Untransformed display lists in a tile based rendering system
3-D rendering systems include a rasterization section that can fetch untransformed geometry, transform geometry and cache data for transformed geometry in a memory. As an example, the rasterization section can transform the geometry into screen space. The geometry can include one or more of static geometry and dynamic geometry. The rasterization section can query the cache for presence of data pertaining to a specific element or elements of geometry, and use that data from the cache, if present, and otherwise perform the transformation again, for actions such as hidden surface removal. The rasterization section can receive, from a geometry processing section, tiled geometry lists and perform the hidden surface removal for pixels within respective tiles to which those lists pertain.
1. A 3-D rendering system comprising a rasterization portion, the rasterization portion comprising:
a fetch unit, operable to retrieve untransformed 3-D position data for at least one element of static geometry appearing in a tile object list for a tile of pixels being processed;
a transform unit, operable to receive the untransformed 3-D position data and transform the 3-D position data into 2-D screen space coordinates for the at least one element of static geometry;
a hidden surface removal unit configured to receive the 2-D screen space coordinates for the at least one element of static geometry from the transform unit and operable to perform hidden surface removal for one or more pixels in the tile of pixels; and
a shading unit operable to shade a visible surface for the one or more pixels in the tile.
2. The 3-D rendering system of claim 1 , wherein the shading unit is operable to use parameters produced during geometry processing for shading dynamic geometry and parameters produced within the rasterization portion for shading static geometry.
3. The 3-D rendering system of claim 1 , further comprising a non-transitory memory storing 3-D position data and texturing and lighting parameter data for elements of static and dynamic geometry, and the rasterization portion is operable to retrieve the untransformed 3-D position information from the non-transitory memory.
4. The 3-D rendering system of claim 1 , further comprising:
one or more non-transitory memories storing 3-D position data and parameter data for elements of static and dynamic geometry; and
a geometry transformation unit operable to transform the 3-D position data for elements of both the dynamic geometry and the static geometry, to produce respective 2-D position data, in a 2-D screen space, for the transformed elements of geometry, and to perform attribute processing only for elements of the dynamic geometry.
5. The 3-D rendering system of claim 4 , further comprising:
a tiling unit operable to assemble the object tile lists based on the transformed elements of static and dynamic geometry, each object tile list comprising references to memory locations storing untransformed 3-D position and parameter data for the elements of static geometry.
6. The 3-D rendering system of claim 4 , further comprising:
a parameter buffer for receiving and storing transformed parameters for elements of dynamic geometry, the parameter buffer operable to be read by the rasterization portion.
7. The 3-D rendering system of claim 6 , further comprising a cull unit operable to receive transformed position information for dynamic geometry from the geometry transformation unit and to cull elements of geometry determined not to be visible, wherein transformed parameters for culled elements of geometry are not stored in the parameter buffer.
8. The 3-D rendering system of claim 4 , wherein the geometry transformation unit and the transform unit of the rasterization portion are implemented by a unitary geometry transform unit.
9. The 3-D rendering system of claim 1 , wherein the fetch unit is operable to attempt to fetch transformed parameters of the static geometry, corresponding to the untransformed parameters, from a cache before retrieving the untransformed parameters again.
10. The 3-D rendering system of claim 9 , wherein the fetch unit is operable to update the cache with transformed parameters for static geometry.
11. The 3-D rendering system of claim 1 , wherein the transform unit of the rasterization portion is implemented by a programmable unit, and the programmable unit further implements a transform unit within a geometry processing portion of the 3-D rendering system.
12. The 3-D rendering system of claim 1 , the fetch unit being further operable to obtain, from the tile object list for the tile of pixels being processed, a reference, for each element of static geometry appearing in the tile object list, to untransformed 3-D position data for that element of static geometry.
13. The 3-D rendering system of claim 1 , wherein dynamic geometry may be updated during a rendering.
14. The 3-D rendering system of claim 1 , wherein the 3-D rendering system is a tile-based 3-D rendering system.
15. The 3-D rendering system of claim 1 , the fetch unit being operable to retrieve untransformed 3-D position data for each element of static geometry appearing in a tile object list for a tile of pixels being processed.
16. The 3-D rendering system of claim 1 , the hidden surface removal unit being operable to perform hidden surface removal for each pixel in the tile of pixels.
17. The 3-D rendering system of claim 1 , the shading unit being operable to shade a visible surface for each pixel in the tile.