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IvanScheers

Displaying 2D Bitmap

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Hi, I''m trying to find examples of how to display a 2D bitmap in an ortho screen. Silly thing is I know how to do if they''re in a display list (as for bitmapped fonts), but I can''t find anything on doing it for a single bitmap (texture). It works in 3D space, but then putting them at exact screen locations is more difficult. Anyone know of an example or which OpenGL routine to use instead of the glListBase & glCallLists to display a single bitmap in 2D space ? Thanks, Ivan Here''s the code (based on NeHe''s) that works for a list : GLvoid isDisplayBitmap(GLint x, GLint y, char BitmapID, float scale) { // we''re using a display list, originally intended for fonts, // which expects a string, while we''ll only be passing 1 char as // the bitmap id, so make it into a 2 character string // Not the most elegant solution, but it works... char bitmap[2]; bitmap[0]=BitmapID; bitmap[1]=0; // set up for rendering bitmaps glBindTexture(GL_TEXTURE_2D, texture); // Select Our Bitmap texture glDisable(GL_DEPTH_TEST); // Disables Depth Testing glMatrixMode(GL_PROJECTION); // Select The Projection Matrix glPushMatrix(); // Store The Projection Matrix glLoadIdentity(); // Reset The Projection Matrix // following line needs the parameters for glortho // passed based on the scale (see in is_Font.cpp how to do that) int v_width, v_height; if (scale == 100.0f) { // for 100% scale, assigning is faster than computing // like what is done for scaled display v_width = VIRTUAL_WIDTH; v_height = VIRTUAL_HEIGHT; } else { // compute the size of the ortho screen, // so the bitmap will be displayed scaled // bigger values for v_width & v_height means smaller bitmap v_width = (int)((float(VIRTUAL_WIDTH) * 100.0f) / scale); v_height = (int)((float(VIRTUAL_HEIGHT) * 100.0f) / scale); } glOrtho(0,v_width,0,v_height,-1,1); // Set Up An Ortho Screen (depending on scale) glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix glPushMatrix(); // Store The Modelview Matrix glListBase(base); // Choose The Font Set (0 or 1) glLoadIdentity(); // Reset The Modelview Matrix glTranslated(x,y,0); // Position The Bitmap (0,0 = Bottom Left) glCallLists(1,GL_BYTE,bitmap); // Place the bitmap on the screen glMatrixMode(GL_PROJECTION); // Select The Projection Matrix glPopMatrix(); // Restore The Old Projection Matrix glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix glPopMatrix(); // Restore The Old Projection Matrix glEnable(GL_DEPTH_TEST); // Enables Depth Testing }

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I thought that there was a NeHe tutorial on displaying bitmaps, that doesn''t use the glList stuff. :S

Check all the tutorials for image loading, I''m sure you''ll find something. =)

-Fredric

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