Rendering an image can be a very time consuming process, since it requires an enormous number of calculations to mathematically trace the rays of light around your 3D design. The best available method for speeding it up is to avoid calculations which are not really necessary. This chapter explains how program settings and the characteristics of your design will affect these calculations and the overall rendering time. Note that the "Render -> Estimate Render Time..." menu item can give you an estimate of what the overall rendering time for the current design and settings.
Image Size
Each pixel in a rendered image requires an individual "ray-tracing" calculation to determine what color it should be. All else being equal, the rendering time will always be proportional to the number of pixels in the image. Thus, it makes sense to let the image be as small as practical for what you are trying to accomplish. If you are just checking lighting, shadows, or intersections, a quarter or half screen image is often big enough. Remember that a half screen image contains one-forth as many pixels as a full screen image, so it will render four times as fast. So, if the image doesn't need to be big, don't make it big. You can also save a lot of time by only rendering small rectangles in the eye view window. This is often the best method of making sure that the final full size rendering will be what you want.
The Number Of Objects
An image which contains many objects will take longer to render than an image which contains only a few, especially if reflection, refraction, or shadow calculations are turned on. For example, with these features off, twice as many objects might take twice as long to render. However, if reflections, refractions, adn shadows are turned on, then the overall rendering time will increase more dramatically with the number of objects. For example, twice as many objects might take four times as long to render.
The Number Of Light Source Objects & Shadows
The existence of light source objects requires that RenderBoy calculate shadows and spectral reflections. This, more than anything else, can greatly increase the rendering time, especially as the total number of light sources increase.
For example, the addition of each light source object can easily increase the rendering time by fifty percent or more. Turning off these calculations in the "Render -> Render Settings" dialog box can greatly reduce the rendering time. This is useful when you are rendering a test image (which contains light source objects), but you do not care to see spectral reflections or shadows. I recommend not using more than two or three light source objects. More than that usually doesn't improve the image much, it just makes it take a really long time to render.
Note that light sources which do not generate shadows (described in the Modify Object Behavior" section of the "Object Manipulation" chapter) will not increase the rendering time significantly. Likewise, setting regular objects to not cast shadows will also decrease the rendering time, since unecessary shadow calculations can be avoided. In short, the fewer objects and lights which can generate shadows, the faster the rendering will be.
Reflective And Refractive Objects
Objects in your design which reflect or refract light will also greatly increase the rendering time. This is especially true as the total number of objects increases. This is because the light which hits these objects will continue traveling, and the ray-tracing calculations continue until the light stops. Turning off these calculations in the "Render -> Render Settings" dialog box will speed up the rendering process. This is a wise thing to do if you are testing lighting, object intersections, or other aspects of an image which do not depend on reflections or refractions.
Sharing the Processor
All Mac applications must cooperate with each other by sharing the central processing unit (CPU), and this includes RenderBoy. You can use the "Rendering In Progress -> CPU Sharing" menu to control which programs get more of the CPU. If other applications get more of the CPU, they will be more responsive, but your rendering times may increase a bit. If RenderBoy gets more of the CPU (the default), then RenderBoy will render as quickly as possible, but other applications will behave a bit sluggish. Determine your needs and adjust it accordingly.
