JPH0477882A - Method and device for plotting triangle polygone - Google Patents

Abstract

PURPOSE:To improve plotting quality by attaining plotting a grid point located in the internal part of a ridgeline obtained virtually except a case that the ridgeline obtained virtually is coincident with the grid point. CONSTITUTION:The depth value of a direction orthogonal with a scanning line and the inclination of color data or a luminance value are calculated, after that, the depth value and the color data or the luminance value are obtained with the grid point of a polygon internal part nearest to a point on a plotting starting side ridgeline obtained virtually as a plotting starting point based on the inclination of the both directions and plane coordinates are obtained with the grid point of the polygon internal part nearest to the point on a plotting ending side ridgeline as a plotting ending point. Space from the plotting starting point to the plotting ending point is interpolated and plotted with the obtained inclination, the depth value of a plotting point and the color data or the luminance value as a initial value. Here, only the grid point located in the internal part of the ridgeine obtained virtually is plotted except a case that the ridgeline obtained virtually is coincident with the grid point. Thus, plotting quality can be improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method and apparatus for drawing triangular polygons, and more specifically, the slope of the triangular polygon is calculated in advance, and the starting and ending points of drawing are determined based on this slope. The present invention relates to a method and apparatus for drawing triangular polygons in which depth values, brightness values, etc. are obtained by linear interpolation between the gaps, and triangular polygons are filled in and drawn based on the obtained depth values, brightness values, etc.

<Conventional technology> Conventionally, the slope of the polyline in the scan line direction is calculated in advance by focusing on the flatness of triangular polygons, and three-dimensional coordinate values and colors are calculated by performing interpolation calculations on the edge line on the drawing start point side. Calculate the data or brightness value and perform interpolation on the edge line at the end of drawing to calculate only the plane coordinate values, and then consider the slope of the polygon in the scan line direction with respect to the interpolated value on the start point side. The drawing start point is obtained by calculating the three-dimensional coordinate value and color data or brightness value of the point on the grid point, and the obtained drawing start point, the plane coordinates of the drawing end side, and the gradient in the scan line direction of the polygon are A method has been proposed in which interpolation calculations are performed based on the above-mentioned information to perform fill-in drawing.

A more detailed explanation will be given by taking as an example the drawing of a triangle shown in FIG. 7(A). However, the plane coordinates of the three vertices of the triangle are PO (xO, yO, zO) and PI (xl, yl.

zl), P2(x2.Y2.z2), and PO,
The ridgeline connecting P2 is the drawing start side.

In this case, the slope of the drawing start side edge line (hereinafter referred to as the left edge line) in the three-dimensional space is d x02/ d
y02= (x2-xO)/(y2-yO), d z
02/d y 02= (z 2-z'o)/(y
2-y O), and the inclination of the right ridgeline in the plane is dxo1/d yo1= (xi-xo)/(yl-y
O), d xl, 2/d y12= (x2-xl,)
/(y2-yl,).

When interpolating the left edge, drawing is performed along the scan line, so the X coordinate is 1.
For the X coordinate, two coordinates, color data, or brightness value, the respective increment values may be cumulatively added.

However, in the following explanation, parts related to color data or brightness values will be omitted, but the same processing as for two coordinate values may be performed.

Therefore, the mth interpolated point PL(m) on the left edge
fxL(m), yL(m), zL(m)) is x L(m) −x L(m-1)+ d x 02
/ d y 02y L(lN) -y L(+n-1
) + 1z L(a) −z L(al-1)+ d
z 02/ d y 02 However, m is the number of scan lines from the minimum value of the X coordinate, x L (0) - x O, y
L(0)-y O,z L(0)-z O. In addition, the mth interpolated point PR (Sho) [xR
(+n), yIi(m)l is x R(m) −
x R (+n edition) → −d x [11, / d y 0
1y1, (m) = y R (■-1) → -1 However, x
R(0)-xO,yIn(0)-yO. (See (B) in the same figure) Note that if the corresponding point is between the vertices PL and P2, the calculations are made in the same way, except that the increment value is different.

Then, the obtained point P L(m) (x L(Ill)
, y I, (m).

