Layer combination in a surface composition system

• US 8,629,886 B2
• Filed: 12/07/2010
• Issued: 01/14/2014
• Est. Priority Date: 12/07/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Michail, Ashraf, Liu, Alan
• Primary Examiner(s): Wu, Xiao M.
• Assistant Examiner(s): BUTTRAM, ALAN T
• Application Number:
  US12/961,501
• Publication Number:
  US 20120139918A1
• Time in Patent Office: 1,134 Days
• Field of Search: 345/419, 345/422, 345/629, 345/421
• US Class Current: 345/629
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing
• CPC Class Codes: G06T 2210/62 Semi-transparency

Abstract

A system and method for processing and rendering multiple layers of a two-dimensional scene. A system provides a mechanism to determine a number of scene surfaces and a mapping between scene layers and scene surfaces. The mechanisms may include combining and aggregating areas of layers to create one opaque surface, aggregating non-overlapping semi-transparent opaque areas of layers, or creating surfaces from overlapping semi-transparent surfaces. Moving objects are accommodated, so that layers below a moving object may be rendered properly in frames where the moving object is above the layer and frames where the moving object is not above the layer, for each pixel.

Claims

1. A computer-based method of rendering a two-dimensional graphic scene, the method comprising:

a) receiving a scene graph including a first static layer having a corresponding depth value, a second static layer having a corresponding depth value, and a moving layer, the moving layer having a depth value between respective depth values of the first static layer and the second static layers;

each of the first static layer and the second layer containing a corresponding vector element;

b) determining a first area of pixels in the first static layer and a second area of pixels in the second static layer, the pixels of the first area having different pixel addresses from the pixels of the second area;

c) creating a first surface that includes the first area and the second area, the first surface comprising a depth value corresponding to each pixel of the first area and the second area;

d) creating a second surface that includes a moving area of the moving layer; and

e) providing the first surface and the second surface to a graphics processing unit for composition of the first surface and the second surface based on the depth values;

f) rasterizing at least one vector element of the second static layer prior to providing the first surface and the second surface to the graphics processing unit for composition, and not rasterizing at least one other vector element of the second layer.

2. The computer-based method of claim 1, further comprising determining the first area to be an area containing topmost opaque pixels at the pixel addresses of the first area, and determining the second area to be an area containing topmost opaque pixels at the pixel addresses of the second area.

3. The computer-based method of claim 1, wherein the pixels of the first area are semi-transparent pixels and the pixels of the second area are semi-transparent pixels.

4. The computer-based method of claim 1, further comprising determining the first area to be an area containing semi-transparent pixels of the first layer that do not overlap semi-transparent pixels of the second layer;

and creating a third surface that includes semi-transparent pixels of the first layer that overlap semi-transparent pixels of the second layer.

5. The computer-based method of claim 1, further comprising:

a) creating a moving surface derived from the moving layer, each pixel of the moving surface having a corresponding depth value;

b) providing the moving surface to the graphics processing unit for composition with the first surface and the second surface;

c) storing the first surface and the second surface in a surface cache; and

d) for each frame of the two-dimensional graphic scene, providing the first surface and the second surface to the graphics processing unit from the cache.

6. The computer-based method of claim 1, further comprising, for each frame of the graphic scene, positioning the second surface relative to the first surface.

7. The computer-based method of claim 1, further comprising creating a third surface that includes pixels corresponding to an overlapping third area of the first static layer and the second static layer, the third surface comprising, for each pixel of the overlapping third area, a depth value of a corresponding pixel of the second static layer.

8. The computer-based method of claim 1, further comprising creating a third surface that includes pixels corresponding to an overlapping third area of the first static layer and the second static layer, the third surface comprising, for each pixel of the overlapping third area, a depth value of a corresponding pixel of the second static layer, the first surface further comprising, for each pixel of the overlapping third area, a depth value of a corresponding pixel of the first static layer.

9. The computer-based method of claim 1, the scene graph including a number of static layers, including the first static layer and the second static layer, the method further comprising creating a number of static surfaces from the static layers, the number of static surfaces being greater than one and less than the number of static layers, the number of static surfaces based on a number of semi-transparent layers included in the number of static layers, a number of moving layers, and a depth of each moving layer.

