45 results about "Stencil buffer" patented technology

A method for real-time shadow rendering in a 3-D graphics scene uses an inverted z-test to mark a shadow area in a stencil buffer. Front and back facing shadow volume polygons are rendered subsequent to rendering the scene and corresponding stencil buffer entries are incremented for pixels viewing the back facing polygon when the new z-test is passed and decremented for pixels viewing the front facing polygons when the new z-test is passed. The new z-test is passed for pixels having depth (z) values greater than the corresponding depth value stored z-buffer.

A method, computer program product and system for rendering soft shadows in an image or frame representing a 3D scene, comprising the steps, from a light's point of view, of detecting and creating a list of edges casting shadows, a list of soft shadow edges and a list of shadow volumes polygons; rendering said soft shadow edges into one or more sides of a cubemap, rendering said shadow volume polygons in combination with a stencil buffer to detect full shadowed areas; from a viewer's point of view rendering said scene with said cubemap applied while performing a stencil test operation for preventing the scene to be drawn in shadowed areas, to produce a soft shadowed image.In addition, the system supports the re-use of the shadow volumes and cubemap information for more than one frame.

The computer graphics system is configured to generate a shadow effect with a stencil shadow volume method using a combination of compressed and uncompressed stencil buffers in coordination with compressed and uncompressed depth data buffers. An uncompressed stencil buffer is capable of storing stencil shadow volume data for each pixel and a compressed stencil buffer is capable of storing stencil shadow volume data for a group of pixels.

An ablation treatment planning and, optionally, guiding method usable for e.g. tumour tissue ablation with a cryoablation needle which cools down an adjacent tumour tissue to thereby generate an ablation volume is proposed. In order to be able to plan an ablation treatment, a 3D image data set of a region of interest may be acquired by e.g. X-ray imaging using e.g. a C-arm system. Then, 3D model data of the ablation volume are introduced into the 3D image data set for example by tagging image pixels using a stencil buffer and possibly by culling specific inside areas and / or outside areas of the ablation volume. Finally, a 2D image to be visualized to a physician and comprising a projection of the region of interest and the ablation volume is drawn wherein an MPR (multi planar reformatting) plane in which the 2D image is drawn is used as a clipping plane. With such graphical approach, an ablation volume having any arbitrary shape such as for example an ellipsoid shape may be visualized within a 3D image space by drawing 2D images in any desired MPR plane such that also oblique orientations of the ablation volume can be represented. In a subsequent guiding procedure, an ablation needle may be guided to a location and in an orientation as previously planned.

One embodiment of the present invention sets forth a technique for rendering paths by first generating a stencil buffer indicating pixels of the path that should be covered and then covering the path. The paths may be filled or stroked without tessellating the paths. Path rendering may be accelerated when a graphics processing unit or other processor that is configured to perform operations to generate the stencil buffer and cover the path to fill or stroke the path.

One embodiment of the present invention sets forth a technique for decomposing and filling cubic Bèzier segments of paths without tessellating the paths. Path rendering may be accelerated when a GPU or other processor is configured to perform the decomposition operations. Cubic Bèzier paths are classified and decomposed into simple cubic Bèzier path segments based on the classification. A stencil buffer is then generated that indicates pixels that are inside of the decomposed cubic Bèzier segments. The paths are then filled according to the stencil buffer to produce a filled path.

One embodiment of the present invention sets forth a technique for rendering anti-aliased paths by first generating an alpha buffer representing coverage data. To generate the alpha buffer, jittered versions of the rendered path are rendered and corresponding stencil buffers indicating sub-pixel samples of the path that should be covered are generated. After each stencil buffer is generated, the jittered path is rasterized to convert the sub-pixel coverage into coverage weights that are stored in the alpha component of a frame buffer. As each jittered path is rasterized, the coverage weights are accumulated. Finally, geometry representing the union of the jittered versions of the path is rendered to shade pixels based on the accumulated coverage weights. The anti-aliased rendered paths may be filled or stroked without tessellating the paths.

A method for rendering pixels for display includes generating stencil values on a per pixel basis for storage in stencil buffer memory; selecting a group of stencil values that represent a block of pixels; generating compressed stencil data associated with the group of stencil values; and performing stencil testing on a corresponding incoming block of pixels using the compressed stencil data.

