june/july 1996 GAME DEVELOPER MAGAZINE GAME PLAN GGAMEAEM Editorial Director Larry O’Brien [email protected] Senior Editor Alex Dunne [email protected] Reboot Managing Editor Diane Anderson [email protected] Editorial Assistant Jana Outlaw [email protected] o, there’s nothing wrong with future versions of DirectX SDK, it Contributing Editors Barbara Hanscome [email protected] your dials. You may have been would make sense to have a base to Chris Hecker expecting Larry O’Brien’s build upon. Besides the articles in this [email protected] sagacious words in this space, issue on the Windows 95 Game SDK, David Sieks and here you are reading a we’ll feature three articles in the next [email protected] column by the guy who for- issue on DirectDraw, DirectInput, and Web Site Manager Phil Keppeler merly wrote Crossfire. “Just Direct3D. Though our demographics [email protected] what the heck is going on?!” indicate that most of our readers work Editor-at-Large Alexander Antoniades [email protected] Nyou might be asking. on games for Intel-based machines, Changes are afoot here at Game we’ll also add more diverse platform Cover Photography Charles Ingram Photography Developer, though nothing so radical as coverage. We’ll be devoting coverage to a Spindler reorg. Larry’s been kicked the upcoming Macintosh Game SDK Publisher Veronica Costanza upstairs to editorial director, which for those of you working on Mac Group Director Regina Starr Ridley means that he gets to lean back in his games. Special Projects Manager Nicole Freeman chair and watch pandemonium unfold, Beginning this fall, we’ll review [email protected] rather than having to dive into the mire development tools. The first review was Advertising Sales Staff with the rest of us. Oh, and he’s also going to cover C++ compilers, but, Western Regional Sales Manager doing a lot more programming (some wouldn’t you know it, Chris Hecker Steve Nikkola (415) 905-2256 people get to have all the fun). So, stole my thunder with his latest series [email protected] instead, I’ve taken over much of the on compilers. But look for reviews of Promotions Manager/Eastern Regional Sales Manager day-to-day housekeeping here at the various 3D animation and C++ tools. Holly Meintzer (212) 615-2275 magazine. As with every byte of content that [email protected] Now that I’ve been entrusted with goes into the magazine, let us know Marketing Manager Susan McDonald a smidge of power, my first goal is to what appeals to you and what doesn’t. Marketing Graphic Designer Azriel Hayes work towards beefing up the number of Want more space in the magazine Advertising Production Coordinator Denise Temple articles every issue. More bang for your devoted to articles, and have us post Director of Production Andrew A. Mickus buck. I’m going to try to squeeze every code on our FTP site instead of taking Vice President/Circulation Jerry M. Okabe inch of this magazine to fit as many up space on the pages? Or perhaps you Circulation Director Gina Oh articles as possible into upcoming want more code in the magazine and Associate Circulation Director Kathy Henry issues. As my previous beat was indus- fewer articles. Are there any subjects that Group Circulation Manager Mike Poplardo try news and analysis, this column will we haven’t covered that you’d like to read Assistant Circulation Manager Jamai Deuberry address these issues, and the Crossfire about? Let us know either through our Newsstand Manager Debra Caris column will slowly fade into the sunset. web site, http://www.gdmag.com, or Reprints Stella Valdez (916) 729-3633 This issue, we examine Microsoft’s pick up a pen and scribble us a note. DirectX II SDK. If you haven’t looked I’ve just returned from the Com- Chairman of the Board Graham J.S. Wilson at the SDK yet, check out Robert puter Game Developers Conference in Chairman/CEO Marshall W. Freeman Hess’s article on page 24 which pro- Santa Clara, Calif., which was more President/COO Thomas L. Kemp vides an overview of the kit. If you’ve packed with people than ever before— Senior Vice President/CFO Warren “Andy” Ambrose already started down the DirectX trail, close to 4,000. Check out the Bit Blasts Senior Vice Presidents David Nussbaum, Darrell however, this article may be slightly column, as well as our web site for Denny, Donald A. Pazour, Wini D. Ragus remedial. Don’t fret, Game Developer information about new products that Vice President/Production Andrew A. Mickus ■ isn’t reneging on its commitment to were launched at the show. Vice President/Circulation Jerry Okabe high quality, technically deep content. Vice President/ We did feel, however, that