MULTILEVEL DISPLAY CONTROL LIST IN TILE BASED 3D COMPUTER GRAPHICS SYSTEM

• US 20110292032A1
• Filed: 12/21/2009
• Published: 12/01/2011
• Est. Priority Date: 12/19/2008
• Status: Active Grant

• Current Assignee: Imagination Technologies Limited (Imagination Technologies Group Ltd.)
• Original Assignee: Imagination Technologies Limited (Imagination Technologies Group Ltd.)
• Inventors: Yang, Xile
• Granted Patent: US 9,336,623 B2
• Time in Patent Office: Days
• US Class Current: 345/419
• 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

Abstract

A method and apparatus are provided for rendering a 3 dimensional computer graphics image. The image is divided into plurality of rectangular tiles which are arranged in a multi level structure comprising a plurality of levels of progressively larger groupings of tiles. Image data is divided into a plurality of primitive blocks and these are assigned to groupings of tiles within the multi level structure in dependence on the groupings each one intersects. Control stream data is derived for rendering the image and this comprises references to primitive blocks for each grouping of tiles within each level of the multi level structure, the references corresponding to the primitive blocks assigned to each grouping and control stream data is used to render the primitive data into tiles within the groupings of tiles for display. This is done such that for primitive blocks which intersect a plurality of tiles within a grouping, control stream data is written for the grouping of tiles rather than for each tile within the grouping.

Claims

1. A method for rendering a 3 dimensional computer graphics image comprising the steps of:

subdividing the image into a plurality of rectangular tiles;

arranging the tiles in a multi level structure comprising a plurality of levels of progressively larger groupings of tiles;

dividing image data to be rendered into a plurality of primitive blocks containing image data required to render the image;

assigning each primitive block to a grouping of tiles within the multi level structure in dependence on the grouping of tiles it intersects, such that each primitive block is assigned to a grouping in one of the levels in the multi level structure;

deriving control stream data for rendering the image, the control stream data comprising references to primitive blocks for each grouping of tiles within each level of the multi level structure corresponding to the primitive blocks assigned to each grouping; and

using the control stream data to render primitive data into tiles within the groupings of tiles for display.

2. A method according to claim 1 in which the control stream data includes a Tile Block Control Word and including the step of determining for the status of the Tile Block Control Word whether a primitive block is to be processed in rendering respective tile block.

3. A method according to claim 2 in which the control stream data includes a Tile Block Control Format Word, which is used after each primitive block determined to be processed for a tile block, to determine whether the primitive block is to be processed for a tile currently being processed.

4. A method according to claim 3 in which the control stream data includes a Full Primitive Mask Flag Present bit to determine whether any full primitive masks are present in the control stream data, and the full primitive masks are used to get a bit for each tile in a tile block which determines whether all primitives in a primitive block are visible in each respective tile.

5. A method according to claim 4 in which the control stream data comprises a Primitive Mask Format Word which is used to determine which tiles in a tile block have full primitives masks when the Full Primitive Mask Flag Present bit is not reset.

6. Apparatus for rendering 3 dimensional computer graphics image comprising:

means for subdividing the image into a plurality of rectangular tiles;

means for arranging the tiles in a multi level structure comprising a plurality of levels of progressively larger groupings of tiles;

means for dividing image data to be rendered into a plurality of primitive blocks containing image data required to render the image;

means for assigning each primitive block to a grouping of tiles within the multi level structure independence on the grouping of tiles in intersects, such that each primitive block is assigned to a grouping in one of the levels in the multi level structure;

means for deriving control stream data for rendering the image, the control stream data comprising references to primitive blocks for grouping of tiles within each level of the multi level structure corresponding to the primitive blocks assigned to each grouping; and

means for using the control stream data to render primitive data into tiles within the groupings of tiles for display.

7. An apparatus according to claim 6 in which the control stream data includes a Tile Block Control Word and the system includes the means for determining from the status of the Tile Block Control Word whether a primitive block is to be processed in rendering a respective tile block.

8. A system according to claim 7 which the control stream data includes a Tile Block Control Format Word and means for using the Tile Block Control Format Word to determine for each primitive determined to be required to be processed to a tile block to determine whether the primitive block is to be processed for a tile currently being processed within the tile block.

9. A system according to claim 8 in which the control stream data includes a Full Primitive Mask Flag Present bit and including the step of determining whether any Full Primitive Mask bits are present in the control stream data from the Full Primitive Mask Flag Present bit and means for setting Full Primitive Masks bits for each the in a tile block to determine whether full primitives in a primitive block are visible in each respective tile.

10. A system according to claim 9 in which the control stream data comprises a Primitive Mask Format Word and including means to determine from the Primitive Mask Format Word which tiles in a tile block have full primitive masks when the Full Primitive Mask Flag Present bit is not set.