An image rendering method is provided, comprising comparing a current image frame with a previous image frame to detect a dynamic change in an object in the image frames, with each image frame being defined by a scene graph and each object having an associated geometric bounding volume. If a dynamic change in an object is detected, the method comprises rendering the object's geometric bounding volume to a stencil buffer for each dynamically changed object, using a stencil value assigned to the current image frame. A stencil is then applied to determine areas in the frames having non-zero stencil values. The method further comprises clearing a color buffer with respect to the areas in the previous image frame that have been redrawn and with respect to areas in the current frame that need to be overdrawn, rendering the image frame to the color buffer using a stencil test, so that only the areas with non-zero stencil values are redrawn, and then removing the stencil values from a previous image frame from the stencil buffer.

An apparatus, method, and article of manufacture are configured to display a vector marker stroke. A stroked fill of vector splines and polygons having faces along the spline are created based on a user input marker stroke. A stencil buffer is created indicating the number of vector faces incident at each pixel. When the number indicates that a pixel has overlapping faces, a pixel shader (that determines an opacity value for the pixel in a mask) is executed as many times as the number. When the number indicates that a pixel has at least one face and is at a beginning or an ending of the stroke, the shader is executed to add to the opacity value. A blur shading operation is executed on each of the pixels. The stroked fill is rendered and a wet color is rendered, using the mask, on top of the stroked fill.

A DVD-ROM stores a plurality of shadow volume data corresponding to respective attitudes of an object which casts a shadow. A CPU sets a shadow volume corresponding to the attitude of the object by performing interpolation based on the shadow volume data as necessary. Based on the thus-set shadow volume, a GPU determines a shadow region using a stencil buffer. Based on the determined results, the GPU updates luminance information of each pixel stored in a color buffer. According to this configuration, when a game system uses the shadow volume to draw a shadow, it is possible to reduce the processing load caused by setting the shadow volume while drawing a more realistic shadow corresponding to the attitude of the object which casts the shadow.

One embodiment of the present invention sets forth a technique for improving path rendering on computer systems by efficiently representing and computing sub-pixel coverage for path objects. A stencil buffer is configured to store multiple stencil samples per pixel stored in an image buffer. The stencil samples undergo stencil testing to produce a set of Boolean values per pixel, which collectively define a geometric coverage percentage for the pixel. The coverage percentage is used to modulate a color value for the pixel. The modulated color value is then blended into the image buffer as an anti-aliased pixel. This technique advantageously enables efficient anti-aliasing for path rendering.

A method and apparatus for rendering a computer generated image using a stencil buffer is described. The method divides an arbitrary closed polygonal contour into first and higher level primitives, where first level primitives correspond to contiguous vertices in the arbitrary closed polygonal contour and higher level primitives correspond to the end vertices of consecutive primitives of the immediately preceding primitive level. The method reduces the level of overdraw when rendering the arbitrary polygonal contour using a stencil buffer compared to other image space methods. A method of producing the primitives in an interleaved order, with second and higher level primitives being produced before the final first level primitives of the contour, is described which improves cache hit rate by reusing more vertices between primitives as they are produced.

A raster operations (ROP) unit is configured to compress stencil values included in a stencil buffer. The ROP unit divides the stencil values into groups, subdivides each group into two halves, and selects an anchor value for each half. If the difference between each of the stencil values and the corresponding anchor lies within an offset range, and the difference between the two anchors lies within a delta range, then the group is compressible. For a compressible group, the ROP unit encodes the anchor value, offsets from anchors, and an anchor delta. This encoding enables the ROP unit to operate on the compressed group instead of the uncompressed stencil values, reducing the number of memory and computational operations associated with the stencil values. Consequently, the ROP unit reduces memory bandwidth use, reduces power consumption, and increases rendering rate compared to conventional ROP units that implement less flexible compression techniques.

Methods and apparatuses for effectively clearing stencil buffers at high speed using surrogate stencil buffer clearing. A hardware register tracks the number of surrogate clears of the stencil buffer since the last actual clear. Bits are reserved in each stencil register for storing the surrogate clear number that cleared other stencil registers the last time the stencil register held an assigned value. A comparison between the contents of the hardware register and the reserved bits in each stencil register determines if each stencil register should be assigned a cleared value. If the numbers do not match the stencil register is assigned a predetermined surrogate clear value. In some applications the number of reserved bits is fixed, while in other applications the number of reserved bits can be set, either by a designer or by software.

