JPH0224785A - Method and device for shadowing processing - Google Patents

Abstract

PURPOSE:To sharply shorten time required for shadowing processing by deciding whether the light irradiated face of a graphic to be drawn is the whole surface, a part of the surface or no existence, and at the time of drawing the graphic to be drawn on a view coordinate system, executing drawing processing based upon shadow information corresponding to the unirradiated area on the basis of the decided result. CONSTITUTION:A light source conversion matrix is determined so that converted coordinate data are included in a light source depth buffer 6. The light source coordinate conversion of the coordinate data of a polygon constituting a graphic to be shadowed is executed, converted coordinate data are obtained, whether the light irradiated face is the whole surface, a part of the surface or no existence is decided on the basis of the coordinate data, an identification (ID) data are supplied to a segment memory 1, and depth data of each picture element are written in the buffer 6. The view coordinate conversion of each polygon in a view volume is executed. Then, the sort of the ID data is decided and drawing corresponding to the decided result is executed to obtain shadowed drawing data.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a shadow processing method and a device thereof, and more specifically, to a shadow processing method and apparatus thereof, and more specifically, to achieve a three-dimensional representation of the entire screen using a depth buffer algorithm. The present invention relates to a shadow processing method and apparatus.

<Prior art and problems to be solved by the invention> There has been a strong demand for more sophisticated display in computer graphics, and specifically, not only three-dimensional representation of individual figures to be drawn, but also Research has begun on providing a shape processing function that can also perform three-dimensional representation of the entire figure to be drawn.

This shape processing function: ■ Assumes a line of sight connecting the point corresponding to each pixel on the projection plane and the fulcrum, obtains the intersection point with the nearest figure that intersects with the line of sight, and obtains a line segment connecting the intersection point and the light source. , detect a figure that intersects the obtained line segment, and shadow the pixels on the detected figure. ■ Project the sides of one figure onto another figure, and then project it onto the projection plane. A method to obtain the shadow area on the scanning line by projecting it, and ■ Obtain the shadow area by applying the same algorithm as hidden surface processing to each figure when viewed from the light source, and then calculate the hidden surface area for each figure when viewed from the viewpoint. A method has been proposed in which processing is performed and the shadow area is mapped onto a projection plane.

Among these, the shading processing method (■) can display a display that has undergone some form processing using a simple algorithm, but it requires a long processing time because processing must be performed for each pixel. The problem is that it becomes.

In addition, the shading processing method (■) does not process each pixel, but each scanning line, so it can reduce the processing time compared to the shading processing method (2). However, there is a problem that the required time cannot be sufficiently shortened.

Also, in the shading processing method in the above direction, especially
When a free-form surface expressed by the following parametric equation is targeted, the calculation time becomes extremely long, and as a result, the time required for shape processing also becomes extremely long.

Furthermore, the shadow processing method (■) obtains shadow areas using the same algorithm as the hidden surface processing method, so it can reduce the time required, but it requires mapping processing, so additional data is As the amount increases, the configuration and processing become complicated, and all pixels are subject to shape processing, so there is a problem that the time required for shape processing cannot be sufficiently shortened. Furthermore, since it is necessary to process the relative relationship between surfaces, there is a problem that there is a limit to the target figures that can be processed.

Taking these problems into consideration, a method of performing shape processing by applying a depth buffer algorithm to both the light source coordinate system and the viewpoint coordinate system ("Simple contrast imaging method using the Z-buffer method") was proposed by Kazusho Shimizu in 3 Information Processing Society of Japan 30th (early 1985) National Convention) is provided.

However, since this method does not consider the range of shapes at all, unnecessary shape processing must be performed, and sufficient accuracy cannot be obtained even in areas where shape processing is required. Coordinate transformations, coordinate value comparisons, etc. necessary for shape processing are processed pixel by pixel, resulting in an extremely large amount of calculations and unnecessary calculations. There is a problem that the effect of shortening the time required for shape processing cannot be achieved.

<Object of the invention> This invention was made in view of the above problems,
It is an object of the present invention to provide a novel shading processing method and apparatus that can significantly reduce the number of pixels to be processed and the time required for shape processing.

