Intergraph RealiZm Graphics V25, Руководство пользователя по оборудованию

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Request Handler
The request handler monitors the data output of the graphics FIFO. When data arrives, the
request handler analyzes it and writes it to an appropriate processing block. The request
handler routes vertex data for triangles and lines to the slope calculation block.
Drawing requests (other than vertex data for triangles and lines) such as blits, fills, and bit
expands, bypass the slope calculation and span generation blocks. The request handler routes
this data directly to the pixel interpolation block.
Slope Calculation
The slope calculation block performs the slope calculation part of the rasterization process for
triangles and lines. Floating-point math ensures the accuracy of triangle edges.
The slope calculation block calculates color derivatives, depth derivatives, and edge slopes. It
also adjusts the vertex data to a pixel center for the topmost vertex. The slope calculation
block converts all data to a fixed-point format and routes it to the span generation block.
Span Generation
The span generation block performs the span calculation part of the rasterization process for
triangles and lines. The span generation block determines the leftmost x and y coordinates for
each scanline in a triangle. It also calculates the initial color and depth value for each
scanline, and routes the data to the pixel interpolation block.
Pixel Interpolation
The pixel interpolation block is common for all graphics drawing requests. For triangle
meshes, the pixel interpolation block expands the data from the span generation block to pixel
data by successively adding the x-derivative value to the initial color and depth values (z) for
each span.
The pixel interpolation block also sends the (x, y) address and pixel data to the frame buffer
over the IZ bus. The IZ bus is a 64-bit bus with a pixel span protocol to facilitate high data
throughput. This protocol allows burst transfers of pixel data to occur between the
rasterization accelerator and the frame buffer. The maximum burst size is 4096 pixels.
Texture Processor
A Texture Processor is contained in the Graphics Engine/Texture Processor ASIC on the Z13,
Z25, and V25, and as separate ASICs on the Z10. Texturing is the process of applying texture
patterns to the surface of a 3D graphics object to enhance the visual realism of the object, or
of an entire scene.