rvp@cbnewsh.att.com (rob.v.phillips) (07/06/90)
I am interested in displaying a globe of the world on a VGA or SVGA display with a 386-25mhz machine. I will provide a mouse interface so a user can direct that the globe be rotated. I am considering using map data that provides many points that represent country borders throughout the world and throwing in some longitude/lattitude lines. For a smooth rotating effect, I expect I would need to generate 24 - 30 displays per second. I am willing to approximate country borders with line segments, to the extent that I would represent the USA borders with as few as 20 lines, if necessary; to limit a color palette to just white outlines and a black background, if necessary; also willing to show a 300X300 pixel resolution, if necessary. I am considering getting a special xxx387 co-processing chip that has harware suport of 4X4 matrix transformation. I don't have the chip specs yet, but if anyone has experience with this type of chip, I'd like to hear about it. I also have read about transputer boards, which I assume may apply to this task quite nicely, and I'd like to hear about anyone's experience with them. What hardware/software limitations for this project would I hit first? - Bus Speed? - Time to rotate, say 1000, surface points with the chip, then connect the dots with spherical conforming lines. Is slowness of floating point operations overwhelming? If so, are there any graphics packages that stick to just integer operations of newton-raphson approximations (perhaps a "FORTH" system), or that "know about" these hardware chips that do the transformations? - If a 300 (diameter) pixel globe image is adequate, is this 386 25mhz platform even close to capable of the 24 frames per sec, black & white, 1000 line segments per display? If so, what pixel diameter is the maximum I could expect to support? Thanks for any thoughts you would like to offer on this. I thought it would be wise to get advice from the experts before I dive in and start purchasing graphics packages, chips, and/or even transputer boards until I know they are necessary. I have LMI's PC-FORTH+ for my laptop, by the way, and I am impressed with it. Would the UR/FORTH graphics be a good contender for this project? Would interfacing to the special coprocessor be a breeze? Please email your thoughts or post them, at your discretion, of course. I will summarize my findings, if any are interested. Thanks! ark2!rvp - Rob Phillips