Means for Solving the Problems> In order to achieve the above object, the shading processing method of the present invention extracts drawing target figure data to be shadowed from drawing target figure data, and changes the light source direction in the depth direction. Convert the figure data to be drawn on the light source coordinate system, determine whether the surface of the converted figure to be drawn is illuminated by light, a whole surface, a part of the surface, or no surface at all, and set the viewing direction as the depth direction. In this method, when drawing a figure to be drawn on the view coordinate system, drawing processing is performed based on shadow information in correspondence with areas that are not illuminated by light based on the determination result.

However, the figure data to be drawn is initially defined on the world coordinate system, and by performing matrix operations, the figure data to be drawn on the light source coordinate system and the figure data to be drawn on the view coordinate system are obtained. It is preferable.

In addition, all drawing target figures are drawn with hidden surface processing applied, and whether all pixels composing each drawing target figure have been written, only some pixels, or no pixels have been written. It is preferable to determine whether the surface exposed to light is the entire surface, a portion of the surface, or no surface at all, based on whether writing is not performed.

To achieve the above object, the shading processing device of the present invention includes a segment memory, an extraction means, a view coordinate conversion means, a light source coordinate conversion means, a line-of-sight depth buffer, a light source depth buffer, It has a selection means and a frame memory.

The above segment memory stores data for multiple figures to be drawn defined on the world coordinate system, and also determines whether the surface that is illuminated by light is the entire surface, a part of the surface, or none at all, corresponding to each figure to be drawn. The extraction means extracts the figure data to be shaded from the drawn figure data, and the view coordinate conversion means extracts the figure data to be shaded from the drawn figure data. The light source coordinate conversion means performs coordinate conversion to the light source coordinate system based on the extracted figure data, and the line-of-sight depth buffer performs the view coordinate conversion. The light source depth buffer stores pixel data obtained based on data subjected to light source coordinate transformation, and also stores pixel data obtained based on data subjected to light source coordinate transformation. The selection means selects pixel data to be written based on the identification data and depth data read from the segment memory, and the frame memory generates identification data and supplies it to the segment memory. , selected luminance data is written corresponding to a large number of pixels on the view coordinate system.

However, the above selection means selects the information data to be written based on the identification data, the depth data read from the light source depth buffer, and the depth data obtained based on the data subjected to light source coordinate transformation. There may be.

The light source depth buffer also generates priority data in the depth direction for each figure to be drawn and supplies it to the segment buffer, and the selection means selects information data to be written based on the identification data and priority data. It is preferable that the

With the above shading processing method, the drawing target figure data to be shadowed is extracted from the drawing target figure data, and the drawing target figure data is converted to the drawing target figure data on the light source coordinate system with the light source direction as the depth direction. After the conversion, it is determined whether the surface that is illuminated by light is the entire surface, only a portion of the surface, or does not exist at all for the target figure to be drawn after the conversion. Then, when converting the graphic data to be drawn into graphic data on the view coordinate system and visually displaying it with hidden surface processing applied, it is possible to correspond to areas that are not illuminated based on the above discrimination results. By performing drawing processing based on shadow information, it is possible to perform three-dimensional drawing that has been subjected to shape processing.

When the drawing target figure data is initially defined on the world coordinate system and the drawing target figure data on the light source coordinate system and the drawing target figure data on the view coordinate system are obtained by performing matrix calculation, It is only necessary to define the figure data to be drawn on the world coordinate system, and by performing the former matrix calculation, it is possible to determine the surface that the light hits, and by performing the latter matrix calculation, it is possible to perform hidden surface processing drawing. can be done.

In addition, all the corresponding figures to be drawn are drawn with hidden surface processing applied, and whether all the pixels that make up each figure to be drawn have been written, or only some of the pixels have been written, and the pixel When determining whether the surface that is illuminated by light is the entire surface, a portion of the surface, or does not exist at all based on whether the surface is not written at all, hidden surface processing is applied to all pixel data that constitutes the figure to be drawn. It is only necessary to write in the current state, and accurate determination can be made based on the actually written pixel data.

To explain in more detail, if some processing is performed on all the figures defined on the world coordinate system, some processing is applied only to the necessary areas on all the figures existing in the view volume on the view coordinate system. By doing so, a three-dimensional display can be performed as a whole, but since the area to be subjected to shape processing becomes significantly larger, the amount of calculation required increases significantly.

