2 * Mesa 3-D graphics library
4 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included
14 * in all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
26 #include "main/glheader.h"
27 #include "main/imports.h"
28 #include "main/macros.h"
29 #include "main/mtypes.h"
30 #include "main/teximage.h"
31 #include "swrast/s_aaline.h"
32 #include "swrast/s_context.h"
33 #include "swrast/s_span.h"
34 #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 */
63 /* DO_RGBA - always enabled */
64 GLfloat rPlane
[4], gPlane
[4], bPlane
[4], aPlane
[4];
67 GLfloat attrPlane
[VARYING_SLOT_MAX
][4][4];
68 GLfloat lambda
[VARYING_SLOT_MAX
];
69 GLfloat texWidth
[VARYING_SLOT_MAX
];
70 GLfloat texHeight
[VARYING_SLOT_MAX
];
78 * Compute the equation of a plane used to interpolate line fragment data
79 * such as color, Z, texture coords, etc.
80 * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
81 * z0, and z1 are the end point values to interpolate.
82 * Output: plane - the plane equation.
84 * Note: we don't really have enough parameters to specify a plane.
85 * We take the endpoints of the line and compute a plane such that
86 * the cross product of the line vector and the plane normal is
87 * parallel to the projection plane.
90 compute_plane(GLfloat x0
, GLfloat y0
, GLfloat x1
, GLfloat y1
,
91 GLfloat z0
, GLfloat z1
, GLfloat plane
[4])
95 const GLfloat px
= x1
- x0
;
96 const GLfloat py
= y1
- y0
;
97 const GLfloat pz
= z1
- z0
;
98 const GLfloat qx
= -py
;
99 const GLfloat qy
= px
;
100 const GLfloat qz
= 0;
101 const GLfloat a
= py
* qz
- pz
* qy
;
102 const GLfloat b
= pz
* qx
- px
* qz
;
103 const GLfloat c
= px
* qy
- py
* qx
;
104 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
111 const GLfloat px
= x1
- x0
;
112 const GLfloat py
= y1
- y0
;
113 const GLfloat pz
= z0
- z1
;
114 const GLfloat a
= pz
* px
;
115 const GLfloat b
= pz
* py
;
116 const GLfloat c
= px
* px
+ py
* py
;
117 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
118 if (a
== 0.0 && b
== 0.0 && c
== 0.0 && d
== 0.0) {
135 constant_plane(GLfloat value
, GLfloat plane
[4])
144 static inline GLfloat
145 solve_plane(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
147 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
151 #define SOLVE_PLANE(X, Y, PLANE) \
152 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
156 * Return 1 / solve_plane().
158 static inline GLfloat
159 solve_plane_recip(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
161 const GLfloat denom
= plane
[3] + plane
[0] * x
+ plane
[1] * y
;
165 return -plane
[2] / denom
;
170 * Solve plane and return clamped GLchan value.
173 solve_plane_chan(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
175 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
176 #if CHAN_TYPE == GL_FLOAT
177 return CLAMP(z
, 0.0F
, CHAN_MAXF
);
181 else if (z
> CHAN_MAX
)
183 return (GLchan
) IROUND_POS(z
);
189 * Compute mipmap level of detail.
191 static inline GLfloat
192 compute_lambda(const GLfloat sPlane
[4], const GLfloat tPlane
[4],
193 GLfloat invQ
, GLfloat width
, GLfloat height
)
195 GLfloat dudx
= sPlane
[0] / sPlane
[2] * invQ
* width
;
196 GLfloat dudy
= sPlane
[1] / sPlane
[2] * invQ
* width
;
197 GLfloat dvdx
= tPlane
[0] / tPlane
[2] * invQ
* height
;
198 GLfloat dvdy
= tPlane
[1] / tPlane
[2] * invQ
* height
;
199 GLfloat r1
= dudx
* dudx
+ dudy
* dudy
;
200 GLfloat r2
= dvdx
* dvdx
+ dvdy
* dvdy
;
201 GLfloat rho2
= r1
+ r2
;
202 /* return log base 2 of rho */
206 return (GLfloat
) (LOGF(rho2
) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
213 * Fill in the samples[] array with the (x,y) subpixel positions of
214 * xSamples * ySamples sample positions.
215 * Note that the four corner samples are put into the first four
216 * positions of the array. This allows us to optimize for the common
217 * case of all samples being inside the polygon.