Considering zl, (In)l and the slope of the polygon in the scan line direction, zL(m) is corrected in correspondence with the decimal point component dx of xl, (m), and the drawing starting point Ss (x
s, ys.

zs) (see figure (C)). In addition, the white circle in the figure is Ss
The black circle indicates PI (m), the triangle indicates the Z value drawn when no binary correction is performed, and the square indicates the Z value drawn when binary correction is performed. . In addition, for the right edge line, the drawing end point S c (x e, y c
).

Thereafter, interpolation is performed pixel by pixel from the drawing start point Ss to the drawing end point Se along the scan line, and the obtained z value is rounded off to obtain the binary value of the corresponding pixel. Note that color data or brightness values can also be obtained in the same way.

Therefore, by performing drawing based on the obtained binary values, color data, or brightness values, only the lattice points inside the triangular polygon are drawn, as shown in FIG. 3D.

<Problems to be Solved by the Invention> In the above-described triangular polygon drawing method, since the drawing start and end points are obtained by rounding off, when the figure is folded back as shown in FIG. 8(A), the surface Because the same pixel is drawn twice at the intersection of the triangular polygon whose side should be drawn and the triangular polygon whose back side should be drawn, the edge line of the triangle to be drawn on the back side is drawn (same (see Figure (B)), there is a disadvantage that the image quality is significantly degraded.

In addition, when there are two triangular polygons that are extremely close to each other as shown in FIG. 9(A), the modeling coordinate system,
In graphics pipelines, etc., polygon vertex coordinates are floating point data, so they are understood as separate surfaces, but conventional drawing methods perform interpolation calculations based on vertex coordinates converted to integer values after clipping. In the case of odor, it is recognized as an intersecting plane, as shown in FIG. 5(B), and there is also the problem that the image quality is significantly degraded.

<Object of the invention> This invention was made in view of the above problems,
The first object of the present invention is to provide a method and device for drawing triangular polygons that can significantly reduce the frequency of drawing edge lines of back polygons and improve image quality, thereby eliminating the inconvenience caused by each rounding of coordinate values. A second object of the present invention is to provide a method and apparatus for drawing triangular polygons that can improve image quality.

Means for Solving the Problems> In order to achieve the first object, the triangular polygon drawing method of the present invention calculates the depth value in the scan line direction and the gradient of the color direction or brightness value for the triangular polygon. At the same time, calculate the gradient of the depth value and color data or brightness value in the direction perpendicular to the scan line,
Based on the gradients in both directions of the triangular polygon, the depth value and color data or brightness value are obtained using the grid point inside the polygon closest to the point on the virtually obtained drawing start side ridgeline as the drawing start point, and the depth value and color data or brightness value are obtained from the drawing end side ridgeline. Obtain only the plane coordinates with the grid point inside the polygon closest to the upper point as the drawing end point, and use the obtained slope, depth value, and color data or brightness value of the drawing start point as initial values, from the drawing start point to the drawing end point. This is a method of interpolating and drawing.

In order to achieve the above first object, the triangular polygon drawing device of the present invention includes a first gradient calculating means for calculating the gradient of the depth value and color data or brightness value in the scan line direction for the triangular polygon; A second gradient calculation means that calculates the gradient of the depth value and the color data or the brightness value in orthogonal directions, a plane coordinate calculation means that calculates the plane coordinates of the point on the edge line, and a second gradient calculation means that calculates the gradient of the depth value and color data or brightness value in orthogonal directions; , a drawing start point calculation means for obtaining a depth value and color data or a brightness value using a grid point inside a polygon closest to a point on the drawing start side ridgeline obtained virtually as a drawing start point; A drawing end point calculation means that obtains the plane coordinates of the grid point inside the nearest polygon, and interpolates between the drawing start point and the drawing end point using the obtained slope, depth value and color data or brightness value of the drawing start point as initial values. and a drawing means for drawing.

In order to achieve the above second object, the triangular polygon drawing method of the present invention uses vertex data of the triangular polygon including decimal point components before obtaining the grid point inside the polygon that is closest to the point on the drawing start side edge line. is received, and based on the received vertex data, the depth value and color data or brightness value are obtained using the lattice points inside the triangular polygon corresponding to the vertices as the reference for interpolation calculation as vertices, and then the same processing as in the first invention is performed. This is what we do.

