DATJN@NEUVM1.Bitnet (Jakob Nielsen Tech Univ of Denmark) (12/13/88)
I give a lot of lectures and tutorials on hypertext and usually illustrate them with "live" examples running on the Macintosh. Many of these are HyperCard stacks and use the visual effects. Unfortunately (just as on a non-2-grayscale Mac II) the visual effects have not been shown on the projected screen image used for the audience. I have used a few different transviewers (transparent screen duplicates put on an overhead projector to generate a large projected image) and until recently always had this problem. Last week I gave my tutorial at the ACM Conf. on Document Processing where they had a transviewer from Sharp - and it worked with the visual effects|| I don't know what the factors are which determine whether HyperCard visual effects are shown on a projected screen image. But until HyperCard is changed to use visual effects on all types of screens, this should be a parameter taken into account when buying screen projection hardware for your Mac.
aisl@uhura.cc.rochester.edu (Lawrence Landry) (12/15/88)
My guess is that the refresh time on your video display is not fast enough for the visual effects. I have used some displays where you can't see the mouse unless it is sitting still. A simple test is to plug in the display and move your mouse around. If it disappears, your display is not as fast as the screen. This may cause your effects to not be displayed. This all assumes that you are getting the correct effects on the Mac screen during your demonstration. Larry Landry University of Rochester
kjeld@mcopn1.csc.ti.com (12/16/88)
Jakob Nielsen Tech Univ of Denmark writes >... >Last week I gave my tutorial at the ACM Conf. on Document Processing >where they had a transviewer from Sharp - and it worked with the visual >effects|| The visual effects have always been there, you just haven't seen them. Or is that a philosophical conflict in terms? >I don't know what the factors are which determine whether HyperCard >visual effects are shown on a projected screen image. But until >HyperCard is changed to use visual effects on all types of screens, >this should be a parameter taken into account when buying screen >projection hardware for your Mac. This is not a function of HyperCard. It is a function of the screen. Liquid Crystal Displays are inherently slow. SuperTwist displays yield greater contrast. Nematic/Cholesteric (spelling?) transition yields a faster display. Some of the new displays have both features. Sharp has such a display. It can change the brightness of a pixel in about 1/9th of a second. This means that visual effects that are slower than about nine frames per second will show. Faster effects will not. There are faster displays. Either Kodak or Sony (don't remember which) has a 14 frame per second display. This is about the best you can currently expect. Some of the slower displays have better contrast ratio. In either MacWorld or MacUser (don't remember which) this month, there is a comparison of some of the available displays. For some of the slower displays, try doing your effects "very slowly" and see if they don't show up. There is nothing the authors of HyperCard can do to fix this problem. It is a hardware problem that is out of Apple's hands. Kurt Christensen Lowly Engineer @ Texas Instruments President/Chief Technical Officer @ Apeiron One of "The Rest of Us" @ Planet Earth KJELD%MCOPN1@EG.TI.COM Disclaimer: My opinions expressed here are my own and do not reflect those of Texas Instruments Incorporated. They do, however, reflect those of Apeiron, since my partners believe everything I say. The Rest of Us will have to speak for them selves. ***