220 make_sample_table(GLint xSamples
, GLint ySamples
, GLfloat samples
[][2])
222 const GLfloat dx
= 1.0F
/ (GLfloat
) xSamples
;
223 const GLfloat dy
= 1.0F
/ (GLfloat
) ySamples
;
228 for (x
= 0; x
< xSamples
; x
++) {
229 for (y
= 0; y
< ySamples
; y
++) {
231 if (x
== 0 && y
== 0) {
235 else if (x
== xSamples
- 1 && y
== 0) {
239 else if (x
== 0 && y
== ySamples
- 1) {
243 else if (x
== xSamples
- 1 && y
== ySamples
- 1) {
250 samples
[j
][0] = x
* dx
+ 0.5F
* dx
;
251 samples
[j
][1] = y
* dy
+ 0.5F
* dy
;
259 * Compute how much of the given pixel's area is inside the rectangle
260 * defined by vertices v0, v1, v2, v3.
261 * Vertices MUST be specified in counter-clockwise order.
262 * Return: coverage in [0, 1].
265 compute_coveragef(const struct LineInfo
*info
,
266 GLint winx
, GLint winy
)
268 static GLfloat samples
[SUB_PIXEL
* SUB_PIXEL
][2];
269 static GLboolean haveSamples
= GL_FALSE
;
270 const GLfloat x
= (GLfloat
) winx
;
271 const GLfloat y
= (GLfloat
) winy
;
273 GLfloat insideCount
= SUB_PIXEL
* SUB_PIXEL
;
276 make_sample_table(SUB_PIXEL
, SUB_PIXEL
, samples
);
277 haveSamples
= GL_TRUE
;
282 const GLfloat area
= dx0
* dy1
- dx1
* dy0
;
287 for (i
= 0; i
< stop
; i
++) {
288 const GLfloat sx
= x
+ samples
[i
][0];
289 const GLfloat sy
= y
+ samples
[i
][1];
290 const GLfloat fx0
= sx
- info
->qx0
;
291 const GLfloat fy0
= sy
- info
->qy0
;
292 const GLfloat fx1
= sx
- info
->qx1
;
293 const GLfloat fy1
= sy
- info
->qy1
;
294 const GLfloat fx2
= sx
- info
->qx2
;
295 const GLfloat fy2
= sy
- info
->qy2
;
296 const GLfloat fx3
= sx
- info
->qx3
;
297 const GLfloat fy3
= sy
- info
->qy3
;
298 /* cross product determines if sample is inside or outside each edge */
299 GLfloat cross0
= (info
->ex0
* fy0
- info
->ey0
* fx0
);
300 GLfloat cross1
= (info
->ex1
* fy1
- info
->ey1
* fx1
);
301 GLfloat cross2
= (info
->ex2
* fy2
- info
->ey2
* fx2
);
302 GLfloat cross3
= (info
->ex3
* fy3
- info
->ey3
* fx3
);
303 /* Check if the sample is exactly on an edge. If so, let cross be a
304 * positive or negative value depending on the direction of the edge.
307 cross0
= info
->ex0
+ info
->ey0
;
309 cross1
= info
->ex1
+ info
->ey1
;
311 cross2
= info
->ex2
+ info
->ey2
;
313 cross3
= info
->ex3
+ info
->ey3
;
314 if (cross0
< 0.0F
|| cross1
< 0.0F
|| cross2
< 0.0F
|| cross3
< 0.0F
) {
315 /* point is outside quadrilateral */
317 stop
= SUB_PIXEL
* SUB_PIXEL
;
323 return insideCount
* (1.0F
/ (SUB_PIXEL
* SUB_PIXEL
));
327 typedef void (*plot_func
)(struct gl_context
*ctx
, struct LineInfo
*line
,
333 * Draw an AA line segment (called many times per line when stippling)
336 segment(struct gl_context
*ctx
,
337 struct LineInfo
*line
,
339 GLfloat t0
, GLfloat t1
)
341 const GLfloat absDx
= (line
->dx
< 0.0F
) ? -line
->dx
: line
->dx
;
342 const GLfloat absDy
= (line
->dy
< 0.0F
) ? -line
->dy
: line
->dy
;
343 /* compute the actual segment's endpoints */
344 const GLfloat x0
= line
->x0
+ t0
* line
->dx
;
345 const GLfloat y0
= line
->y0
+ t0
* line
->dy
;
346 const GLfloat x1
= line
->x0
+ t1
* line
->dx
;
347 const GLfloat y1
= line
->y0
+ t1
* line
->dy
;
349 /* compute vertices of the line-aligned quadrilateral */
350 line
->qx0
= x0
- line
->yAdj
;
351 line
->qy0
= y0
+ line
->xAdj
;
352 line
