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krogoth

OpenGL OpenGL 2D quads don't render right

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As a part of my engine, I want to load fonts from files in a custom format where each character is stored as a greyscale image and render them as 2D quads with textures. To show the text, I want to set a color and then have the texture go from that color when the pixel is white to transparent - the greyscale image should be the alpha channel and the RGB should be set to whatever I want. When I try out the code, everything renders real nice, and all the characters are in the right place and have the right size, but each quad that should hold a character is either green (my color) or black, depending on the code I''m using. Does anyone know what could be doing this? In case it helps, I explain my code and how I know the data is right below. I start the OpenGL initialization with this code: glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glEnable( GL_CULL_FACE ); glCullFace( GL_BACK ); glDepthFunc( GL_LESS ); glEnable( GL_DEPTH_TEST ); glEnable( GL_LINE_SMOOTH ); glEnable( GL_POINT_SMOOTH ); glEnable( GL_POLYGON_SMOOTH ); glEnable( GL_BLEND ); glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ); glEnable( GL_TEXTURE_2D ); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT ); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT ); Then, before rendering the text, I do: glMatrixMode( GL_PROJECTION ); glPushMatrix( ); glLoadIdentity( ); glOrtho( 0.0f, (GLfloat)(vid_screenWidth), 0.0f, (GLfloat)(vid_screenHeight), -1.0f, 1.0f ); glMatrixMode( GL_MODELVIEW ); glPushMatrix( ); glLoadIdentity( ); glDisable( GL_DEPTH_TEST ); glDisable( GL_CULL_FACE ); vid_screenHeight and vid_screenWidth are the resolution of the window. I start the text rendering with a few things that could be put in other places: glPixelStorei( GL_UNPACK_ALIGNMENT, 1 ); glPushAttrib( GL_PIXEL_MODE_BIT ); And then I have this, which should set the color of the pixels but doesn''t do anything (color is an array of floats): glPixelTransferf( GL_RED_BIAS, color[0] ); glPixelTransferf( GL_GREEN_BIAS, color[1] ); glPixelTransferf( GL_BLUE_BIAS, color[2] ); For each character, I do this (where font->data[cc] is the : glBegin( GL_QUADS ); glTexImage2D( GL_TEXTURE_2D, 0, 1, font->fullWidths[cc], font->fullHeight, 0, GL_RGB GL_UNSIGNED_BYTE, font->data[cc] ); glColor3f( color[0], color[1], color[2] ); color[1] -= 0.15f; #define TEXTURE( x, y ) glTexCoord2f( x, y ); printf( "Texture at %f %f\n", x, y ) #define VERTEX( x, y ) glVertex2f( x, y ); printf( "Vertex out at %i, %i\n", x, y ) TEXTURE( 0.0f, 0.0f ); VERTEX( deltaX, y ); TEXTURE( xfar, 0.0f ); VERTEX( font->widths[cc] + deltaX, y ); TEXTURE( xfar, yfar ); VERTEX( font->widths[cc] + deltaX, y - font->fontHeight ); TEXTURE( 0.0f, yfar ); VERTEX( deltaX, y - font->fontHeight ); glEnd( ); deltaX += font->widths[cc] + font->charSpacing; xfar and yfar are the texture coordinates of the corners of the text and deltaX is the left position of the character. fullWidth and fullHeight are the dimensions the character is stored at (multiples of two), and I use xfar and yfar to set the actual dimensions of the character. And after I''m done, I do this: glPopAttrib( ); // in another function... glEnable( GL_CULL_FACE ); glEnable( GL_DEPTH_TEST ); glMatrixMode( GL_PROJECTION ); glPopMatrix( ); glMatrixMode( GL_MODELVIEW ); glPopMatrix( ); I have some debugging output in addition to what is shown above, so for the ''!'' character, I get this (including an ASCII art rendering with each pixel as blank for black and 1-9 showing the intensity): Character !: | | 46 | 69 | 69 | 68 | 46 | 36 | 12 | 992 | 571 | | | | | | ----| Used color 0.000000, 0.100000, 0.000000 Texture at 0.000000 0.000000 Vertex out at 51, 476 Texture at 0.750000 0.000000 Vertex out at 54, 476 Texture at 0.750000 0.812500 Vertex out at 54, 463 Texture at 0.000000 0.812500 Vertex out at 51, 463 Here you see the character image is 4 pixels wide and 16 tall (powers of two), and it shows the texture and vertex co-ordinates used. You can see the best-case output (green squares instead of black) at http://www.garandnet.net/text.png. As you can see, the quads have the perfect position and size, but the wrong texture.

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Could be caused by the blending. You might try using .tga files also since they can be 32 bit 24 bits color and 8 grayscale for transparency its really easy to do if you have photoshop once you have that I would use glEnable(GL_ALPHA_TEST); and then glAlphaFunc(GL_GREATER, 0.1f); this will make any black on the grayscale transparent and anything other then black transparent how it is now it sounds like the colors from the background of your tiles are blending with the scenery color. Hope this helps if ya need more help just say so

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