In order to achieve the above second object, the triangular polygon drawing device of the present invention, in addition to the second invention, receives vertex data of a triangular polygon including a decimal point component, and performs an interpolation operation based on the received vertex data. The drawing start point calculation means further includes reference point calculation means for obtaining a depth value and color data or brightness value using a grid point inside a triangular polygon corresponding to the reference vertex as the vertex, and the drawing start point calculation means calculates the calculated reference point and Taking into account the gradients in both directions of the triangular polygon, depth values and color data or brightness values are obtained by using the grid point inside the polygon closest to the virtually obtained point on the ridgeline on the drawing start side as the drawing starting point.

Effects〉 If the triangular polygon drawing method of the first invention is as described above,
Calculate the gradient of the depth value and color data or brightness value for the triangular polygon not only in the scan line direction but also in the direction orthogonal to the scan line, and then based on the gradients in both directions, a drawing start side ridgeline that is virtually obtained Depth values and color data or brightness values are obtained using the grid point inside the polygon closest to the upper point as the drawing start point, and only plane coordinates are obtained using the grid point inside the polygon closest to the point on the drawing end edge as the drawing end point. Since the obtained slope, the depth value of the drawing starting point, and the color data or brightness value are used as initial values, the area from the drawing starting point to the drawing ending point is interpolated and drawn, so the virtually obtained edge line is a grid point. Unless they match, only grid points located inside the virtually obtained edge are drawn. Therefore, even if the edges of the triangular polygon on which the front side is drawn and the triangular polygon on which the back side is drawn match, the color of the back side polygon will change only at the point where the virtually obtained edge line matches the grid point. Since there is only a possibility that drawing is performed based on data or brightness values, and there is a very low possibility that a virtually obtained edge line will coincide with a grid point, it is necessary to significantly improve the drawing quality of triangular polygons. I can do it.

In the triangular polygon drawing device of the second invention, the first gradient calculating means and the second gradient calculating means calculate the depth value and color data or brightness value of the triangular polygon not only in the scan line direction but also in the direction orthogonal to the scan line. The plane coordinate calculation means calculates the plane coordinates of a point on the edge line, and the drawing start point calculation means calculates the plane coordinates of the point on the drawing start side edge line and the slope of the triangular polygon in both directions. Based on this, the depth value and color data or brightness value are obtained by setting the grid point inside the polygon closest to the virtually obtained point on the drawing start side ridgeline as the drawing start point. Then, the drawing end point calculating means obtains only plane coordinates with the grid point inside the polygon closest to the point on the drawing end side ridgeline as the drawing end point, and calculates the obtained gradient, depth value, and color data or brightness value of the drawing starting point. As an initial value, the drawing means interpolates and draws from the drawing start point to the drawing end point, so unless the virtually obtained edge line coincides with a grid point, it can be virtually obtained. Only grid points located inside the edges are drawn. therefore,
Similar to the first invention, the drawing quality can be significantly improved.

In the triangular polygon drawing method of the third invention, before obtaining the grid point inside the polygon that is closest to the point on the drawing start side edge line, vertex data of the triangular polygon including decimal point components is received, and the received vertex data Based on this, depth values and color data or brightness values are obtained using the lattice points inside the triangular polygon corresponding to the vertices that are the reference for interpolation calculations as vertices, and then the same processing as in the first invention is performed. Points located inside the triangular polygon can be obtained as vertices that serve as a reference for calculation.

Therefore, even if adjacent triangular polygons are close to each other, the vertices that serve as the reference for interpolation calculations can be obtained as different points, reliably eliminating the inconvenience of drawing as intersecting polygons and improving the drawing quality. can be significantly improved.

