/*
* Mesa 3-D graphics library
*
* Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "c99_math.h"
#include "main/glheader.h"
#include "main/imports.h"
#include "main/macros.h"
#include "main/mtypes.h"
#include "main/teximage.h"
#include "swrast/s_aaline.h"
#include "swrast/s_context.h"
#include "swrast/s_span.h"
#include "swrast/swrast.h"
#define SUB_PIXEL 4
/*
* Info about the AA line we're rendering
*/
struct LineInfo
{
GLfloat x0, y0; /* start */
GLfloat x1, y1; /* end */
GLfloat dx, dy; /* direction vector */
GLfloat len; /* length */
GLfloat halfWidth; /* half of line width */
GLfloat xAdj, yAdj; /* X and Y adjustment for quad corners around line */
/* for coverage computation */
GLfloat qx0, qy0; /* quad vertices */
GLfloat qx1, qy1;
GLfloat qx2, qy2;
GLfloat qx3, qy3;
GLfloat ex0, ey0; /* quad edge vectors */
GLfloat ex1, ey1;
GLfloat ex2, ey2;
GLfloat ex3, ey3;
/* DO_Z */
GLfloat zPlane[4];
/* DO_RGBA - always enabled */
GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
/* DO_ATTRIBS */
GLfloat wPlane[4];
GLfloat attrPlane[VARYING_SLOT_MAX][4][4];
GLfloat lambda[VARYING_SLOT_MAX];
GLfloat texWidth[VARYING_SLOT_MAX];
GLfloat texHeight[VARYING_SLOT_MAX];
SWspan span;
};
/*
* Compute the equation of a plane used to interpolate line fragment data
* such as color, Z, texture coords, etc.
* Input: (x0, y0) and (x1,y1) are the endpoints of the line.
* z0, and z1 are the end point values to interpolate.
* Output: plane - the plane equation.
*
* Note: we don't really have enough parameters to specify a plane.
* We take the endpoints of the line and compute a plane such that
* the cross product of the line vector and the plane normal is
* parallel to the projection plane.
*/
static void
compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
GLfloat z0, GLfloat z1, GLfloat plane[4])
{
#if 0
/* original */
const GLfloat px = x1 - x0;
const GLfloat py = y1 - y0;
const GLfloat pz = z1 - z0;
const GLfloat qx = -py;
const GLfloat qy = px;
const GLfloat qz = 0;
const GLfloat a = py * qz - pz * qy;
const GLfloat b = pz * qx - px * qz;
const GLfloat c = px * qy - py * qx;
const GLfloat d = -(a * x0 + b * y0 + c * z0);
plane[0] = a;
plane[1] = b;
plane[2] = c;
plane[3] = d;
#else
/* simplified */
const GLfloat px = x1 - x0;
const GLfloat py = y1 - y0;
const GLfloat pz = z0 - z1;
const GLfloat a = pz * px;
const GLfloat b = pz * py;
const GLfloat c = px * px + py * py;
const GLfloat d = -(a * x0 + b * y0 + c * z0);
if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
plane[0] = 0.0;
plane[1] = 0.0;
plane[2] = 1.0;
plane[3] = 0.0;
}
else {
plane[0] = a;
plane[1] = b;
plane[2] = c;
plane[3] = d;
}
#endif
}
static inline void
constant_plane(GLfloat value, GLfloat plane[4])
{
plane[0] = 0.0;
plane[1] = 0.0;
plane[2] = -1.0;
plane[3] = value;
}
static inline GLfloat
solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
{
const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
return z;
}
#define SOLVE_PLANE(X, Y, PLANE) \
((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
/*
* Return 1 / solve_plane().
*/
static inline GLfloat
solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
{
const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
if (denom == 0.0)
return 0.0;
else
return -plane[2] / denom;
}
/*
* Solve plane and return clamped GLchan value.
*/
static inline GLchan
solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
{
const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
#if CHAN_TYPE == GL_FLOAT
return CLAMP(z, 0.0F, CHAN_MAXF);
#else
if (z < 0)
return 0;
else if (z > CHAN_MAX)
return CHAN_MAX;
return (GLchan) IROUND_POS(z);
#endif
}
/*
* Compute mipmap level of detail.