since there Software Development Division Regina Starr Ridley is going to be substantial coverage in Alex Dunne Miller Freeman the magazine about the current and Senior Editor A United News & Media publication 6 GAME DEVELOPER • JUNE/JULY 1996 http://www.gdmag.com SEZ U! Exploring the World of Texture Mapping KEEPING CHRIS ON HIS TOES! ded in the bottom, but we want to get rid of the such fast texture mapping, while also doing top garbage. To do this, we just subtract our game AI, Z buffering, and anything else that Dear Editor: “big number” (your 1.1 * 223) from this as an needs to be done? When it changes detail level, ’ve enjoyed reading Chris Hecker’s series on integer: what is it doing? perspective texture mapping. His articles were Ivery informative, and they were very timely Stuart Doyle with respect to my current project. Thanks! 11001011001111111111111111111000 Via e-mail However, there are a few things in the - February/March 1996 issue that confused me. 01001011010000000000000000000000 First, on page 24, Figure 3, should the resulting = Chris Hecker replies: exponent have the same binary exponent value 11111111111111111111111111111000 Well, general quads will work with a projective as the higher magnitude value? In this case (Which equals -8) mapping (they won’t with affine). But, if your 10000111 (135)? quads (or even general polygons) are coplanar, Also, in the first paragraph of page 24, he Thanks a lot! Keep up the good work! you can use the plane equations to generate the talks about subtracting “the integer representa- gradients without using the vertex texture coor- tion of our large, floating-point shift number dinates. The math is a bit much, but I might from the integer representation of the number X MODE MARKS THE SPOT cover it in a later article. You can derive it your- we just converted....” What are these numbers? Dear Editor: self if you think about what you need to describe The values to be subtracted are now: our magazine is great! I use a lot of the the plane of the texture (a vector from the origin articles constantly. Especially the ones to the texture origin, a U direction vector, and a 0 | 10010110 | 10000000000000000000000 about breaking into the game business. It V direction vector, all in view space). Solve for u 23 Y (1.1 *2 ) actually helped me land a job! and v in terms of screen space x and y (which - Your X mode programming optimizations are view point x/z and y/z) and you’ve got it. 1 | 10010110 | 00000000000000000001000 (Our 8.75 lined up) were great. Thanks for producing a much need- You’ll end up with rational linear equations that = ed magazine. look like: 1 | 10010110 | 11111111111111111111000 John Bryant (This gets us our -8) Via e-mail u = (ax + by + c)/(dx + ey + f) u = (gx + hy + i)/(dx + ey + f) I think this is correct! Kenneth Chao I HAVE A TEXTURE MAPPING QUESTION! Also, Descent doesn’t Z buffer. The major Via e-mail Dear Editor: speedups in real games come from novel data- ’ve been getting Game Developer magazine base traversal algorithms that cull out most of since March 1995, and I’ve been especially the world before they gets to the texture map- Chris Hecker replies: Ifollowing your series on texture mapping. per. The fastest texture mapped triangles are Yes, this is a bug, thanks for spotting it! I must Do you have any suggestions on how I could the ones you didn’t draw. have cut and pasted when I did the make a quad texture mapper, assuming that diagram. the points are clockwise and coplanar? Theoret- In regards to integer presentation, you have ically, it should not be too much of a problem, Say It! got one bit wrong in your result. The .1 bit gets since the gradients across the quad are the Please send all feedback to: Game Developer borrowed from, so you end up with: same as either of the two triangles which make magazine, Feedback, 600 Harrison St., S.F., it up, or at least, should be, as far as I have 1 | 10010110 | 01111111111111111111000 Calif. 91407 or to [email protected]. reasoned. Thanks! Now, we’ve got a result that has our -8 embed- Also, how do games like Descent manage http://www.gdmag.com GAME DEVELOPER • JUNE/JULY 1996 9 SEZ U! Exploring the World of Texture Mapping KEEPING CHRIS ON HIS TOES! ded in the bottom, but we want to get rid of the such fast texture mapping, while also doing top garbage. To do this, we just subtract our game AI, Z buffering, and anything else that Dear Editor: “big number” (your 1.1 * 223) from this as an needs to be done? When it changes detail level, ’ve enjoyed reading Chris Hecker’s series on integer: what is it doing? perspective texture mapping.