->qx1
= x0
+ line
->yAdj
;
353 line
->qy1
= y0
- line
->xAdj
;
354 line
->qx2
= x1
+ line
->yAdj
;
355 line
->qy2
= y1
- line
->xAdj
;
356 line
->qx3
= x1
- line
->yAdj
;
357 line
->qy3
= y1
+ line
->xAdj
;
358 /* compute the quad's edge vectors (for coverage calc) */
359 line
->ex0
= line
->qx1
- line
->qx0
;
360 line
->ey0
= line
->qy1
- line
->qy0
;
361 line
->ex1
= line
->qx2
- line
->qx1
;
362 line
->ey1
= line
->qy2
- line
->qy1
;
363 line
->ex2
= line
->qx3
- line
->qx2
;
364 line
->ey2
= line
->qy3
- line
->qy2
;
365 line
->ex3
= line
->qx0
- line
->qx3
;
366 line
->ey3
= line
->qy0
- line
->qy3
;
370 GLfloat dydx
= line
->dy
/ line
->dx
;
371 GLfloat xLeft
, xRight
, yBot
, yTop
;
374 xLeft
= x0
- line
->halfWidth
;
375 xRight
= x1
+ line
->halfWidth
;
376 if (line
->dy
>= 0.0) {
377 yBot
= y0
- 3.0F
* line
->halfWidth
;
378 yTop
= y0
+ line
->halfWidth
;
381 yBot
= y0
- line
->halfWidth
;
382 yTop
= y0
+ 3.0F
* line
->halfWidth
;
386 xLeft
= x1
- line
->halfWidth
;
387 xRight
= x0
+ line
->halfWidth
;
388 if (line
->dy
<= 0.0) {
389 yBot
= y1
- 3.0F
* line
->halfWidth
;
390 yTop
= y1
+ line
->halfWidth
;
393 yBot
= y1
- line
->halfWidth
;
394 yTop
= y1
+ 3.0F
* line
->halfWidth
;
398 /* scan along the line, left-to-right */
399 ixRight
= (GLint
) (xRight
+ 1.0F
);
401 /*printf("avg span height: %g\n", yTop - yBot);*/
402 for (ix
= (GLint
) xLeft
; ix
< ixRight
; ix
++) {
403 const GLint iyBot
= (GLint
) yBot
;
404 const GLint iyTop
= (GLint
) (yTop
+ 1.0F
);
406 /* scan across the line, bottom-to-top */
407 for (iy
= iyBot
; iy
< iyTop
; iy
++) {
408 (*plot
)(ctx
, line
, ix
, iy
);
416 GLfloat dxdy
= line
->dx
/ line
->dy
;
417 GLfloat yBot
, yTop
, xLeft
, xRight
;
420 yBot
= y0
- line
->halfWidth
;
421 yTop
= y1
+ line
->halfWidth
;
422 if (line
->dx
>= 0.0) {
423 xLeft
= x0
- 3.0F
* line
->halfWidth
;
424 xRight
= x0
+ line
->halfWidth
;
427 xLeft
= x0
- line
->halfWidth
;
428 xRight
= x0
+ 3.0F
* line
->halfWidth
;
432 yBot
= y1
- line
->halfWidth
;
433 yTop
= y0
+ line
->halfWidth
;
434 if (line
->dx
<= 0.0) {
435 xLeft
= x1
- 3.0F
* line
->halfWidth
;
436 xRight
= x1
+ line
->halfWidth
;
439 xLeft
= x1
- line
->halfWidth
;
440 xRight
= x1
+ 3.0F
* line
->halfWidth
;
444 /* scan along the line, bottom-to-top */
445 iyTop
= (GLint
) (yTop
+ 1.0F
);
447 /*printf("avg span width: %g\n", xRight - xLeft);*/
448 for (iy
= (GLint
) yBot
; iy
< iyTop
; iy
++) {
449 const GLint ixLeft
= (GLint
) xLeft
;
450 const GLint ixRight
= (GLint
) (xRight
+ 1.0F
);
452 /* scan across the line, left-to-right */
453 for (ix
= ixLeft
; ix
< ixRight
; ix
++) {
454 (*plot
)(ctx
, line
, ix
, iy
);
463 #define NAME(x) aa_rgba_##x
465 #include "s_aalinetemp.h"
468 #define NAME(x) aa_general_rgba_##x
471 #include "s_aalinetemp.h"
476 _swrast_choose_aa_line_function(struct gl_context
*ctx
)
478 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
480 ASSERT(ctx
->Line
.SmoothFlag
);
482 if (ctx
->Texture
._EnabledCoordUnits
!= 0
483 || _swrast_use_fragment_program(ctx
)
484 || (ctx
->Light
.Enabled
&&
485 ctx
->Light
.Model
.ColorControl
== GL_SEPARATE_SPECULAR_COLOR
)
486 || ctx
->Fog
.ColorSumEnabled
487 || swrast
->_FogEnabled
) {
488 swrast
->Line
= aa_general_rgba_line
;
491 swrast
->Line
= aa_rgba_line
;