10. A computer-readable storage memory comprising computer program instructions for rendering a two-dimensional graphic scene, the program instructions executable by one or more processors to perform actions including:

a) receiving at least one moving layer having a corresponding depth value;

b) receiving a plurality of static layers, each static layer having a corresponding depth value, each static layer separated from other static layers by one or more of the at least one moving layers, each static layer containing at least one vector element;

c) determining a set of topmost opaque pixels, including pixels from at least two of the static layers;

d) creating an opaque surface including the set of topmost opaque pixels, the opaque surface having a depth buffer that indicates a z-order for each pixel, including at least two different z-order values;

e) creating one or more moving surfaces derived from the at least one moving layer, the moving surface having a depth buffer that indicates a z-order for each pixel; and

f) providing the opaque surface and the one or more moving surfaces to a compositor for composition of the opaque surface and the one or more moving surfaces;

wherein creating the opaque surface comprises rasterizing at least one vector element from a static layer of the plurality of static layers and determining pixels from the static layer of the plurality of static layers to exclude from rasterization; and

wherein rasterizing the at least one vector element is performed prior to providing the opaque surface and the one or more moving surfaces to the compositor.

11. The computer-readable storage memory of claim 10, the actions further including:

a) creating a semi-transparent surface by selectively selecting semi-transparent pixels from the plurality of static layers based on whether each pixel overlaps another semi-transparent pixel with a moving layer in between the pixel and the other semi-transparent pixel.

12. The computer-readable storage memory of claim 10 the actions further including creating a first static surface including semi-transparent pixels that each overlap at least one other semi-transparent pixel, and creating a second static surface including semi\-transparent pixels that do not overlap at least one other semi-transparent pixels.

13. A computer-based system for rendering a two-dimensional graphic scene having a plurality of static layers and at least one moving layer, each of the plurality of static layers containing at least one vector element and separated from other static layers of the plurality of static layers by at least one moving layer, the system comprising:

a) a rasterizer configured to perform actions including;

i) receiving a scene graph representing the graphic scene;

ii) determining at least two areas of respective static layers of the plurality of static layers to be aggregated into one static surface;

iii) after determining the at least two areas, rasterizing the at least two areas to create the one static surface, each pixel of the one static surface having a corresponding depth level; and

iv) creating at least one moving surface based on the at least one moving layer, each pixel of the at least one moving surface having a corresponding depth level; and

b) a processor configured to compose a frame of the graphic scene by composing the one static surface and the moving surface by employing the depth level of each pixel of the at least one moving surface and the depth level of each pixel of the one static surface;

wherein the rasterizer actions further include selectively rasterizing each pixel of a vector element of at least one static layer of the plurality of static layers prior to providing the static surface and the moving surface to the processor, based on whether the pixel is obscured by an opaque element of another static layer of the plurality of static layers.

14. The computer-based system of claim 13, determining the at least two areas comprising:

a) determining whether semi-transparent pixels of each static layer overlap semi-transparent pixels of other static layers; and

b) determining the at least two areas based on the determination of overlapping semi-transparent pixels.

15. The computer-based system of claim 13, determining the at least two areas comprising:

a) determining whether semi-transparent pixels of each static layer overlap semi-transparent pixels of other static layers; and

b) determining the at least two areas to exclude semi-transparent pixels of each static layer that overlap semi-transparent pixels of other static layers.

16. The computer-based system of claim 13, determining the at least two areas comprising:

a) determining whether semi-transparent pixels of each static layer overlap semi-transparent pixels of other static layers; and

b) determining the at least two areas to include semi-transparent pixels of each static layer that overlap semi-transparent pixels of other static layers.

17. The computer-based system of claim 13, the rasterizer comprising means for determining static surfaces that include pixels from each of two or more static layers based on an opacity level of each pixel and a relationship of pixels having a common pixel address.

18. The computer-based system of claim 13, further comprising means for storing a depth value of each pixel in each surface.