Abstract: A computer graphics system may comprise a graphics processor, a sample buffer, and a sample-to-pixel calculation unit. The graphics processor renders samples into the sample buffer in response to received graphics data. The sample-to-pixel calculation unit generates a plurality of output pixels by filtering the rendered samples based on a filter function. The pixels may be computed by generating a weighted sum of sample values (e.g. red sample values) for samples falling within the filter support. The coefficients used in the weighted sum may be added to form a normalization factor. One weighted sum of sample values may be computed per pixel attribute such as red, green, blue and alpha. The normalization factor may be computed in parallel with one or more of the weighted sums. Normalized pixel values may be obtained by dividing the weighted-sums by the normalization factor.

Abstract: A method, apparatus, and system are described for rasterizing a triangle. Pixel parameter values are interpolated by adding or subtracting a vertical delta or by adding or subtracting a horizontal delta within a 4×4 tile of 16 pixels.

Abstract: A computer graphics system that utilizes a super-sampled sample buffer and a sample-to-pixel calculation unit for refreshing the display. The graphics system may have a graphics processor, a super-sampled sample buffer, and a sample-to-pixel calculation unit. The graphics processor renders samples into the sample buffer and may utilize a window ID that specifies attributes of pixels on a per object basis. The window ID may specify one or more of a sample mode, filter type, color attributes, or source attributes. The sample mode may include single sample per pixel mode and multiple samples per pixel mode. The graphics system may be further operable to generate a single sample per pixel for certain windows of the screen in order to provide backwards compatibility with legacy systems.

Abstract: A graphics system that is configured to utilize a sample buffer and a plurality of parallel sample-to-pixel calculation units, wherein the sample-pixel calculation units are configured to access different portions of the sample buffer in parallel. The graphics system may include a graphics processor, a sample buffer, and a plurality of sample-to-pixel calculation units. The graphics processor is configured to receive a set of three-dimensional graphics data and render a plurality of samples based on the graphics data. The sample buffer is configured to store the plurality of samples for the sample-to-pixel calculation units, which are configured to receive and filter samples from the sample buffer to create output pixels. Each of the sample-to-pixel calculation units are configured to generate pixels corresponding to a different region of the image. The region may be a vertical or horizontal stripe of the image, or a rectangular portion of the image.

Abstract: A method and computer graphics system capable of implementing multiple pipelines for the parallel processing of graphics data. For certain data, a requirement may exist that the data be processed in order. The graphics system may use a set of tokens to reliably switch between ordered and unordered data modes. Furthermore, the graphics system may be capable of super-sampling and performing real-time convolution. In one embodiment, the computer graphics system may comprise a graphics processor, a sample buffer, and a sample-to-pixel calculation unit. The graphics processor may be configured to receive graphics data and to generate a plurality of samples for each of a plurality of frames. The sample buffer, which is coupled to the graphics processor, may be configured to store the samples. The sample-to-pixel calculation unit is programmable to generate a plurality of output pixels by filtering the rendered samples using a filter.

Abstract: A method and computer graphics system for clip testing using clip bits stored in a general-purpose register for each vertex of a geometric primitive. In one embodiment, a rendering unit or other processor sets bits in a clip bits register for each vertex of a geometric primitive. Each bit indicates whether the vertex is inside or outside of a clipping boundary with respect to a particular clipping plane. A frame buffer controller or other graphics processor performs clip testing on the entire geometric primitive by performing Boolean operations on the clip bits. The frame buffer controller may trivially accept or trivially reject the primitive based on the clip testing. If the primitive cannot be trivially rejected or trivially accepted, then the frame buffer controller sends an interrupt to the rendering unit. The rendering unit reads an exception register to determine that the reason for the interrupt is the need to clip the primitive.

Abstract: A sample-to-pixel calculation unit in a graphics system may comprise an adder tree. The adder tree includes a plurality of adder cells coupled in a tree configuration. Input values are presented to a first layer of adder cells. Each input value may have two associated control signals: a data valid signal and a winner-take all signal. The final output of the adder tree equals (a) a sum of those input values whose data valid signals are asserted provided that none of the winner-take all signals are asserted, or (b) a selected one of the input values if one of the winner-take-all bits is asserted. The selected input value is the one whose winner-take-all bit is set. The adder tree may be used to perform sums of weighted sample attributes and/or sums of coefficients values as part of pixel value computations.

Abstract: A dithering system comprising a dithering unit, a storage medium, and an averaging unit. The dithering unit is configured to receive a set of data values, to add dither values to the data values, and to truncate the resultant addition values to L-bit truncated values. The storage medium is configured to store the L-bit truncated values. The averaging unit is configured to read the L-bit truncated values from the storage medium, and to compute an average value using at least a subset of the L-bit truncated values. The dither values may have an average value of approximately one-half. The dither values may approximate a uniform distribution of numbers between −A+½ and A+½, wherein A is greater than or equal to one. Alternatively, the dithering unit may receive a temporal stream of data values, and the average unit may perform a temporal average (e.g. an FIR filter). The dithering system may be incorporated in a graphics system.

Abstract: A graphics system and method for displaying lines on a display device. The system may comprise a sample buffer, a rendering unit and a sample-to-pixel calculation unit. The rendering unit may (a) generate a plurality of sample positions in a two-dimensional space, (b) determine a sample normal distance for each of the sample positions with respect to a line defined by the line-draw command, (c) assign sample values to the sample positions based on the sample normal distance of each of the sample positions, and (d) store the sample values in the sample buffer. The sample-to-pixel calculation unit may read sample values from the sample buffer, filter them to determine a pixel value, and transmit the pixel value to the display device. The rendering unit may render the line sample values with a narrower width to pre-compensate for the line-expanding effect of the filtering performed by the sample-to-pixel calculation unit.

