# | README file for | | ELSA OGLQUERY for Windows NT 3.51 and 4.0 | | GLoria-4 | GLoria-8 | GLoria-M | GLoria-L | | Copyright (c) 1993-96 ELSA GmbH, Aachen (Germany) | | Subsidary: | ELSA GmbH ELSA Inc. | Sonnenweg 11 2150 Trade Zone Blvd. | D-52070 Aachen Suite 101 | Germany San Jose, CA 95131 | USA | | Phone : +49-241-9177-0 Phone: +1-408-935-0350 | Support Fax: +49-241-9177-213 Phone: 1-800-272-ELSA | BBS (modem): +49-241-9177-981 Fax : +1-408-935-0370 | BBS (ISDN) : +49-241-9177-7800 BBS : +1-408-935-0380 | CompuServe : GO ELSA CIS : GO ELSA | WWW : http://www.elsa.de WWW : http://www.elsa.com | | February 6th 1997, dt, sf Table of Contents: 1 Abstract 2 Running The ELSA OpenGL Query Program 3 Details For The Interested Reader ------------------------------------------------------------------------ 1 Abstract The ELSA OpenGL Query program is a tool for Windows NT to determine if the current screen resolution and color depth is capable of double buffering in hardware with the installed ELSA GLoria board. You find this program under ELSAWARE\OGLQUERY on this CD. ------------------------------------------------------------------------ 2 Running The ELSA OpenGL Query Program Start the program OGLQUERY.EXE (from the Explorer, Program Manager, File Manager, Run.. menu, or Command prompt). A message box appears with the following information of the currently running OpenGL driver: - Vendor name - Renderer name - Renderer version - OpenGL extensions in this driver - Horizontal and vertical resolution in pixels - Bits per pixel - Bytes used/needed for front and back buffer - Bytes used/needed for the depth buffer For example: (Following texts represent actual values with 8 MB VRAM and 8MB DRAM on board in 1152*864 HighColor and 1600*1280 TrueColor) a) If running an ELSA OpenGL driver: ------------------------------------------------------- Current OpenGL Driver: ELSA GLoria Installable Client Driver 2.00.03.002 GL_EXT_vertex_array GL_EXT_bgra GL_EXT_paletted_texture GL_EXT_texture_object Xres: 1152, Yres: 864, Bits: 16 3981312 bytes VRAM used for front plus back buffer. 3981312 bytes DRAM used for depth buffer. [OK] -------------------------------------------------------- b) If running Microsoft's Windows NT OpenGL GDI Generic driver: -------------------------------------------------------- Current OpenGL Driver: Microsoft Corporation GDI Generic 1.1.0 GL_WIN_swap_hint GL_EXT_bgra GL_EXT_paletted_texture Xres: 1600, Yres: 1280, Bits: 32 16384000 bytes needed for front plus back buffer. 8192000 bytes needed for depth buffer. Attention! No ELSA OpenGL driver running! [OK] -------------------------------------------------------- The OpenGL animation in the main window of the program shows a tumbling golden cube. There is no palette handling included in the program, therefore the image may be in wrong colors in 8 bit palette mode. If no ELSA OpenGL driver was found, you get another message box at the end of the program with the following text: --------------------------------------------------------- The previous OpenGL animation was not rendered using the ELSA OpenGL driver. If you have an ELSA GLoria installed the current screen resolution was not supported with hardware accelerated OpenGL and double buffering. Please consult the ELSA GLoria manual for the proper resolutions with 3D OpenGL hardware acceleration. [OK] --------------------------------------------------------- ------------------------------------------------------------------------ 3 Details For The Interested Reader If you would like to know how and why the amount of RAM on the board affects the maximum resolution in which hardware 3D acceleration with double buffering is possible, please read on. The availability of hardware 3D acceleration and double buffering on an ELSA GLoria board depends on the amount of VRAM and DRAM memory installed. The VRAM is used for the front buffer AND the back buffer. On the ELSA GLoria the complete visible screen is seen as the front buffer. To do double buffering in hardware a second, non visible screen area of the same size must be available in offscreen (the part of the VRAM which is not visible). The DRAM required for the 3D acceleration (the z-buffer) is 32 bits per pixel regardless of the color depth. The DRAM, also called the local buffer, contains the z-buffer and stencil buffer (e.g. 32 bits depth and no stencil, 24 bits depth and 8 bits stencil). This is important to remember, because in lower color depths and very high resolutions the DRAM may be the limitation of the maximum 3D screen resolution! Try this formula with your desired double buffered screen resolution: VRAM = xRes * yRes * bytesPerPixel * 2; // Front and back buffer DRAM = xRes * yRes * 4; // local buffer if (VRAM < VRAM_On_Board && DRAM < DRAM_On_Board) Double_Buffering_In_Hardware = TRUE; else Double_Buffering_In_Hardware = FALSE; Maximum resolutions and color depth for double buffered (OpenGL) hardware acceleration on ELSA GLoria boards: VRAM/DRAM Palette High Color True Color --------------------------------------------------------- 4/4 1152*864 1152*864 800*600 4/8 1600*1280 1152*864 800*600 8/8 1600*1280 1600*1280 1152*864 8/16 >1600*1280 1600*1280 1152*864 The bits per pixel value in the message boxes above represent the actual layout of the display memory. If it is stated as 16 bits the GLiNT is actually using only 15 bits for color representation. It uses 5 bits each for red, green, and blue. This is because the GLINT is capable of doing hardware dithering, which looks nicer with equally distributed color ramps. High Color is the recommend choice, if you need high resolution with double buffering. In True Color you have 32 bits per pixel, 8 bits each for red, green, blue, and alpha. This is the recommended color resolution if you use alpha blending, alpha test, or overlay planes, or need precise color values when reading bitmaps (no dithering!). ------------------------------------------------------------------------