In the triangular polygon drawing device of the fourth invention, in addition to the second invention, the reference point calculation means receives vertex data of the triangular polygon including a decimal point component, and performs an interpolation operation based on the received vertex data. Depth values and color data or brightness values are obtained using the lattice points inside the triangular polygon corresponding to the reference vertices as vertices, and the drawing start point calculation means takes into account the gradients in both directions of the calculated reference point and the triangular polygon. Since the depth value, color data, or brightness value is obtained by using the grid point inside the polygon closest to the virtually obtained point on the drawing start side edge line as the drawing start point, the triangular polygon's vertices are used as the reference vertices for interpolation calculations. You can get points located inside. Therefore, even if adjacent triangular polygons are close to each other, the vertices that serve as the reference for interpolation calculations can be obtained as different points, reliably eliminating the inconvenience of drawing as intersecting polygons.1. The drawing quality can be significantly improved.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a flowchart showing an embodiment of the triangular polygon drawing method of the present invention, in which step (2) waits until vertex coordinate values are supplied, and then step (2) calculates the inclination d x / d of the corner edge of the triangular polygon. Y is calculated, and in step (2), the gradient d of the triangular polygon in the scan line direction (hereinafter referred to as the X direction) and in the direction orthogonal to the scan line (hereinafter referred to as the X direction) is calculated.
z / d to calculate the start and end points in the drawing direction (hereinafter referred to as span), and in step (2) calculate the two coordinate values of all grid points between the start and end points and perform drawing, and in step (2), calculate the corresponding triangular polygon. It is determined whether or not the drawing has been completed, and if it is determined that the drawing has not been completed, the process of step (2) is performed again, but if it is determined that the drawing has been completed, the series of processes is terminated. Note that color data or brightness values are also omitted in this embodiment since they are the same as binary interpolation.

For example, as shown in FIG. 2(A), the vertex coordinates are PO(
xO, yO, zO), PI (xl, yl,, zl
), P2 (x2.y2.z2) is given as a triangular polygon, and the y coordinate value is yo < yt < y2,
A more detailed explanation will be given by taking as an example a case where the vertex P1 is located on the right side of the ridge line connecting the vertex POP2.

In this case, the slope of the edge line connecting each vertex in step ■ is d xlO/d ylO= (xl - xO)/ (
yl-yO), dx20/dy20- (x, 2-xO
)/(y2-yO), d x21/d y2+ -(
x2-xl, )/(y2-yl,) is calculated as (
(See Figure 2 (B)), and in step 2, the X direction and the gradient in the X direction of the triangular polygon are d z / d x - ((yl-yO) (z2-zO)
-(y2-yO)(zl-zO)] / ((yl-y
O)(x2-xO)(Y2-y O)(x1-x
O) l, d z/d y= ((x2-xo)(zl-
zO) −(xl-xOHz2-zo)l/((y
l-yO)(x2-xO)(V2-yO)(xl
−x O)]. In other words, if there is a change of one pixel in the X direction inside the triangle, the two coordinate values will be dz/
It can be seen that if the value changes by dx and by 1 pixel in the X direction, the two coordinate values will change by dz/dy.

In step ■, the increment values nz02 and nz02+ for calculating the span start point are set as nz02-a02dz/dx+dz/dyn z02+
-(a02±1.) d z / d x 10 d,
z / dy (however, a02 is dx02/dy02
The largest integer not exceeding a02 is calculated by performing the following calculation: ten is selected when a02 is positive, and ten is selected when a02 is negative. Then, in step (2), when the span increases by 1 in the X direction, the increment value nz02+ or nz02 is selected based on whether or not there is a carry from the decimal point to the X coordinate value of the span start point, and ridgeline interpolation is performed. (See Figure 2 <C>). Therefore, the two coordinate values obtained by edge interpolation become values inside the triangular polygon.

Thereafter, the values of all the grid points between the start and end points of the span calculated in step (2) are calculated by interpolation and drawn.

As a result, when drawing adjacent triangular polygons, the corresponding grid point is drawn twice only if the edge line happens to coincide with the grid point, and in other cases the grid point is It is never drawn twice. Furthermore, the possibility that a ridge line and a grid point coincide by chance is significantly lower than the frequency of occurrence of matching grid points at the boundaries of adjacent triangular polygons when the two coordinate values of the span start and end points are rounded off. , the deterioration in image quality caused by drawing the same grid point twice can be suppressed to a large extent rlJ.

<Embodiment 2> FIG. 3 is a block diagram showing an embodiment of the triangular polygon drawing device of the present invention, in which a vertex coordinate register (1
), an edge/slope calculation unit (2) that calculates the slope of the edge line based on the vertex coordinates, and a polygon slope calculation unit (3) that calculates the X direction and the slope in the X direction of the triangular polygon based on the vertex coordinates. a span start point increment calculation unit (4) that calculates an increment value for calculating the span start point based on the slope of the ridgeline and the slope of the triangular polygon; It has an interpolation section (5) and a span interpolation section (7) that performs interpolation calculations in the span direction based on the edge line interpolation results.