*/
static inline GLfloat
compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
GLfloat invQ, GLfloat width, GLfloat height)
{
GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
GLfloat r1 = dudx * dudx + dudy * dudy;
GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
GLfloat rho2 = r1 + r2;
/* return log base 2 of rho */
if (rho2 == 0.0F)
return 0.0;
else
return logf(rho2) * 1.442695f * 0.5f;/* 1.442695 = 1/log(2) */
}
/*
* Fill in the samples[] array with the (x,y) subpixel positions of
* xSamples * ySamples sample positions.
* Note that the four corner samples are put into the first four
* positions of the array. This allows us to optimize for the common
* case of all samples being inside the polygon.
*/
static void
make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
{
const GLfloat dx = 1.0F / (GLfloat) xSamples;
const GLfloat dy = 1.0F / (GLfloat) ySamples;
GLint x, y;
GLint i;
i = 4;
for (x = 0; x < xSamples; x++) {
for (y = 0; y < ySamples; y++) {
GLint j;
if (x == 0 && y == 0) {
/* lower left */
j = 0;
}
else if (x == xSamples - 1 && y == 0) {
/* lower right */
j = 1;
}
else if (x == 0 && y == ySamples - 1) {
/* upper left */
j = 2;
}
else if (x == xSamples - 1 && y == ySamples - 1) {
/* upper right */
j = 3;
}
else {
j = i++;
}
samples[j][0] = x * dx + 0.5F * dx;
samples[j][1] = y * dy + 0.5F * dy;
}
}
}
/*
* Compute how much of the given pixel's area is inside the rectangle
* defined by vertices v0, v1, v2, v3.
* Vertices MUST be specified in counter-clockwise order.
* Return: coverage in [0, 1].
*/
static GLfloat
compute_coveragef(const struct LineInfo *info,
GLint winx, GLint winy)
{
static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
static GLboolean haveSamples = GL_FALSE;
const GLfloat x = (GLfloat) winx;
const GLfloat y = (GLfloat) winy;
GLint stop = 4, i;
GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;
if (!haveSamples) {
make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
haveSamples = GL_TRUE;
}
#if 0 /*DEBUG*/
{
const GLfloat area = dx0 * dy1 - dx1 * dy0;
}
#endif
for (i = 0; i < stop; i++) {
const GLfloat sx = x + samples[i][0];
const GLfloat sy = y + samples[i][1];
const GLfloat fx0 = sx - info->qx0;
const GLfloat fy0 = sy - info->qy0;
const GLfloat fx1 = sx - info->qx1;
const GLfloat fy1 = sy - info->qy1;
const GLfloat fx2 = sx - info->qx2;
const GLfloat fy2 = sy - info->qy2;
const GLfloat fx3 = sx - info->qx3;
const GLfloat fy3 = sy - info->qy3;
/* cross product determines if sample is inside or outside each edge */
GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
/* Check if the sample is exactly on an edge. If so, let cross be a
* positive or negative value depending on the direction of the edge.
*/
if (cross0 == 0.0F)
cross0 = info->ex0 + info->ey0;
if (cross1 == 0.0F)
cross1 = info->ex1 + info->ey1;
if (cross2 == 0.0F)
cross2 = info->ex2 + info->ey2;
if (cross3 == 0.0F)
cross3 = info->ex3 + info->ey3;
if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
/* point is outside quadrilateral */
insideCount -= 1.0F;
stop = SUB_PIXEL * SUB_PIXEL;
}
}
if (stop == 4)
return 1.0F;
else
return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
}
typedef void (*plot_func)(struct gl_context *ctx, struct LineInfo *line,
int ix, int iy);
/*
* Draw an AA line segment (called many times per line when stippling)
*/
static void
segment(struct gl_context *ctx,
struct LineInfo *line,
plot_func plot,
GLfloat t0, GLfloat t1)
{
