SurfaceWeenie.txt created 2/16/93 ============================================================================= Welcome to SurfaceWeenie! A project I started to figure out just what was going on in Imagine 2.0's rendering engine. The IFF images I created should help you in two ways... 1) Give you a good reference for specular highlight values. 2) Make you wonder if even Impulse understands what the rendering engine is doing. (It really hasn't changed since Turbo Silver has it?) There are three (3) 16 color IFF image files in this archive. 1.Hardness.iff 2.Shininess.iff 3.ShinyFilter.iff ============================================================================= I will now go forth and try to explain what each one exemplifies. 1.Hardness.iff This is pretty simple to explain and is probably that image that will do you the most good. (If any help you at all) The top 10 balls show values ranging from 0 to 255 of the Hardness setting. Doesn't do what you might expect. It basicly changes the size of the specular highlight with 255 being the the smallest. (i.e. hardest) The way they rendered, it looks like the highlight is shifted left of where it should originate. Wouldn't this setting be better described as specularity? Also, A low Hardness isn't diffused like a "softer" object would be. The Hardness values will have no effect unless you have some amount of Specular color (the upper 10 balls had values of 255,255,255 (white)) The Specular settings are actually just color settings for the Hardness. (Interesting how the words Specular and Hardness get mixed up here, eh?) The lower 10 balls show the changing of the Specular color from Black to White. Notice that lower values fade out the Specular highlight (It won't create a black specular highlight) Now if you were actually affecting the "hardness" of an object, wouldn't it effect the ENTIRE object? This is why I feel that "Hardness" is a misnomer. It's actually Specular. A "real" hard object would reflect less light across it's entire surface. A "real" soft object might have less specular highlight, but it would look less modelled and more flat. OK now that I've got that off my chest, you might like to know just how to actually change the "Hardness" (by my definition) of an object. Look no farther than... ============================================================================= 2.Shininess.iff The first thing I learned about Shininess is that the slider is pretty much worthless. It only acts as an On-Off switch for cryin out loud! Remember in the 2.0 manual... They say to bring up Shininess to "any" value? Any value other than ZERO turns on this feature. The actual control of the Shininess is done by the Index of Refraction number. Once you turn on Shininess the object is no longer capable of being transparent, so the refraction number now changes the hardness (again, my definition). A refraction index of 1.0 (in the context of hardness) is no different than if the shininess were to be turned off. (A shininess value of 0 would be off) As the Index of Refraction value is increased, (to it's limit of 3.55) the object begins to reflect less light ACROSS IT'S ENTIRE SURFACE. Also note, the Specular highlight doesn't change! Now that is strange! Now it gets stranger! The Imagine book describes the Shininess as a film of glass over your object. (Huh?) Well I've already shown you ONE thing Shininess does, now here's another. The Filter colors ALSO interact with the Shininess! Increasing the filter color from back will make your object REFLECTIVE! (Double take time) I only find this slightly redundant! The upper 10 balls of this image (2.Shininess.iff if you have forgotten) show only the changing of the Index of Refraction value in it's relationship to the Shininess (hardness damit!). The lower 10 balls again are Index of Refraction but with the FILTER values at 255,255,255. Remember, the filter values are now changing the REFLECTIVITY! Are you confused yet?!?! ============================================================================= 3.ShinyFilter.iff This is the third, final, incomplete image that continues where 2.Shininess.IFF left off. All the same rules apply here. This time I'm leaving the Index of Refraction at 3.55 (Full tilt) and now adjusting the Filter RGB values from 0,0,0 to 255,255,255 (Black to White) You will see the reflection go from none to full. It's just to show that they interact and that they differ in how they act upon the object. I think I had planned to put somthing above the 10 lower balls, but I now forget what. (listen, I made these images about a year ago OK? :) The reflections are provided by a Global reflection map as defined in the ACTION editor. There is no ray-tracing here. (Although I would guess the effects would be similar as the ray-tracing effect of tranparency is nulled when you turn on Shininess) This brings me to another point... (Oh no, not more!) The reflection map image was a large checkerboard. How on THIS Earth are you able to see past the axes of a sphere??? Notce in the reflected spheres that you can see beyond where Imagine is wraping the tops and bottoms of the image map ON BOTH AXES!!! If I was slightly above the equator of the sphere, I might see the image wraped to a point and a little beyond on the north pole. I wouldn't be able to see the south pole. I was looking straight at the center of the sphere in my renderings. ============================================================================= I hope I was clear in my explaination. I don't know if this is stuff that is covered in Whorley's (sp?) "Understanding Imagine" book or not, as I've not read it. Anyway I hope this has been somewhat helpful. If you think I may be incorrect, I'm interested in hearing. Especially the Shininess slider! I tried to detect any change in the renderings and in the resulting file sizes. I could not! Even with the refraction values up, SHININESS 0 would be different than SHININESS 1. But from 1 to 255, SHININESS didn't do anything. This leads me to read between the lines of the manual and conclude that it's only an On-Off switch. Each individual sphere is from a separate rendering. A ten (10) frame animation was created by morphing two physically indentical spheres with only surface attributes changing. Each resulting 24 bit image was converted to 16 color IFF via ADPro and pasted in DeluxePaint III. Perhaps we should all "Ask Zack for more here" :) Send all complaints to >NIL: Scott Thomas Associate Director/Studio Manager WBBH TV20 Fort Myers, FL