Tile Based Graphics Rendering

• US 20080259076A1
• Filed: 05/10/2005
• Published: 10/23/2008
• Est. Priority Date: 05/24/2004
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Inventors: Meinds, Kornelis
• Granted Patent: US 8,194,071 B2
• Time in Patent Office: Days
• US Class Current: 345/423
• CPC Class Codes: G06T 11/40 Filling a planar surface by adding surface attributes, e.g. colour or texture
• CPC Class Codes: G06T 15/005 General purpose rendering architectures
• CPC Class Codes: G06T 17/20 Finite element generation, e.g. wire-frame surface description, tesselation

Abstract

A graphics system for tile-by-tile converting of vertex data into output images for displaying on a screen. The vertex data represents objects by a set of polygons and comprises 3D space coordinates for each vertex (q1,q2, . . . ,q12) in the image. A polygon is constituted of at least three vertices (q1,q2, . . . ,q12). The system comprises a tile processor, for subdividing the image into a plurality of tiles (t21,22,t23) and for determining polygon strips (q1-q12), comprising a sequence of polygons. The tile processor is also operative to determine sub-strips (q3-q10) for each polygon strip (q1-q12). Each sub-strip (q3-q10) comprises those polygons of the polygon strip (q1-q12) which at least partly overlap a single one of the tiles (t21,22,t23). For processing a tile (t21,22,t23), only the sub-strips (q3-q10), i.e. the polygons covering that tile (t21,22,t23), have to be processed.

Claims

1. A graphics system for tile by tile converting of vertex data into output images for displaying on a screen the vertex data representing objects by a set of polygons, a polygon being constituted of at least three vertices the system comprising:

an input for receiving the vertex data, the vertex data at least comprising 3D space coordinates for each vertex in the image,

a tile processor for

subdividing the image into a plurality of tiles

determining polygon strips each polygon strip comprising a sequence of at least one polygon, each succeeding polygon of a polygon strip sharing a side with its preceding polygon, and

determining sub-strips for each polygon strip each sub-strip comprising those polygons of the polygon strip which at least partly overlap a single one of the tiles and associating that tile with the overlapping sub-strips,

a polygon-tile database comprising a display list for each tile the display list comprising a respective identification of each one of the sub-strips associated with the tile and

an output for enabling rendering of the images for display on the screen.

2. A graphics system as claimed in claim 1, wherein the identification for each one of the sub-strips associated with the tile comprises a reference to a first vertex of the sub-strip.

3. A graphics system as claimed in claim 2, wherein the identification for each one of the sub-strips associated with the tile comprises a reference to a last vertex of the sub-strip.

4. A graphics system as claimed in claim 2, wherein the identification for each one of the sub-strips associated with the tile comprises a number of vertices in the sub-strip.

5. A graphics system as claimed in claim 1, further comprising a vertex cache for caching the vertex data of the sub-strips associated with a tile.

6. A graphics system as claimed in claim 5, wherein the vertex cache is arranged for maintaining that vertex data that is to be used for a subsequent tile.

7. A graphics system as claimed in claim 5, wherein the vertex cache is arranged for pre-fetching vertex data that is to be used for a subsequent tile.

8. A method for tile by tile converting of vertex data into output images for displaying on a screen the vertex data representing objects by a set of polygons, a polygon being constituted of at least three vertices, the method comprising the steps of:

receiving the vertex data, the vertex data at least comprising 3D space coordinates for each vertex in the image;

subdividing the image into a plurality of tiles

determining polygon strips each polygon strip comprising a sequence of at least one polygon, each succeeding polygon of a polygon strip sharing a side with its preceding polygon;

for each polygon strip determining sub-strips, each sub-strip comprising those polygons of the polygon strip which at least partly overlap a single one of the tiles and associating that tile with the overlapping sub-strips;

filling a polygon-tile database comprising a display list for each tile each display list comprising a respective identification of each one of the sub-strips associated with the tile and

enabling rendering of the images for display on the screen.

9. A computer program product for causing a processor to perform the method as claimed in claim 8.