In this embodiment, the portions corresponding to color data or brightness values are omitted because they have the same structure as the portions corresponding to two coordinate values.

Span start point increment calculation unit (4) which is the main point of this invention
is nz −adz / dx + dz /
d ynz4j=(a±1)dz/dx+dz/dy(
However, a is the largest integer that does not exceed dx/d'/, ± is,
10 is selected when a is positive, and - is selected when a is negative) to calculate two types of increment values nzSnz1.

The edge line interpolation unit (5) includes a selector (51), an adder (52), and a cumulative addition register for cumulatively adding an increment value of 1 to the X coordinate value held in the vertex coordinate register (1). (53) and the slope of the edge calculated by the edge slope calculation unit (2) with respect to the X coordinate value held in the point coordinate register (1) as an increment value. Selector (
54L edge slope register (55>, adder (
56) and an accumulation register (57), and a two-coordinate interpolation section which is the most essential aspect of the present invention. This two-coordinate interpolation unit includes a pair of registers (58) and (59) that hold the two increment values nz and nz+ calculated by the span start point increment calculation unit (4), and the output from the adder (5B). a selector (60) that selects the contents of one of the registers as an increment value by being controlled based on a carry signal, a selector (e+) normally used for coordinate interpolation, an adder (62), and an accumulator. It has a register (63).

The span interpolation section (7) cumulatively adds an increment value of 1 to the register (71) that holds the X coordinate value obtained by the X coordinate interpolation section and the X coordinate value obtained by the X coordinate interpolation section. The selector (72), adder (73) and cumulative addition register (74) for Selector (75), register <76) for cumulatively adding directional gradient dz/dx
, an adder (77), and an accumulation register (78).

The operation of the triangular polygon drawing device with the second configuration is as follows.

If the coordinates of the triangle vertices are supplied from the upper processor,
Based on these vertex coordinates, the edge slope calculation unit (2
) calculates the slope of the ridgeline, and also calculates the polygon
The slope calculation unit (3) calculates the X direction and the slope in the X direction of the triangular polygon. Then, two types of increment values nz and nz+ are calculated by the span start point increment calculation unit (4) based on the slope of the ridgeline and the slope of the triangular polygon.

After the initial settings have been made as described above, the X coordinate value of the reference vertex is incremented by 1 by the selector (51), adder (52), and cumulative addition register (53), and at the same time the selector (54) ), the edge slope register (55), the adder (56), and the cumulative addition register (57) cumulatively add the slope of the edge to the X coordinate value of the reference vertex. At the same time as the cumulative addition of values, the two coordinate values are also cumulatively added,
A selector (60) controlled by a carry signal from the adder (56) indicating whether there is a carry from the decimal point or not, and a pair of registers (58) each holding the increment value nZ%nZ+. (59), the selector (61), the adder (62), and the cumulative addition I register (63) cumulatively add the incremental value to the two coordinate values of the reference vertex. In case, always nz
is selected as the increment value, and nz+ is selected as the increment value only when there is a carry from the decimal point. Therefore, the two coordinate values obtained by edge interpolation are values inside the triangular polygon.

If the ridgeline is interpolated as described above, the span start and end points are obtained, so the span interpolation unit (7) only needs to perform interpolation calculations between the span start and end points. y.

Two coordinate values are obtained.

As a result, when drawing adjacent triangular polygons, only if the edge line happens to coincide with a grid point, the corresponding grid point is drawn twice; in other cases, the grid point is drawn twice. It will never happen. Furthermore, the possibility that a ridge line and a grid point coincide by chance is significantly lower than the frequency of occurrence of matching grid points at the boundaries of adjacent triangular polygons when the two coordinate values of the span start and end points are rounded off. , the deterioration in image quality caused by drawing the same grid point twice can be suppressed to a large extent.

<Embodiment 3> FIG. 4 is a flowchart showing another embodiment of the triangular polygon drawing method of the present invention. The difference from the flowchart in FIG. The received point, the point where step ■ is inserted between step ■ and step ■ to calculate the coordinate value of the point inside the triangular polygon closest to the drawing start vertex (hereinafter referred to as the base pointer), and the obtained point. The only point is that the following steps are performed based on the base pointer.