However, in this invention, drawing object figure data to be shadowed is extracted from figures defined on the world coordinate system and converted to drawing object figure data on a light source coordinate system in which the light source direction is the depth direction. Therefore, it is only necessary to perform calculations on the minimum number of figures necessary, and the amount of calculations can be greatly reduced, and sufficient precision in the light source coordinate system can be achieved.

Then, by simply displaying the shapes defined on the view coordinate system and existing within the view volume three-dimensionally based on the determination results for the minimum necessary number of shapes, the shape that has undergone some processing can be displayed. The entire image can be displayed three-dimensionally.

With the shading processing device configured as above, multiple pieces of figure data to be drawn defined on the world coordinate system are stored in the segment memory, so the extraction means extracts only the figure data to be shadowed. Then, graphic data on the light source coordinate system can be obtained by the light source coordinate conversion means, and the obtained graphic data can be stored in the light source depth buffer. Therefore, the light source depth buffer holds only the depth data of the pixel located closest to the light source. Then, while storing pixel data in the light source depth buffer, it indicates whether the surface to be processed is entirely illuminated by light, only a part of the surface is illuminated, or is not illuminated at all. Identification data can be generated and stored at appropriate locations in the segment memory.

After that, by reading the figure data from the segment memory and obtaining the figure data on the view coordinate system by the view coordinate conversion means, and storing the obtained figure data in the line-of-sight depth buffer, the pixel located closest to the line-of-sight side is Only depth data is retained.

Therefore, depending on the identification data read from the segment memory, there are states in which the entire area should be drawn based on shadow information, states in which it should be drawn based on color information, and states in which only a portion of the area should be drawn based on shadow information. The desired state is selected by the selection means, and the figure belonging to the view volume is written into the frame memory based on the selected information, so that visual display can finally be performed based on the contents of the frame memory.

The selection means selects the information data to be written based on the identification data, the depth data read from the light source depth buffer, and the depth data obtained based on the data subjected to the light source coordinate transformation. In some cases, when it is necessary to perform shape processing based on shadow information only on some areas, depth data is compared for each pixel obtained by performing interpolation calculations to identify the shadow area. It can be determined whether or not.

In addition, the light source depth buffer also generates priority data in the depth direction for each figure to be drawn and supplies it to the segment buffer, and the selection means selects the information data to be written based on the identification data and priority data. If the area is a shadow area or not, it can be determined just by comparing the priority data, so there is no need to compare the depth data for each pixel, and it is not necessary to compare the depth data for each pixel. The required amount of computation can be significantly reduced, and the required time can also be significantly shortened.

<Example> FIG. 1 is a flowchart illustrating the shading processing method of the present invention. In step (2), a light source conversion matrix is determined so that the coordinate data after the conversion fits within the light source depth buffer. Then, in step (2), a light source coordinate transformation is performed on the coordinate data of the polygons constituting the figure to be shadowed to obtain the transformed coordinate data, and based on this coordinate data, light is applied in step (2). Is the surface entirely (all visible polygons) or partially (
It is determined whether there are any partially visible polygons (all invisible polygons), and identification data is supplied to the segment memory, and depth data for each pixel is written to the light source depth buffer. Then, in step (2), view coordinate transformation is applied to each polygon within the view volume.

However, when performing this coordinate transformation, the transformation processing is performed not only on the normal vector and the light source vector but also on the coordinate data after the above transformation. Thereafter, the type of identification data is determined in step (2), and drawing data corresponding to the determination result is performed in any one of steps (2) and (2), thereby obtaining drawing data that has been subjected to some form processing.

The process in step ■ above corresponds to the case where the identification data is fully visible data, and is the process of drawing the entire polygon with shading, and the process in step ■ corresponds to the case where the identification data is fully invisible data. For example, it is a process of drawing based on shadow information such as ambient light, and the process of step (2) interpolates not only the coordinate data on the view coordinate system but also the coordinate data after the above transformation, This process selects drawing (drawing or shading) based on shadow information depending on whether the interpolated depth value is greater than or equal to the depth data stored in the light source depth buffer.

