1 /* $Id: s_aaline.c,v 1.8 2001/04/10 15:46:51 brianp Exp $ */
4 * Mesa 3-D graphics library
7 * Copyright (C) 1999-2001 Brian Paul All Rights Reserved.
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
16 * The above copyright notice and this permission notice shall be included
17 * in all copies or substantial portions of the Software.
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
23 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 #include "swrast/s_aaline.h"
30 #include "swrast/s_pb.h"
31 #include "swrast/s_context.h"
32 #include "swrast/swrast.h"
41 * Info about the AA line we're rendering
45 GLfloat x0
, y0
; /* start */
46 GLfloat x1
, y1
; /* end */
47 GLfloat dx
, dy
; /* direction vector */
48 GLfloat len
; /* length */
49 GLfloat halfWidth
; /* half of line width */
50 GLfloat xAdj
, yAdj
; /* X and Y adjustment for quad corners around line */
51 /* for coverage computation */
52 GLfloat qx0
, qy0
; /* quad vertices */
56 GLfloat ex0
, ey0
; /* quad edge vectors */
66 GLfloat rPlane
[4], gPlane
[4], bPlane
[4], aPlane
[4];
70 GLfloat srPlane
[4], sgPlane
[4], sbPlane
[4];
71 /* DO_TEX or DO_MULTITEX */
72 GLfloat sPlane
[MAX_TEXTURE_UNITS
][4];
73 GLfloat tPlane
[MAX_TEXTURE_UNITS
][4];
74 GLfloat uPlane
[MAX_TEXTURE_UNITS
][4];
75 GLfloat vPlane
[MAX_TEXTURE_UNITS
][4];
76 GLfloat lambda
[MAX_TEXTURE_UNITS
];
77 GLfloat texWidth
[MAX_TEXTURE_UNITS
], texHeight
[MAX_TEXTURE_UNITS
];
83 * Compute the equation of a plane used to interpolate line fragment data
84 * such as color, Z, texture coords, etc.
85 * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
86 * z0, and z1 are the end point values to interpolate.
87 * Output: plane - the plane equation.
89 * Note: we don't really have enough parameters to specify a plane.
90 * We take the endpoints of the line and compute a plane such that
91 * the cross product of the line vector and the plane normal is
92 * parallel to the projection plane.
95 compute_plane(GLfloat x0
, GLfloat y0
, GLfloat x1
, GLfloat y1
,
96 GLfloat z0
, GLfloat z1
, GLfloat plane
[4])
100 const GLfloat px
= x1
- x0
;
101 const GLfloat py
= y1
- y0
;
102 const GLfloat pz
= z1
- z0
;
103 const GLfloat qx
= -py
;
104 const GLfloat qy
= px
;
105 const GLfloat qz
= 0;
106 const GLfloat a
= py
* qz
- pz
* qy
;
107 const GLfloat b
= pz
* qx
- px
* qz
;
108 const GLfloat c
= px
* qy
- py
* qx
;
109 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
116 const GLfloat px
= x1
- x0
;
117 const GLfloat py
= y1
- y0
;
118 const GLfloat pz
= z0
- z1
;
119 const GLfloat a
= pz
* px
;
120 const GLfloat b
= pz
* py
;
121 const GLfloat c
= px
* px
+ py
* py
;
122 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
123 if (a
== 0.0 && b
== 0.0 && c
== 0.0 && d
== 0.0) {
140 constant_plane(GLfloat value
, GLfloat plane
[4])
149 static INLINE GLfloat
150 solve_plane(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
152 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
156 #define SOLVE_PLANE(X, Y, PLANE) \
157 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
161 * Return 1 / solve_plane().
163 static INLINE GLfloat
164 solve_plane_recip(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
166 const GLfloat denom
= plane
[3] + plane
[0] * x
+ plane
[1] * y
;
170 return -plane
[2] / denom
;
175 * Solve plane and return clamped GLchan value.
