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Text File | 1986-11-21 | 16.4 KB | 327 lines

C-LIGHT Copyright © 1987 by Ronald A. Peterson This is a demonstration copy of a scene editor and ray tracing program called C-Light (version 1.0). For those not familiar with ray tracing, it is a technique whereby very realistic three dimensional pictures of objects can be created by tracing the paths of rays of light through a scene. The unique features of C-Light include: * Full Intuition interface for ease of use. * Simple and quick scene creation using a powerful editor that lets you visually place objects. * Allows creation of scenes with up to 170 objects (spheres, cylinders and cubes) each of which can be sized, rotated and located independently in all three dimensions. * Allows any number of light sources (up to object limit of 170) with variable intensity and adjustable ambient light. * Supports overscanned and interlaced-overscan images as well as 320 by 200 and 320 by 400 images, all in the standard IFF format. * Smoothly shaded objects with the color set selectable out of 4096 possible colors. * Reflecting surfaces (mirrors). * Shadows. * Movable viewpoint (the observers eye.) * Easy editing of scenes both during and after creation. * Multitasking. C-Light differs from other ray-tracers that have recently appeared in that it is extremely simple to use. It requires no knowledge of three dimensional geometry (except that which you were born with) and presents the user with an interface similar to that found in the better paint programs available today. In addition, C-Light can easily produce smooth curved shapes such as spheres, ellipsoids, and cylinders that are difficult to construct using polygon based systems. C-Light is made up of several parts or modules. The C-Light scene editor allows the user to create a three dimensional scene using simple primitive objects (currently spheres, cylinders, and cubes.) These objects can be interactively placed, stretched, shrunk and rotated using a very friendly mouse oriented interface. The C-Light ray tracer then takes this scene description and calculates the resulting picture based on the locations of the objects, light sources, and eyepoint. Both overscanned and PAL (European) formats are supported, with or without interlace. These pictures can then be saved to disk as IFF picture files and viewed using the View utility which is provided. All programs are multitasking and will use fast RAM in place of chip memory where possible. This copyrighted version of C-Light is freely redistributable so long as it is not sold for profit or modified in any way and is accompanied by this text file which describes the software and its source. All rights are reserved and reside with its author, Ronald A. Peterson. Since C-Light is a commercial product currently being marketed, this demo version is slightly limited in that the object editor will only allow the user to place ten objects in a scene. Anyone wishing to purchase a complete copy (which allows placing up to 170 objects, includes complete documentation and is not copy protected---as yet) can do so by sending $59.95 to: Ronald Peterson P.O. Box 614 Milford, NH 03055 Since C-Light is being independently marketed (inquiries from distributors are invited) please distribute this demo freely. Posting to bulletin boards is also encouraged so long as this text file remains with the software. This version is already available on BIX and PeopleLink. Formalities aside, here is a brief description of how to use C-Light: It is necessary to use V1.2 of Workbench with C-Light and a Preferences setting for eighty column text is desirable. C-Light is a complex program; if run on a 512K Amiga, it will require almost all memory to be available. This means that you should have as few other windows as possible open and no other programs running. Usually a requestor will warn you if there is not enough memory when calling up a function but in extreme cases the program may refuse to put up the requestor you have asked for. This is not a fatal condition---just pop to the back screen and close some windows and you will be able to continue working. The most likely place for this to occur is when calling up the Get File requestor in C-LightII when in the interlaced-overscanned screen mode. On an Amiga with more than 512K RAM, C-Light will gracefully multitask with only a few side effects: 1) Calculating an interlaced picture will cause all screens to be interlaced. 2) Because of some peculiarities involved in opening overscanned screens, if you notice a moving striped bar on the right edge of the screen or if the mouse pointer changes to some weird shape, you can remedy it by using Preferences to better center the screen. This will only occur if you have moved the Preferences screen center to the extreme far right or left however. 