To explain in detail the processing in step (2) above, if the drawing start vertex is the vertex with the minimum X coordinate value, the base pointer BPO is located on the first scan line above the drawing start vertex. It becomes a grid point. Here, if the distance in the X direction between the drawing start vertex and the base pointer BPO is dyo, and the distance in the X direction is dxO (see Figure 5), then the X coordinate value of the base pointer BPO dxBPO1y
The coordinate value dyBPo and the z coordinate value d z BPO are respectively d x BPO-x O+ d x 01dyBPO
-yO+dyO1 dzBPo-zO+ f(dz/dx) Xdxol
It can be easily obtained by performing the operation of 10 ((dz/dy) As a result, there is no guarantee that the vertex coordinates are located inside the triangular polygon, and when drawing adjacent triangular polygons, the vertex coordinates always match, but in this example, the base of the adjacent triangular polygon The meeting pointers will match only if the vertex happens to match the grid point, and the base pointers will not match in any other case.

As shown above, the base/base located inside the triangular polygon
After the pointer is obtained, edge interpolation and span interpolation are performed in the same manner as in the embodiment of FIG. 1 to fill in only the grid points located inside the triangular polygon.

As a result, even if there are two or more triangular polygons that are very close to each other, these triangular polygons can be drawn as non-intersecting planes, and the drawing quality can be improved.

<Embodiment 4> FIG. 6 is a block diagram showing another embodiment of the triangular polygon drawing device of the present invention. The difference from the block diagram of FIG. Base pointer calculation that calculates the X coordinate value, Part (81) (82)
The only point is that it further has (83).

The base pointer calculation unit (81) d　xBPO=xO+d　x.

The base pointer calculation unit (82) calculates the X coordinate value converted into an integer by performing the calculation: dyBPO-yQ 10dy.

The base pointer calculation unit (82) calculates the X coordinate value converted into an integer by performing the calculation: clzBPO−zO+ ((dz/dx)xdxol
Two coordinate values in the x and X coordinate values are calculated by performing the calculation +f (d z / d y ) X d y 01.

The operation of the triangular polygon drawing device having the above configuration is as follows.

Vertex coordinates with components below the decimal point are supplied from the upper processor, and based on the vertex coordinates, the edge/slope calculation section (2) calculates the slope of the edge line, and the polygon/slope calculation section (3) calculates the slope of the triangular polygon. The X direction and the gradient in the X direction are calculated. In addition, the base pointer calculation unit (81) calculates the drawing start vertex and the base pointer.
Calculate the distance in the X direction from pointer BPO to dyo,
A calculation of ynpo-yo+dyO is performed to calculate the y-coordinate value dynpo of the base pointer BPO. Similarly,
The base pointer calculation unit (82) calculates dxO as the distance in the X direction between the drawing start vertex and the base life pointer BPO, and performs the calculation d x BPO - x O + d x O to calculate the X of the base pointer BPO. Coordinate value dxBP
Calculate o. Then, the base fist pointer calculation unit (83
), based on the above intervals dxO, dyO, d zB
PO−zO+ ((d z/dx) Xdxo 1 +
f (dz/dy)XdyO) to calculate the two coordinate values d of base pointer BPO.
z Calculate BPO.

Thereafter, based on the obtained base pointer BPO, edge line interpolation and span interpolation are performed in the same way as in the block diagram of FIG. 3, so that only grid points located inside the triangular polygon can be drawn.

As a result, even if there are two or more triangular polygons that are very close to each other, these triangular polygons can be drawn as non-intersecting planes, and the drawing quality can be improved.

<Effects of the Invention> As described above, the first invention draws only the grid points located inside the virtually obtained ridgeline, except when the virtually obtained ridgeline coincides with the lattice point. possible, and in turn,
Even if the edges of the triangular polygon on which the front side is drawn and the triangular polygon on which the back side is drawn match,
This has the unique effect of significantly improving the drawing quality of triangular polygons.

The second invention also allows drawing only grid points located inside the virtually obtained ridgeline, unless the ridgeline obtained virtually coincides with a lattice point, and as a result, the surface is drawn. Even when the edges of the triangular polygon and the triangular polygon whose back side is drawn match, the unique effect is that the drawing quality of the triangular polygon can be significantly improved.