Therefore, if the above shadow processing method is adopted,
When drawing to the frame memory, there is no need to determine what form processing is required for each pixel for all visible polygons and all invisible polygons, and only for partially visible polygons. It is only necessary to determine whether shape processing is necessary or not, and it is also possible to limit the shape range, so the overall amount of calculation can be significantly reduced, and the shape display can be performed at high speed. .

FIG. 2 is a block diagram schematically showing an embodiment of the shading processing device of the present invention, in which graphic data defined on the world coordinate system supplied from a higher-level processor (not shown) and identification data to be described later are stored. Segmented memory (
1) and graphic data read out from the segment memory (1) through a clip section (not shown).
A coordinate conversion unit (2) that performs light source coordinate conversion and line-of-sight coordinate conversion, and a light source side interpolation calculation unit (3) that performs interpolation calculations using the data that has been subjected to light source coordinate conversion as input, and obtains each pixel data on the light source coordinate system. ) and the line-of-sight side interpolation calculation unit (4), which performs interpolation a's using the data subjected to the line-of-sight ring transformation as input and obtains each pixel data on the line-of-sight coordinate system, and the output from the coordinate transformation unit (2). a luminance interpolation calculation section (5) that performs interpolation calculations using input luminance data; and a light source depth buffer (6) that sequentially stores pixel data obtained by the light source side interpolation calculation section (3) based on a depth buffer algorithm. , a line-of-sight depth buffer (7) that sequentially stores pixel data obtained by the line-of-sight side interpolation calculation unit (4) based on a depth buffer algorithm, and a line-of-sight depth buffer (7).
A frame memory (8) in which the writing of luminance data is controlled by a depth flag output from the frame memory (8), depth data output from the light source side interpolation calculation unit (3), depth data read from the light source depth buffer (6), The data is written to the frame memory (8) based on the depth data output from the line-of-sight side interpolation calculation unit (4), the depth data read from the line-of-sight depth buffer (7), and the identification data read from the segment memory (1). and a comparator (9) for selecting luminance data to be input.

Further, the light source depth buffer (6) holds only the depth data of the pixel located closest to the light source among the sequentially supplied pixel data on the light source coordinate system, and also holds the depth data of the pixel located closest to the light source side. All visible data, all invisible data, and partially visible data are generated depending on whether all pixel data has been written to the light source depth buffer (6) or no pixel data has been written, and this data is used as identification data. The data is supplied to the segment memory (1) as follows. FIG. 3 is a block diagram schematically showing the configuration of a device that generates the above identification data, in which polygon data is sequentially generated within the range to which the volume clip processing has been performed, and in the judgment unit 00), the light source It is determined whether all pixel data match the stored depth data by comparing it with the depth data of the light source depth buffer (6) that has been subjected to hidden surface processing on the coordinate system, and if all the pixel data match. If they do not match at all, all invisible data is generated, and if only a portion of them matches, partial visible data is generated and supplied to the segment memory (1).

The operation of the shading processing device having the above configuration is as follows.

A segment memory (1) is sequentially supplied with a plurality of graphic data defined on the world coordinate system from a higher-level processor (not shown) and stored therein. An identification data storage area (not shown) is allocated to each graphic.

Therefore, by performing light source coordinate transformation on the figure data read out from the segment memory (1), each figure is defined on the light source coordinate system with the arrow ray in FIG. By performing volume clip processing, only the figures included in the area indicated by the dotted chain line in Figure B are subjected to depth buffer processing, and conversely, view coordinate transformation is performed on the figure data read from the segment memory (1). Then, each figure is defined on the view coordinate system whose depth direction is arrow A in Fig. 4, and by further performing view volume clip processing,
Only the figures included in the area indicated by the medium broken line undergo depth buffer processing. However, the data to which the view coordinate transformation is performed includes not only vertex information such as normal vectors and light source vectors, but also pixel data obtained by light source coordinate transformation. Then, the depth data of the pixels constituting the polygon is written into the light source depth buffer (6), and identification data is generated and stored in the corresponding area of the segment memory (1).

