Windows 95 Secrets (4th Edition)/Windows95Secrets4thEdition.iso/tools/graphics/render/rdcfaq.tx_/rdcfaq

Text File | 1996-05-12 | 5.9 KB | 124 lines

RenderDotC Frequently Asked Questions List
==========================================

Table of Contents:

1. Getting better color
2. Choosing an interface
3. Using the programmer's interface


   1. Getting better color
   -----------------------

Q: What's the difference between palette-based and RGB graphics modes?
A: The Windows desktop and all of the open windows on it use the current
   graphics mode of your video card.  There are two broad categories of
   graphics modes: palette-based and RGB.

   In a palette-based mode, a small set of colors (typically 256) are loaded
   into the system palette.  These colors must be shared by all of the windows
   on the desktop.  Often, windows compete with each other for control of the
   system palette.

   In an RGB mode, each window has full access to the color spectrum.  In RGB
   modes, the more bits per pixel, the higher the quality.  Typical values for
   the number of bits per pixel are 15, 16, 24, and 32.  While better in
   quality, RGB modes consume more CPU and memory resources.

Q: Why does my image have so few colors while rendering?
A: In palette-based modes (see previous question), RenderDotC waits until the
   image is completely rendered before it loads the system palette.  While
   rendering, it uses a very crude approximation to the final color.  Once the
   image is rendered, RenderDotC tries to pick the 256 colors which best
   represent the entire image.  At this point, you should see the image snap
   into focus.

Q: Why does my image still have poor color after rendering is complete?
A: First, make sure you point to the image in question and click.  It could be
   that the system color palette was compromised by a competing window.
   Selecting your image will give it control of the system palette.

   If that doesn't work, consider switching your Windows desktop to an RGB
   graphics mode with more bits per pixel (see next question).

Q: How do I switch my Windows desktop graphics mode?
A: Under Windows '95: start Help; click the "Index" tab; pick "resolution,
   monitor"; pick "Changing your screen resolution"; click the arrow where
   it says "Click here"; follow the instruction specific to your system.  You
   will have to restart Windows.  You may have to sacrifice resolution in
   order to get more bits per pixel.

Q: How do I create images with more bits per pixel than my Windows desktop?
Q: How do I create images with higher resolution than my Windows desktop?
A: Save your images as TIFF files by using rdcOutputFile.  For example, use
   the following RDC bytestream commands to save an image as a 48 bit per
   pixel RGB TIFF file:

       rdcOutputFile "tiff" "myimage.tif"   # Save as TIFF file
       rdcColorQuantize 65535 0 65535       # Use 16 bits per color sample

   Note that the demo version is incapable of saving image files.

   2. Choosing an interface
   ------------------------

Q: Which of the four interfaces should I use to describe scenes?
A: The RenderDotC programmer's interface.  You get all the power of C/C++
   language such as loops, conditions and functions.  You may then link
   with the RDC bytestream library to convert your scene to an RDC file
   automatically.  If you don't have a compiler, then use the RDC bytestream
   interface directly.

   Please don't rely on the two RenderMan interfaces.  They are provided to
   convert existing models and may not be supported in future releases.  It
   is better to learn the RenderDotC interfaces now.

Q: Where can I find out more about the interfaces?
A: The RenderDotC interfaces are best described by the online reference manual.
   It is cross-indexed in two ways: as a user's guide with introductory
   material and functions listed by category; and as a reference manual with
   functions listed alphabetically.

   For more information about the RenderMan interface and for a good treatment
   of the concepts of photorealistic rendering, see "The RenderMan Companion"
   by Steve Upstill.

   3. Using the programmer's interface
   -----------------------------------

Q: Why can't I link to the rendc.lib and rdc.lib libraries?
A: The libraries were created with Borland C++ 4.52 and may be incompatible
   with other compilers.  However, you may still use the DLL's by using one
   of the following two methods:

   1: You can replace rendc.lib and rdc.lib with import libraries compatible
   with your compiler.  Find the tool which creates import libraries from
   DLL's (typically called "implib.exe").  Run the program on rendc.dll and
   rdc.dll which are in the RDC .\bin directory.  Put the resulting .lib files
   in the RDC .\lib directory.

   2: You can load the DLL's manually from your C/C++ program using the Win32
   LoadLibrary() function call.

Q: How can I link to the ri2rdc.lib library?
A: If your compiler doesn't recognize the format of this library, your out of
   luck.  Unfortunately, the  RenderMan Interface includes exported global
   variables, and thus cannot be a DLL.

   Try to get access to a workstation with a RenderMan client library,
   link your program to it, run it, bring the resulting RIB file to RenderDotC,
   and run it through wrib2rdc.exe.  Barring that, try converting your program
   to use the RDC interface.  It could be a good learning experience.

Q: Why do I get a version error on the Borland runtime libraries?
A: If you have Borland C++ installed on your system, then the RDC \bin
   directory needs to be ahead of the Borland \bin directory on your PATH.
   Edit your autoexec.bat and rearrange it.  This is not a problem when
   launching wrendrdc.exe and wrib2rdc.exe because they are in the same
   directory as the DLL's they need.

Q: Can I use a Kernighan and Ritchie (K&R) C compiler?
A: Yes.  Just strip down the function prototypes in rdc.h and/or ri.h and you
   should be set.  Remember to cast your function arguments when necessary.