3) Programs that use sprites might be affected since overscanned pictures sometimes intrude on sprites. C-Light makes extensive use of Intuition (gadgets, sliders, menus, etc.) which means many functions can be easily understood just by trying the gadget or slider to see what it does. The programs can be run from Workbench or from CLI. C-Light is in two parts (C-LightI and C-LightII) and also includes two utilities: Video and View. *---VIDEO ---* Calling up Video allows you to select screen resolution and PAL or USA compatability by responding to requestors which ask yes or no questions about your choices. (Note that Video has no effect on pictures that have already been generated.) *--- C-LightI ---* C-LightI is the scene editor. Upon calling it up you will see some gadgets on the right side of the screen and a title bar. There is a drag-down menu attached to the left side of the title bar. This is the utilities menu which contains the following functions: Hide Title Bar - Hides/restores the title bar. Hide Selectors - Hides/restores the gadgets on the right. New Directory - Change directory (drawer) or disk. Colors - Lets you change the CURRENT screen colors, not the colors used in the scene. Reset All - For starting a new scene. Load file - Load in a scene file. Save file - Save a scene file. Exit - Go have a look in the fridge. Most of these menu selections call up requestors. The use of these requestors conforms to the rules outlined in the "Introduction to Amiga" manual. Try loading in and playing with the example scene file included with the demo which is entitled "Columinaire". The function of the gadgets on the right side of the screen will be covered next: BALL, CUBE, CAN - When clicked on, these gadgets will cause an outline (wireframe image for the technical among you) of the corresponding object to appear. Using the mouse you can move the object left/right or up/down. By clicking the right mouse button (when the cursor is NOT over the title bar) the object can be moved in/out in depth with the mouse instead of up/down. Clicking the right button again will restore up/down movement. Because the space in which you are moving the object is much larger than the screen of the Amiga, the object does not follow the cursor position. For example, if the object is in the center of the screen and the cursor is on the right edge of the screen, you can keep moving the mouse to the right (picking it up and moving it, picking it up and moving it, ...) and even though the cursor doesn't move, the object will keep moving to the right eventually going off the screen. A mouse is inherently a device for manipulating two dimensional objects so this is how I turn it into a 3D manipulator. You can think of the object being moved as a new, three dimensional cursor for the mouse if you like. As you are moving the object around you will see the X, Y, Z coordinates of the CENTER of the object being displayed in screen coordinates. Once you have the object somewhere near where you want it, click the left mouse button and the Object Modification Requestor will appear. (Fancy name eh? I thought that one up myself.) The sliders on this requestor let you change the size of the object in the X, Y and Z directions and allow you to rotate the object around the X, Y and Z axis. The gadgets labeled A, B, C, M let you pick the color for the object. I will discuss later how to set these colors to whichever out of the 4096 possible colors that you choose and how to set the background color for a scene. The "M" gadget makes the object have a mirror (almost perfectly reflecting) surface. Hit the CANCEL gadget if you decide you don't want the object. The requestor can be moved by dragging it via its title bar. You can still move the object around when the object modification requestor is present by clicking with the left mouse button anywhere outside the requestor. The requestor becomes inactive and you can then move the object around using the mouse, just as you did before the requestor appeared. Clicking the left button again activates the requestor again and stops the object from moving when you move the mouse. In this way you can alternate between moving the object and sizing or rotating it until you have it exactly as you want it. Then, hit the close gadget in the upper left corner of the requestor and the requestor will disappear and the object will change color indicating that it has been set in place. DEL, CHG - Once you have placed an object you can still change it. Hit the DELete gadget and then click on the CENTER of the object you want to delete with the left mouse button. The object will be highlighted in a different color and a requestor will ask if this is the object you really want to delete. The CHG gadget works in a similar fashion. Hit CHG, then click on the object you want to change. It will be highlighted in a different color and the object modification requestor will appear. From then on you can treat everything just as though you were placing the object for the first time. VIEW - Once you have defined a scene you can use this gadget to move, rotate, stretch or shrink the scene as a whole. Click on it and you will see the scene disappear, then a cube and the object modification requestor take its place. Imagine your scene is inside this cube. You can then rotate it, move it, and size it. Hitting the close gadget on the requestor will cause the scene to be redrawn using the new view. This is also useful for rotating a scene to get at and change the parts of it that are in back of other objects. EYE - This allows you to set how close or far the observers eye is from the scene. It uses the object modification requestor again and works just like moving your own eye nearer or further from a window (the screen of your monitor being the window.) As you move closer to the window you can see