const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
/* compute the actual segment's endpoints */
const GLfloat x0 = line->x0 + t0 * line->dx;
const GLfloat y0 = line->y0 + t0 * line->dy;
const GLfloat x1 = line->x0 + t1 * line->dx;
const GLfloat y1 = line->y0 + t1 * line->dy;
/* compute vertices of the line-aligned quadrilateral */
line->qx0 = x0 - line->yAdj;
line->qy0 = y0 + line->xAdj;
line->qx1 = x0 + line->yAdj;
line->qy1 = y0 - line->xAdj;
line->qx2 = x1 + line->yAdj;
line->qy2 = y1 - line->xAdj;
line->qx3 = x1 - line->yAdj;
line->qy3 = y1 + line->xAdj;
/* compute the quad's edge vectors (for coverage calc) */
line->ex0 = line->qx1 - line->qx0;
line->ey0 = line->qy1 - line->qy0;
line->ex1 = line->qx2 - line->qx1;
line->ey1 = line->qy2 - line->qy1;
line->ex2 = line->qx3 - line->qx2;
line->ey2 = line->qy3 - line->qy2;
line->ex3 = line->qx0 - line->qx3;
line->ey3 = line->qy0 - line->qy3;
if (absDx > absDy) {
/* X-major line */
GLfloat dydx = line->dy / line->dx;
GLfloat xLeft, xRight, yBot, yTop;
GLint ix, ixRight;
if (x0 < x1) {
xLeft = x0 - line->halfWidth;
xRight = x1 + line->halfWidth;
if (line->dy >= 0.0) {
yBot = y0 - 3.0F * line->halfWidth;
yTop = y0 + line->halfWidth;
}
else {
yBot = y0 - line->halfWidth;
yTop = y0 + 3.0F * line->halfWidth;
}
}
else {
xLeft = x1 - line->halfWidth;
xRight = x0 + line->halfWidth;
if (line->dy <= 0.0) {
yBot = y1 - 3.0F * line->halfWidth;
yTop = y1 + line->halfWidth;
}
else {
yBot = y1 - line->halfWidth;
yTop = y1 + 3.0F * line->halfWidth;
}
}
/* scan along the line, left-to-right */
ixRight = (GLint) (xRight + 1.0F);
/*printf("avg span height: %g\n", yTop - yBot);*/
for (ix = (GLint) xLeft; ix < ixRight; ix++) {
const GLint iyBot = (GLint) yBot;
const GLint iyTop = (GLint) (yTop + 1.0F);
GLint iy;
/* scan across the line, bottom-to-top */
for (iy = iyBot; iy < iyTop; iy++) {
(*plot)(ctx, line, ix, iy);
}
yBot += dydx;
yTop += dydx;
}
}
else {
/* Y-major line */
GLfloat dxdy = line->dx / line->dy;
GLfloat yBot, yTop, xLeft, xRight;
GLint iy, iyTop;
if (y0 < y1) {
yBot = y0 - line->halfWidth;
yTop = y1 + line->halfWidth;
if (line->dx >= 0.0) {
xLeft = x0 - 3.0F * line->halfWidth;
xRight = x0 + line->halfWidth;
}
else {
xLeft = x0 - line->halfWidth;
xRight = x0 + 3.0F * line->halfWidth;
}
}
else {
yBot = y1 - line->halfWidth;
yTop = y0 + line->halfWidth;
if (line->dx <= 0.0) {
xLeft = x1 - 3.0F * line->halfWidth;
xRight = x1 + line->halfWidth;
}
else {
xLeft = x1 - line->halfWidth;
xRight = x1 + 3.0F * line->halfWidth;
}
}
/* scan along the line, bottom-to-top */
iyTop = (GLint) (yTop + 1.0F);
/*printf("avg span width: %g\n", xRight - xLeft);*/
for (iy = (GLint) yBot; iy < iyTop; iy++) {
const GLint ixLeft = (GLint) xLeft;
const GLint ixRight = (GLint) (xRight + 1.0F);
GLint ix;
/* scan across the line, left-to-right */
for (ix = ixLeft; ix < ixRight; ix++) {
(*plot)(ctx, line, ix, iy);
}
xLeft += dxdy;
xRight += dxdy;
}
}
}
#define NAME(x) aa_rgba_##x
#define DO_Z
#include "s_aalinetemp.h"
#define NAME(x) aa_general_rgba_##x
#define DO_Z
#define DO_ATTRIBS
#include "s_aalinetemp.h"
void
_swrast_choose_aa_line_function(struct gl_context *ctx)
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
if (ctx->Texture._EnabledCoordUnits != 0
|| _swrast_use_fragment_program(ctx)
|| (ctx->Light.Enabled &&
ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)
|| ctx->Fog.ColorSumEnabled
|| swrast->_FogEnabled) {
swrast->Line = aa_general_rgba_line;
}
else {
swrast->Line = aa_rgba_line;
}
}