178 solve_plane_chan(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
180 GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2] + 0.5F
;
183 else if (z
> CHAN_MAXF
)
184 return (GLchan
) CHAN_MAXF
;
185 return (GLchan
) (GLint
) z
;
190 * Compute mipmap level of detail.
192 static INLINE GLfloat
193 compute_lambda(const GLfloat sPlane
[4], const GLfloat tPlane
[4],
194 GLfloat invQ
, GLfloat width
, GLfloat height
)
196 GLfloat dudx
= sPlane
[0] / sPlane
[2] * invQ
* width
;
197 GLfloat dudy
= sPlane
[1] / sPlane
[2] * invQ
* width
;
198 GLfloat dvdx
= tPlane
[0] / tPlane
[2] * invQ
* height
;
199 GLfloat dvdy
= tPlane
[1] / tPlane
[2] * invQ
* height
;
200 GLfloat r1
= dudx
* dudx
+ dudy
* dudy
;
201 GLfloat r2
= dvdx
* dvdx
+ dvdy
* dvdy
;
202 GLfloat rho2
= r1
+ r2
;
203 /* return log base 2 of rho */
204 return log(rho2
) * 1.442695 * 0.5; /* 1.442695 = 1/log(2) */
211 * Fill in the samples[] array with the (x,y) subpixel positions of
212 * xSamples * ySamples sample positions.
213 * Note that the four corner samples are put into the first four
214 * positions of the array. This allows us to optimize for the common
215 * case of all samples being inside the polygon.
218 make_sample_table(GLint xSamples
, GLint ySamples
, GLfloat samples
[][2])
220 const GLfloat dx
= 1.0F
/ (GLfloat
) xSamples
;
221 const GLfloat dy
= 1.0F
/ (GLfloat
) ySamples
;
226 for (x
= 0; x
< xSamples
; x
++) {
227 for (y
= 0; y
< ySamples
; y
++) {
229 if (x
== 0 && y
== 0) {
233 else if (x
== xSamples
- 1 && y
== 0) {
237 else if (x
== 0 && y
== ySamples
- 1) {
241 else if (x
== xSamples
- 1 && y
== ySamples
- 1) {
248 samples
[j
][0] = x
* dx
+ 0.5 * dx
;
249 samples
[j
][1] = y
* dy
+ 0.5 * dy
;
257 * Compute how much of the given pixel's area is inside the rectangle
258 * defined by vertices v0, v1, v2, v3.
259 * Vertices MUST be specified in counter-clockwise order.
260 * Return: coverage in [0, 1].
263 compute_coveragef(const struct LineInfo
*info
,
264 GLint winx
, GLint winy
)
266 static GLfloat samples
[SUB_PIXEL
* SUB_PIXEL
][2];
267 static GLboolean haveSamples
= GL_FALSE
;
268 const GLfloat x
= (GLfloat
) winx
;
269 const GLfloat y
= (GLfloat
) winy
;
271 GLfloat insideCount
= SUB_PIXEL
* SUB_PIXEL
;
274 make_sample_table(SUB_PIXEL
, SUB_PIXEL
, samples
);
275 haveSamples
= GL_TRUE
;
280 const GLfloat area
= dx0
* dy1
- dx1
* dy0
;
285 for (i
= 0; i
< stop
; i
++) {
286 const GLfloat sx
= x
+ samples
[i
][0];
287 const GLfloat sy
= y
+ samples
[i
][1];
288 const GLfloat fx0
= sx
- info
->qx0
;
289 const GLfloat fy0
= sy
- info
->qy0
;
290 const GLfloat fx1
= sx
- info
->qx1
;
291 const GLfloat fy1
= sy
- info
->qy1
;
292 const GLfloat fx2
= sx
- info
->qx2
;
293 const GLfloat fy2
= sy
- info
->qy2
;
294 const GLfloat fx3
= sx
- info
->qx3
;
295 const GLfloat fy3
= sy
- info
->qy3
;
296 /* cross product determines if sample is inside or outside each edge */
297 GLfloat cross0
= (info
->ex0
* fy0
- info
->ey0
* fx0
);
298 GLfloat cross1
= (info
->ex1
* fy1
- info
->ey1
* fx1
);
299 GLfloat cross2
= (info
->ex2
* fy2
- info
->ey2
* fx2
);
300 GLfloat cross3
= (info
->ex3
* fy3
- info
->ey3
* fx3
);
301 /* Check if the sample is exactly on an edge. If so, let cross be a
302 * positive or negative value depending on the direction of the edge.