Abstract: A computer graphics system may comprise a graphics processor, a sample buffer, and a sample-to-pixel calculation unit. The graphics processor renders samples into the sample buffer in response to received graphics data. The sample-to-pixel calculation unit generates a plurality of output pixels by filtering the rendered samples based on a filter function. The pixels may be computed by generating a weighted sum of sample values (e.g. red sample values) for samples falling within the filter support. The coefficients used in the weighted sum may be added to form a normalization factor. One weighted sum of sample values may be computed per pixel attribute such as red, green, blue and alpha. The normalization factor may be computed in parallel with one or more of the weighted sums. Normalized pixel values may be obtained by dividing the weighted-sums by the normalization factor.

Abstract: A computer graphics system that utilizes a super-sampled sample buffer and a sample-to-pixel calculation unit for refreshing the display. The graphics system may have a graphics processor, a super-sampled sample buffer, and a sample-to-pixel calculation unit. The graphics processor renders samples into the sample buffer and may utilize a window ID that specifies attributes of pixels on a per object basis. The window ID may specify one or more of a sample mode, filter type, color attributes, or source attributes. The sample mode may include single sample per pixel mode and multiple samples per pixel mode. The graphics system may be further operable to generate a single sample per pixel for certain windows of the screen in order to provide backwards compatibility with legacy systems.

Abstract: A computer graphics system that utilizes a super-sampled sample buffer and a sample-to-pixel calculation unit for refreshing the display. The graphics system may have a graphics processor, a super-sampled sample buffer, and a sample-to-pixel calculation unit. The graphics processor renders samples into the sample buffer at computed positions or locations in the sample buffer. The graphics system may utilize a window ID that specifies attributes of pixels on a per object basis. The window ID may specify one or more of a sample mode, filter type, color attributes, or source attributes. The sample mode may include single sample per pixel mode and multiple samples per pixel mode. In implementing a single sample per pixel mode, the graphics system may be further operable to generate a single sample per pixel for certain windows of the screen in order to, for example, provide backwards compatibility with legacy systems with no multi-sampling support.

Abstract: A rapid method for calculating a local eye vector in a fixed point lighting unit. For a given triangle primitive which is to be projected into a given viewport in screen space coordinates, the local eye vector corresponds to a given eye position and a first vertex of the given triangle primitive. (A different local eye vector is calculated for each vertex of the given triangle primitive). The method first comprises generating a view vector matrix which corresponds to the given eye position and corner coordinates of the given viewport, where the corner coordinates are expressed in screen space coordinates. The view vector matrix is usable to map screen space coordinates to an eye vector space which corresponds to the given viewport. The method next includes receiving a first set of coordinates (in screen space) which correspond to the first vertex. The first set of coordinates are then scaled to a numeric range which is representable by the fixed point lighting unit.

Abstract: A 3-D graphics accelerator for performing lighting operations using operands within a given fixed point numeric range. The 3-D graphics accelerator includes a first computational unit which is configured to compute a value of an attenuation factor usable for performing said lighting operation for local lights. The attenuation factor is represented in floating point format. The first computational unit is also configured to represent the attenuation factor in an intermediate format including a first intermediate value (a scaled attenuation factor value within the given fixed point numeric range), and a second intermediate value (a shift count usable to convert the scaled attenuation factor value back to the original attenuation factor value). The 3-D graphics accelerator further includes a lighting unit coupled to said first computational unit. The first computational unit is further configured to convey the intermediate representation of the attenuation factor to the lighting unit.

Abstract: A rapid method for calculating a local eye vector in a fixed point lighting unit. For a given triangle primitive which is to be projected into a given viewport in screen space coordinates, the local eye vector corresponds to a given eye position and a first vertex of the given triangle primitive. (A different local eye vector is calculated for each vertex of the given triangle primitive). The method first comprises generating a view vector matrix which corresponds to the given eye position and corner coordinates of the given viewport, where the corner coordinates are expressed in screen space coordinates. The view vector matrix is usable to map screen space coordinates to an eye vector space which corresponds to the given viewport. The method next includes receiving a first set of coordinates (in screen space) which correspond to the first vertex. The first set of coordinates are then scaled to a numeric range which is representable by the fixed point lighting unit.

Abstract: A computer system which exhibits increased performance for stereo viewing. The computer system includes a display screen, a bus for transferring data, a memory coupled to the bus for storing geometric primitives and left and right view transformation matrices. Furthermore, the computer system includes a processor coupled to the bus, wherein the processor is configured to enable stereo mode and to execute an application for rendering objects on the display screen in the stereo mode. The computer system also includes a graphics accelerator coupled to the bus. The graphics accelerator includes a buffer for storing a received geometric primitive to be rendered in stereo mode, as well as memory for storing the left and right view transformation matrices. The graphics accelerator also includes a transformation unit which is configured to generate a first transformed geometric primitive in response to the received geometric primitive and the left view transformation matrices.

Abstract: A lighting unit which exhibits improved handling of incoming color values corresponding to a polygon. The lighting unit includes an input buffer for storing a plurality of color values, a mode register including a color mode field specifying whether the plurality of color values corresponds to the front or back side of the polygon. Furthermore, the lighting unit includes a register file for storing color information. The register file includes a first and second plurality of registers for storing front and back side color information, respectively. Still further, the lighting unit includes input/output logic configured to perform a transfer color instruction, which first comprises accessing the mode register to obtain a value of the color mode field, and then transferring the plurality of color values from the input buffer to one or more registers within the register file.