The third invention selects a lattice point located inside a triangular polygon as the drawing start vertex, so even if adjacent triangular polygons are close to each other, the vertices serving as the reference for interpolation calculation can be set to different points. This has the unique effect of reliably eliminating the inconvenience of drawing as intersecting polygons and significantly improving the drawing quality of triangular polygons.

The fourth invention also selects a lattice point located inside a triangular polygon as the drawing start vertex, so even if adjacent triangular polygons are close to each other, the vertices serving as the reference for interpolation calculation can be set to different points. This has the unique effect of reliably eliminating the inconvenience of drawing as intersecting polygons and significantly improving the drawing quality of triangular polygons.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of the triangular polygon drawing method of the present invention, FIG. 2 is a schematic diagram explaining the edge line interpolation operation, and FIG. 3 is a block diagram showing an embodiment of the triangular polygon drawing device of the present invention. 4 is a flowchart showing another embodiment of the triangular polygon drawing method of the present invention, FIG. 5 is a schematic diagram illustrating the base pointer calculation operation, and FIG. 6 is a flow chart showing another embodiment of the triangular polygon drawing method of the present invention. FIG. 7 is a schematic diagram illustrating a conventional example of a triangular polygon drawing method; FIGS. 8 and 9 are schematic diagrams illustrating disadvantages of the conventional triangular polygon drawing method.

Claims (1)

[Claims] 1. Calculate the depth value and the gradient of color data or brightness value in the scan line direction for a triangular polygon, and also calculate the gradient of the depth value and color data or brightness value in the direction orthogonal to the scan line. , based on the gradients in both directions of the triangular polygon, the depth value and color data or brightness value are obtained using the grid point inside the polygon closest to the virtually obtained point on the ridgeline on the drawing start side as the drawing start point, and the depth value and color data or brightness value are obtained on the drawing end side. Obtain only plane coordinates with the grid point inside the polygon closest to the point on the edge as the drawing end point, and use the obtained gradient, depth value, and color data or brightness value of the drawing start point as initial values to calculate the distance from the drawing start point to the drawing end point. A method for drawing triangular polygons that is characterized by drawing by interpolating between them. 2. The first step of calculating the depth value in the scan line direction and the gradient of color data or brightness value for the triangular polygon.
a gradient calculating means, and a second calculating means for calculating gradients of depth values and color data or brightness values in a direction perpendicular to the scan line.
Gradient calculation means (3) and plane coordinate calculation means (51) (52) (53) (54) for calculating the plane coordinates of points on the ridgeline.
Considering (55), (56), and (57), and the gradient in both directions of the triangular polygon, the depth value and color are set as the drawing start point at the grid point inside the polygon that is closest to the point on the virtually obtained drawing start side ridgeline. Drawing start point calculation means (4) (58) (59) (60) (61) (6) for obtaining data or brightness values
2) (63) and a drawing end point calculation means (
4) (58) (59) (60) (61) (62) (63
) and a drawing means (71) (72) that interpolates and draws from the drawing start point to the drawing end point using the obtained gradient, depth value and color data or brightness value of the drawing start point as initial values.
(73), (74), (75), (76), and (77). 3. Prior to obtaining the grid point inside the polygon that is closest to the point on the drawing start side edge, receive the vertex data of the triangular polygon that includes decimal point components, and use the received vertex data to determine the vertices that will be the reference for interpolation calculations. A method for drawing a triangular polygon according to claim 1, in which depth values and color data or brightness values are obtained using grid points inside corresponding triangular polygons as vertices. 4. Receive vertex data of a triangular polygon that includes a decimal point component, and obtain depth values and color data or brightness values based on the received vertex data, with lattice points inside the triangular polygon corresponding to the vertices serving as the reference for interpolation calculations as vertices. It further includes reference point calculation means (81), (82), and (83), and drawing start point calculation means (4), (58), and
59) (60) (61) (62) (63) takes into account the calculated reference point and the gradient in both directions of the triangular polygon, and calculates the inside of the polygon that is closest to the point on the drawing start side edge line that is virtually obtained. 3. The triangular polygon drawing device according to claim 2, wherein the depth value and color data or brightness value are obtained using a lattice point as a drawing starting point.