305 cross0
= info
->ex0
+ info
->ey0
;
307 cross1
= info
->ex1
+ info
->ey1
;
309 cross2
= info
->ex2
+ info
->ey2
;
311 cross3
= info
->ex3
+ info
->ey3
;
312 if (cross0
< 0.0F
|| cross1
< 0.0F
|| cross2
< 0.0F
|| cross3
< 0.0F
) {
313 /* point is outside quadrilateral */
315 stop
= SUB_PIXEL
* SUB_PIXEL
;
321 return insideCount
* (1.0F
/ (SUB_PIXEL
* SUB_PIXEL
));
326 typedef void (*plot_func
)(GLcontext
*ctx
, const struct LineInfo
*line
,
327 struct pixel_buffer
*pb
, int ix
, int iy
);
331 * Draw an AA line segment (called many times per line when stippling)
334 segment(GLcontext
*ctx
,
335 struct LineInfo
*line
,
337 struct pixel_buffer
*pb
,
338 GLfloat t0
, GLfloat t1
)
340 const GLfloat absDx
= (line
->dx
< 0.0F
) ? -line
->dx
: line
->dx
;
341 const GLfloat absDy
= (line
->dy
< 0.0F
) ? -line
->dy
: line
->dy
;
342 /* compute the actual segment's endpoints */
343 const GLfloat x0
= line
->x0
+ t0
* line
->dx
;
344 const GLfloat y0
= line
->y0
+ t0
* line
->dy
;
345 const GLfloat x1
= line
->x0
+ t1
* line
->dx
;
346 const GLfloat y1
= line
->y0
+ t1
* line
->dy
;
348 /* compute vertices of the line-aligned quadrilateral */
349 line
->qx0
= x0
- line
->yAdj
;
350 line
->qy0
= y0
+ line
->xAdj
;
351 line
->qx1
= x0
+ line
->yAdj
;
352 line
->qy1
= y0
- line
->xAdj
;
353 line
->qx2
= x1
+ line
->yAdj
;
354 line
->qy2
= y1
- line
->xAdj
;
355 line
->qx3
= x1
- line
->yAdj
;
356 line
->qy3
= y1
+ line
->xAdj
;
357 /* compute the quad's edge vectors (for coverage calc) */
358 line
->ex0
= line
->qx1
- line
->qx0
;
359 line
->ey0
= line
->qy1
- line
->qy0
;
360 line
->ex1
= line
->qx2
- line
->qx1
;
361 line
->ey1
= line
->qy2
- line
->qy1
;
362 line
->ex2
= line
->qx3
- line
->qx2
;
363 line
->ey2
= line
->qy3
- line
->qy2
;
364 line
->ex3
= line
->qx0
- line
->qx3
;
365 line
->ey3
= line
->qy0
- line
->qy3
;
369 GLfloat dydx
= line
->dy
/ line
->dx
;
370 GLfloat xLeft
, xRight
, yBot
, yTop
;
373 xLeft
= x0
- line
->halfWidth
;
374 xRight
= x1
+ line
->halfWidth
;
375 if (line
->dy
>= 0.0) {
376 yBot
= y0
- 3.0 * line
->halfWidth
;
377 yTop
= y0
+ line
->halfWidth
;
380 yBot
= y0
- line
->halfWidth
;
381 yTop
= y0
+ 3.0 * line
->halfWidth
;
385 xLeft
= x1
- line
->halfWidth
;
386 xRight
= x0
+ line
->halfWidth
;
387 if (line
->dy
<= 0.0) {
388 yBot
= y1
- 3.0 * line
->halfWidth
