2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
21 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
22 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23 * OTHER DEALINGS IN THE SOFTWARE.
27 #include "main/glheader.h"
28 #include "main/imports.h"
29 #include "main/macros.h"
30 #include "main/mtypes.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;