and actually know what is really going on...
I replied instead of editing to bump this a little... :)
What do I have to change in the order of my function to "unsticky" it and actually have it drawn to the map (unrelated to the current camera position)? While doing previous work I managed to "unsticky" my objects by randomly placing things over each other in the draw_scene ( ) function, but this time I want to do it and actually know what is really going on...
I replied instead of editing to bump this a little... :)
Try moving the gluLookAt() call to right after the first glLoadIdentity(). I'm not sure what the 'scale the world' line does, so I can't tell you where that should go exactly (it may be fine where it is).
This topic is closed to new replies.
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