The computer graphics system is configured to generate a shadow effect with a stencil shadow volume method using a combination of compressed and uncompressed stencil buffers in coordination with compressed and uncompressed depth data buffers. An uncompressed stencil buffer is capable of storing stencil shadow volume data for each pixel and a compressed stencil buffer is capable of storing stencil shadow volume data for a group of pixels.

Hierarchical culling can be used during shadow generation by using a stencil buffer generated from a light view of the eye-view depth buffer. The stencil buffer indicates which regions visible from an eye-view are also visible from a light view. A pixel shader can determine if any object could cast a shadow by comparing a proxy geometry for the object with visible regions in the stencil buffer. If the proxy geometry does not cast any shadow on a visible region in the stencil buffer, then the object corresponding to the proxy geometry is excluded from a list of objects for which shadows are to be rendered.

One embodiment of the present invention sets forth a technique for decomposing and filling cubic Bèzier segments of paths without tessellating the paths. Path rendering may be accelerated when a GPU or other processor is configured to perform the decomposition operations. Cubic Bèzier paths are classified and decomposed into simple cubic Bèzier path segments based on the classification. A stencil buffer is then generated that indicates pixels that are inside of the decomposed cubic Bèzier segments. The paths are then filled according to the stencil buffer to produce a filled path.

One embodiment of the present invention sets forth a technique for rendering paths by first generating a stencil buffer indicating pixels of the path that should be covered and then covering the path. The paths may be filled or stroked without tessellating the paths. Path rendering may be accelerated when a graphics processing unit or other processor that is configured to perform operations to generate the stencil buffer and cover the path to fill or stroke the path. When the paths are rendered in a top-to-bottom (front-to-back) order, an opacity stencil may be generated and used to avoid determining path coverage and shading for pixels that are opaque.

One embodiment of the present invention sets forth a technique for rendering clipped paths by first generating clip stencil buffer state indicating pixels that are inside of the clip path. The clip stencil buffer state may also store an opacity value for each covered pixel to generate a mask that modulates the opacity of a draw path that is clipped. Clipped draw stencil buffer state is then generated indicating pixels of the draw path that should be covered based on the clip stencil buffer state and coverage of the draw path. The clipped draw path is then filled or stroked to produce the clipped draw path. The clip and draw paths may be filled or stroked without tessellating the paths. Path rendering may be accelerated when a GPU or other processor that is configured to perform operations to generate the clip stencil buffer state and the clipped draw stencil buffer state, and to fill or stroke the clipped draw path.

A method, system, and computer-readable storage medium are disclosed for rendering an artwork comprising a plurality of surfaces, wherein the plurality of surfaces comprises a plurality of semi-transparent surfaces unsorted in depth. An identifier of the nearest semi-transparent surface may be determined and stored in a stencil count of a stencil buffer. The depth of the second nearest semi-transparent surface may be determined using a stencil test based on the stencil count to bypass the nearest semi-transparent surface. The second nearest semi-transparent surface may be rendered to an image buffer, and the nearest semi-transparent surface may be rendered to the image buffer.

The invention relates to a particle rendering optimization method, in particular to a rendering optimization method of particles with a high fill rate, which belongs to the technical field of computer graphics. By using off-screen rendering with low resolution, the performance can be greatly improved, and the consumption of a particle system can be more controllable. Although distortion cannot be completely eliminated, an acceptable rendering effect can be achieved by improvement with a fuzzy method, a stencil buffer method and the like.

The invention discloses a visibility analysis rendering method base on a principle of stencil shadow. The method includes steps of establishing a closed first polyhedron along the direction of sight lines for a model of an area which is to be subjected to visibility analysis; rendering the first polyhedron for one time by means of an algorithm, and setting a number which is not a first digit as a second digit in a stencil buffer; constructing a closed second polyhedron within the sight lines; rendering the second polyhedron for two times, wherein obtained values of the stencil buffer comprise the first digit, the second digit, a third digit and a fourth digit; and rendering an area where the value of the stencil buffer is the third digit, setting the area with visible colors, rendering an area where the value of the stencil buffer is the fourth digit, and setting the area with invisible colors. According to the visibility analysis rendering method base on the principle of the stencil shadow, by means of the principle of the stencil shadow, an invisible area is generated, the generated area has obvious edges and is free from distortion , and the accuracy of analysis results can be guaranteed, so that the visibility analysis area can be subjected to high-accuracy rendering.