ELSA GLoria-L, User Manual

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All About Graphics
ELSA GLoria-L, -L/MX, -XL, -XXL
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– In Gouraud shading, all the vertices of the polygons are assigned a color value.
The remaining pixel information for the polygon is interpolated. This method
gives a very gentle color transition, even with fewer polygons than are required
for flat shading.
– The Phong shading method additionally takes a normal vector of reflectivity into
consideration when interpolating. An even more realistic impression is gener-
ated by the representation of reflections and mirror images.
– Certain applications use ray tracing methods. This is a very computer-intensive
and time-consuming process in which each individual pixel and its reflection in
3D space is calculated.
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The frame buffer
The finished image will not be written to the frame buffer until this complex se-
quence of steps is completed. The frame buffer is made up of front and back buffer.
The back buffer acts as a buffer page, in which the next image to be displayed is
built up. This prevents the process of image drawing being visible. The duplicate
storage method is also known as double buffering.
Flipping: Display on the monitor
The content of the front buffer is displayed on the monitor. When the drawing process
in the back buffer is completed, this image is then passed to the front buffer in a process
known as flipping.
The next image will only ever be displayed once the image drawing process in the back
buffer is completed. This procedure should be repeated at least 20 times a second to give
a smooth representation of 3D scenarios. In this context, we speak of frames per second
(fops), a very important value for 3D applications. A cinema film runs at 24 fps.
3D Interfaces
Software interfaces, including 3D interfaces, are known as APIs (Application Program
Interface). The question is what are these interfaces used for, and how do they work.
In simple terms: They make developers' work easier. The methods by which the various
interfaces function, are comparable: In the past it was necessary to address the various
hardware components directly in programming if you wanted to exploit their capabilities
to the full. The APIs are a kind of translator operating between the hardware and the
software.
The specification of standard definitions was the precondition for the proper function of
these translation routines. These definitions are implemented by the hardware manufac-
turers during development and optimized for the hardware concerned. Developers can
implement complex procedures relatively easily by using these definitions. They can use