more of the scene. It also becomes more distorted by perspective (an effect like a fish eye lense on a camera.) As you move further away you can see less of the scene through the window and things become less distorted and more natural looking. Currently the eye point can only be moved closer or further away; I may add up/down and left/right movement to it if it seems useful. Clicking on the close gadget will cause the scene to be redrawn using the new eyepoint. COLR - This gadget calls up a requestor that allows you to change the color of the OBJECTS. It does not affect the current colors used on the screen. This is where the colors A, B, C and the background color are determined. The colors you pick for A, B, and C are the colors that will be used in your object at its brightest spots. The brightest spots will be those closest to the light sources. The rest of the object will be in blacker shades of this color, getting dimmer the further that part of the object is from the light. (Just like in real life!) LITE - This gadget allows you to place light sources in your scene. A light is treated just like an object (BALL, CUBE, CAN) and is placed in the same way. Sizing and rotation of light sources has no effect on the picture. Lights are point sources that radiate in all directions. The only limit on the number of light sources is the limit on the total number of objects (10 for this demo version, but then there would be no room for objects.) More lights means a longer calculation time though. *--- C-LightII ---* Once you have created a scene and saved it to disk, the second part of the program comes into play - C-LightII. C-LightII is the part that actually draws the scene. Ray tracing is a complex mathematical process so this can take some time - from a half hour up to several days. When you call up C-LightII you will see a requestor. Hitting "Get File" calls up a directory requestor that allows you to select the scene you want to calculate. (If you have trouble getting the directory requestor to appear you need to free up some memory and try again.) After picking a scene you can set some of the overall characteristics of the scene with the sliders and gadgets: LIGHT slider - This sets the intensity of all the lights in a scene. The number displayed near the slider is the range at which the lights will be at half intensity. AMBIENT slider - This sets the background level of light that illuminates ALL objects equally. BLEND slider - This one controls how much blending together of colors occurs. Given ten shades of each color with which to shade an object, randomly blending them a little makes the picture look smoother. Too much and your picture will be lost in fuzz. Too little and you will see bands of color. ALIAS gadget - Turning this on enables anti-aliasing. This is a simple algorithm that tries to lessen the effects of jagged edges (caused by the fact that the screen is made up of a limited number of rectangular dots.) It doesn't always improve the picture. SHADOW gadget - Turning this gadget on will cause shadows to be calculated for the scene. Shadows are VERY time consuming and can easily cause a complex picture to take days to calculate, particularly if there are many light sources. SAVE gadget - This allows you to name and save the created picture as an IFF file. The save requestor will also come up automatically when the picture is done. You can get back to the main requestor at any time (in order to exit, change settings or save an unfinished picture) by clicking once with the left mouse button anywhere in the lower three quarters of the screen. *--- VIEW ---* Finally, the VIEW program is an IFF picture viewer that allows you to look at the saved IFF picture files (overscanned ones too!) To view a picture from Workbench you can either just double-click on the pictures icon or click once on the pictures icon while holding down the left Amiga and Shift keys simultaneously, then double click on the View icon. From CLI you can type: VIEW 'picture' where 'picture' is the name of the file you want to see (without the '.ilbm' extension.) Click anywhere in the upper left corner to end it. So...that should be enough to get you started. I have tried to make this program as simple to use as possible, modeling it after paint programs like DeluxePaint. In fact, because shading is a tough thing to do with a mouse, C-Light makes a nice addition to paint programs since it lets you easily create backgrounds of shaded 3D objects. Have fun with this demo version and if you like it, send a check my way and tell a friend about it! Let me know of any bugs that you find and I will correct them and repost a new demo version (and maybe send you a free copy of C-Light if you find something serious.) Also, not having a European Amiga, I have not been able to test overscan while in PAL mode. I would appreciate knowing if it works. Future enhancements will be offered for a small fee to registered users and will include: More object primitives - Cones, Half spheres, Trapezoidal patches. Specular reflections (glossy surfaces) Better memory management. Animation editor & viewer - for making short, animated movies on the Amiga (in the ANIM format) or long animated movies on film or video tape. Amiga, Workbench and Intuition are trademarks of Commodore-Amiga, Inc. DeluxePaint is a trademark of Electronic Arts.