Therefore, in the comparator (9), the segment memory (1
) The necessary processing is selected in accordance with the identification data read from ), and a frame memo is created based on the corresponding information (January 8).
Writing is performed. To explain in more detail, when the identification data is all visible data, there is no need to perform any form processing at all, so the brightness data IO obtained by performing shading processing by the brightness interpolation calculation unit (5) is sent to the comparator ( 9) and write it into the frame memory (8). In addition, when the identification data is completely invisible data, since no light hits the entire surface, for example, luminance data corresponding to ambient light is selected by the comparator (9) as the shadow information Is, and the frame memory
Just write in 8). Further, when the identification data is partially visible data, the data on the view coordinate system is interpolated, and the coordinate data on the light source coordinate system is interpolated. Then, the depth data ZL interpolated on the light source coordinate system is compared with the depth data ZB stored in the light source depth buffer (6), and ZL-ZB
In this case, it is sufficient to select the brightness data ■0 obtained by performing shading processing and write it to the frame memory (8), and conversely, if ZL<ZB, select the shadow information 1s and write it to the frame memory (8). Just write in (8).

Figure 5 shows a three-dimensional display within the view volume that has been subjected to the shape processing as described above. Achieves three-dimensional expression.

As is clear from the above explanation, in this embodiment, it is no longer necessary to determine whether or not shape processing is required for all pixels, and it is no longer necessary to determine whether shape processing is required for each pixel for only some polygons. Since it is only necessary to determine whether or not to display the image, it is possible to significantly shorten the time required for processing the image and to ensure high-speed display.

<Embodiment 2> FIG. 6 is a block diagram showing another embodiment, and the difference from the above embodiment is that the light source depth buffer (6) is equipped with a device ( 6P), the generated priority data is also stored in the segment memory (1), and the comparator (9a) is controlled by the priority data read from the segment memory (1) and the device (BP), respectively. The only difference is that the comparator (9) is replaced.

To explain in more detail, depth buffer for light source (6)
The magnitude relationship between the depth data that has already been written and the depth data that has been supplied is compared, and it is determined whether all of the pixel data that makes up the polygon is located closest to the light source. Then, priority data is generated only when it is determined. Thereafter, similar processing is performed only on polygons for which priority data has not been generated, and priority data is sequentially generated. below,
Priority data can be generated for all polygons in the same way.

Therefore, in the case of this embodiment, the frame memory (
When writing data to 8), when drawing a partially visible polygon, it is possible to determine whether drawing is based on shading data 10 or shadow information Is by simply comparing ql, briolite, and a number, and what type of shape processing is performed. can be further simplified.

As is clear from the above explanation, in any of the embodiments, the amount of required calculations can be significantly reduced, and therefore the drawing speed can be significantly improved even when any shape processing is performed. Moreover, it can easily handle multiple free-form surfaces. Furthermore, since volumes of any shape can be set, the number of shapes to be processed can be reduced, and from this point of view as well, the drawing speed can be significantly improved.

Note that the present invention is not limited to the above-described embodiments; for example, it is possible to divide the coordinate conversion section into one for light source coordinate conversion and one for view coordinate conversion, and it is also possible to use a selector instead of a comparator. In addition, various design changes can be made without changing the gist of the present invention.

<Effects of the Invention> As described above, the first invention can reduce the number of figures that need to be determined for each pixel, and therefore greatly reduce the amount of calculations. I can do it,
Moreover, since the drawing object figure data to be shadowed is extracted and converted into the drawing object figure data on the light source coordinate system in which the light source direction is the depth direction, calculations can be performed only on the minimum necessary figures. If possible, the amount of calculations can be further reduced, which has the unique effect of significantly increasing the drawing speed in a state where some form processing is performed.

The second invention is that it is only necessary to define the figure data to be drawn on the world coordinate system, and by performing the former matrix calculation, it is possible to determine the surface on which the light hits, and by performing the latter matrix calculation. Hidden surface processing drawing can be performed using this method, which has the unique effect of simplifying the definition of graphic data to which shape processing should be applied.

The third invention is to simply write all the pixel data constituting the figure to be drawn with hidden surface processing applied, and it is possible to easily and quickly obtain accurate information based on the actually written pixel data. This has the unique effect of being able to determine the state.