;
389 yTop
= y1
+ line
->halfWidth
;
392 yBot
= y1
- line
->halfWidth
;
393 yTop
= y1
+ 3.0 * line
->halfWidth
;
397 /* scan along the line, left-to-right */
398 ixRight
= (GLint
) (xRight
+ 1.0F
);
400 /*printf("avg span height: %g\n", yTop - yBot);*/
401 for (ix
= (GLint
) xLeft
; ix
< ixRight
; ix
++) {
402 const GLint iyBot
= (GLint
) yBot
;
403 const GLint iyTop
= (GLint
) (yTop
+ 1.0F
);
405 /* scan across the line, bottom-to-top */
406 for (iy
= iyBot
; iy
< iyTop
; iy
++) {
407 (*plot
)(ctx
, line
, pb
, ix
, iy
);
415 GLfloat dxdy
= line
->dx
/ line
->dy
;
416 GLfloat yBot
, yTop
, xLeft
, xRight
;
419 yBot
= y0
- line
->halfWidth
;
420 yTop
= y1
+ line
->halfWidth
;
421 if (line
->dx
>= 0.0) {
422 xLeft
= x0
- 3.0 * line
->halfWidth
;
423 xRight
= x0
+ line
->halfWidth
;
426 xLeft
= x0
- line
->halfWidth
;
427 xRight
= x0
+ 3.0 * line
->halfWidth
;
431 yBot
= y1
- line
->halfWidth
;
432 yTop
= y0
+ line
->halfWidth
;
433 if (line
->dx
<= 0.0) {
434 xLeft
= x1
- 3.0 * line
->halfWidth
;
435 xRight
= x1
+ line
->halfWidth
;
438 xLeft
= x1
- line
->halfWidth
;
439 xRight
= x1
+ 3.0 * line
->halfWidth
;
443 /* scan along the line, bottom-to-top */
444 iyTop
= (GLint
) (yTop
+ 1.0F
);
446 /*printf("avg span width: %g\n", xRight - xLeft);*/
447 for (iy
= (GLint
) yBot
; iy
< iyTop
; iy
++) {
448 const GLint ixLeft
= (GLint
) xLeft
;
449 const GLint ixRight
= (GLint
) (xRight
+ 1.0F
);
451 /* scan across the line, left-to-right */
452 for (ix
= ixLeft
; ix
< ixRight
; ix
++) {
453 (*plot
)(ctx
, line
, pb
, ix
, iy
);
462 #define NAME(x) aa_ci_##x
466 #include "s_aalinetemp.h"
469 #define NAME(x) aa_rgba_##x
473 #include "s_aalinetemp.h"
476 #define NAME(x) aa_tex_rgba_##x
481 #include "s_aalinetemp.h"
484 #define NAME(x) aa_multitex_rgba_##x
489 #include "s_aalinetemp.h"
494 _swrast_choose_aa_line_function(GLcontext
*ctx
)
496 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
498 ASSERT(ctx
->Line
.SmoothFlag
);
500 if (ctx
->Visual
.rgbMode
) {
502 if (ctx
->Texture
._ReallyEnabled
) {
503 if (swrast
->_MultiTextureEnabled
504 || ctx
->Light
.Model
.ColorControl
==GL_SEPARATE_SPECULAR_COLOR
505 || ctx
->Fog
.ColorSumEnabled
)
507 swrast
->Line
= aa_multitex_rgba_line
;
509 swrast
->Line
= aa_tex_rgba_line
;
512 swrast
->Line
= aa_rgba_line
;
517 swrast
->Line
= aa_ci_line
;