The fourth invention provides a state in which the entire region should be drawn based on the shadow information, a state in which the entire region should be drawn based on the color information, and a state in which the entire region should be drawn based on the color information, and a state in which the entire region should be drawn based on the shadow information, in correspondence with the identification data read out from the segment memory. The state to be drawn is selected based on
Since the shape belonging to the view volume is written to the frame memory based on the selected information, what kind of shape processing should be performed only when the state to be drawn is selected based only partially on the shadow information? All you have to do is determine whether or not
In other cases, the same processing can be applied to the entire surface, which reduces the need to judge which type of processing is necessary.Furthermore, since any type of volume can be set, the range that requires processing can be reduced. This has the unique effect of being able to further limit the amount of space required, and significantly speeding up the drawing speed.

The fifth invention is to compare depth data for each pixel obtained by performing interpolation calculations in a state where it is necessary to perform some shape processing based on shadow information only on a part of the region. It has the unique effect of being able to determine whether it exists or not.

In the sixth invention, it is possible to determine whether or not it is a shadow area simply by comparing the priority data, so there is no need to compare depth data for each pixel, and it is not necessary to compare the depth data for each pixel. It has the unique effect of being able to significantly reduce the amount of calculations and significantly reducing the required time.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an example of the shading processing method of the present invention, FIG. 2 is a block diagram schematically showing an embodiment of the shading processing device of the present invention, and FIG. 3 is a device for generating identification data. FIG. 4 is a schematic diagram illustrating view coordinate transformation and light source coordinate transformation; FIG. 5 is a schematic diagram illustrating a drawing example after shape processing; FIG. 6 FIG. 3 is a block diagram schematically showing another embodiment.

Claims (1)

[Claims] 1. Extract the drawing target figure data to be shadowed from the drawing target figure data and converting it into drawing target figure data on a light source coordinate system with the light source direction as the depth direction, and drawing after conversion. It is determined whether the surface of the target figure that is illuminated by light is the entire surface, a part of the surface, or there is no surface at all, and based on the determination result, when drawing the target figure on the view coordinate system with the line of sight direction as the depth direction, A shading processing method characterized in that drawing processing is performed based on shadow information Is in correspondence with areas that are not illuminated by light. 2. The figure data to be drawn is initially defined on the world coordinate system, and the figure data to be drawn on the light source coordinate system and the figure data to be drawn on the view coordinate system are obtained by performing matrix operations. The shading processing method described in scope 1. 3. Draw all the figures to be drawn with hidden surface processing applied, and check whether all the pixels that make up each figure to be drawn have been written, only some pixels, or no pixels at all. Claim 1: It is determined whether the surface to which light is applied is the entire surface, a part of the surface, or no surface at all based on whether there is any writing.
The shading processing method described in the section. 4. Storage of data for multiple figures to be drawn defined on the world coordinate system, and identification indicating whether the surface exposed to light is the entire surface, a part of the surface, or none at all, corresponding to each figure to be drawn. A segment memory (1) for storing data, an extraction means (2) for extracting figure data to be shadowed from drawing figure data, and a view for performing coordinate transformation to a view coordinate system based on the figure data to be drawn. A coordinate transformation means (2), a light source coordinate transformation means (2) that performs coordinate transformation to a light source coordinate system based on extracted figure data, and stores pixel data obtained based on data subjected to view coordinate transformation. A line-of-sight depth buffer (7) and a light source that stores depth data obtained based on data subjected to light source coordinate transformation, generates identification data corresponding to the figure to be drawn, and supplies the generated identification data to the segment memory (1). a depth buffer (6), and selection means (9) for selecting information data I0 and Is to be written based on the identification data and depth data read from the segment memory (1);
A shading processing device comprising a frame memory (8) into which selected information data is written corresponding to a large number of pixels on a view coordinate system. 5. The selection means (9) selects the information data to be written based on the identification data, the depth data read from the light source depth buffer (6), and the depth data obtained based on the data subjected to the light source coordinate transformation. The shading processing device according to claim 4, wherein the shading processing device is selected. 6. The light source depth buffer (6) also generates priority data in the depth direction for each figure to be drawn and supplies it to the segment memory (1), and the selection means (9) inputs identification data and priority data. The shading processing device according to claim 4, wherein information data to be written is selected based on the shading processing device.