/*
* Mesa 3-D graphics library
* Version: 7.0.3
*
* 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
* BRIAN PAUL 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.
*/
/*
* Antialiased Triangle Rasterizer Template
*
* This file is #include'd to generate custom AA triangle rasterizers.
* NOTE: this code hasn't been optimized yet. That'll come after it
* works correctly.
*
* The following macros may be defined to indicate what auxillary information
* must be copmuted across the triangle:
* DO_Z - if defined, compute Z values
* DO_ATTRIBS - if defined, compute texcoords, varying, etc.
*/
/*void triangle( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv )*/
{
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLfloat *p0 = v0->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *p1 = v1->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *p2 = v2->attrib[FRAG_ATTRIB_WPOS];
const SWvertex *vMin, *vMid, *vMax;
GLint iyMin, iyMax;
GLfloat yMin, yMax;
GLboolean ltor;
GLfloat majDx, majDy; /* major (i.e. long) edge dx and dy */
SWspan span;
#ifdef DO_Z
GLfloat zPlane[4];
#endif
GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
#if defined(DO_ATTRIBS)
GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
GLfloat wPlane[4]; /* win[3] */
#endif
GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceCullSign;
(void) swrast;
INIT_SPAN(span, GL_POLYGON);
span.arrayMask = SPAN_COVERAGE;
/* determine bottom to top order of vertices */
{
GLfloat y0 = v0->attrib[FRAG_ATTRIB_WPOS][1];
GLfloat y1 = v1->attrib[FRAG_ATTRIB_WPOS][1];
GLfloat y2 = v2->attrib[FRAG_ATTRIB_WPOS][1];
if (y0 <= y1) {
if (y1 <= y2) {
vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */
}
else if (y2 <= y0) {
vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */
}
else {
vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */
}
}
else {
if (y0 <= y2) {
vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */
}
else if (y2 <= y1) {
vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */
}
else {
vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */
}
}
}
majDx = vMax->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
majDy = vMax->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
/* front/back-face determination and cullling */
{
const GLfloat botDx = vMid->attrib[FRAG_ATTRIB_WPOS][0] - vMin->attrib[FRAG_ATTRIB_WPOS][0];
const GLfloat botDy = vMid->attrib[FRAG_ATTRIB_WPOS][1] - vMin->attrib[FRAG_ATTRIB_WPOS][1];
const GLfloat area = majDx * botDy - botDx * majDy;
/* Do backface culling */
if (area * bf < 0 || area == 0 || IS_INF_OR_NAN(area))
return;
ltor = (GLboolean) (area < 0.0F);
span.facing = area * swrast->_BackfaceSign > 0.0F;
}
/* Plane equation setup:
* We evaluate plane equations at window (x,y) coordinates in order
* to compute color, Z, fog, texcoords, etc. This isn't terribly
* efficient but it's easy and reliable.
*/
#ifdef DO_Z
compute_plane(p0, p1, p2, p0[2], p1[2], p2[2], zPlane);
span.arrayMask |= SPAN_Z;
#endif
if (ctx->Light.ShadeModel == GL_SMOOTH) {
compute_plane(p0, p1, p2, v0->color[RCOMP], v1->color[RCOMP], v2->color[RCOMP], rPlane);
compute_plane(p0, p1, p2, v0->color[GCOMP], v1->color[GCOMP], v2->color[GCOMP], gPlane);
compute_plane(p0, p1, p2, v0->color[BCOMP], v1->color[BCOMP], v2->color[BCOMP], bPlane);
compute_plane(p0, p1, p2, v0->color[ACOMP], v1->color[ACOMP], v2->color[ACOMP], aPlane);
}
else {
constant_plane(v2->color[RCOMP], rPlane);
constant_plane(v2->color[GCOMP], gPlane);
constant_plane(v2->color[BCOMP], bPlane);
constant_plane(v2->color[ACOMP], aPlane);
}
span.arrayMask |= SPAN_RGBA;
#if defined(DO_ATTRIBS)
{
const GLfloat invW0 = v0->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat invW1 = v1->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat invW2 = v2->attrib[FRAG_ATTRIB_WPOS][3];
compute_plane(p0, p1, p2, invW0, invW1, invW2, wPlane);
span.attrStepX[FRAG_ATTRIB_WPOS][3] = plane_dx(wPlane);
span.attrStepY[FRAG_ATTRIB_WPOS][3] = plane_dy(wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
if (swrast->_InterpMode[attr] == GL_FLAT) {
for (c = 0; c < 4; c++) {
constant_plane(v2->attrib[attr][c] * invW2, attrPlane[attr][c]);
}
}
else {
for (c = 0; c < 4; c++) {
const GLfloat a0 = v0->attrib[attr][c] * invW0;
const GLfloat a1 = v1->attrib[attr][c] * invW1;
const GLfloat a2 = v2->attrib[attr][c] * invW2;
compute_plane(p0, p1, p2, a0, a1, a2, attrPlane[attr][c]);
}
}
for (c = 0; c < 4; c++) {
span.attrStepX[attr][c] = plane_dx(attrPlane[attr][c]);
span.attrStepY[attr][c] = plane_dy(attrPlane[attr][c]);
}
ATTRIB_LOOP_END
}
#endif
/* Begin bottom-to-top scan over the triangle.
* The long edge will either be on the left or right side of the
* triangle. We always scan from the long edge toward the shorter
* edges, stopping when we find that coverage = 0. If the long edge
* is on the left we scan left-to-right. Else, we scan right-to-left.
*/
yMin = vMin->attrib[FRAG_ATTRIB_WPOS][1];
yMax = vMax->attrib[FRAG_ATTRIB_WPOS][1];
iyMin = (GLint) yMin;
iyMax = (GLint) yMax + 1;
if (ltor) {
/* scan left to right */
const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
const GLfloat dxdy = majDx / majDy;
const GLfloat xAdj = dxdy < 0.0F ? -dxdy : 0.0F;
GLfloat x = pMin[0] - (yMin - iyMin) * dxdy;
GLint iy;
for (iy = iyMin; iy < iyMax; iy++, x += dxdy) {
GLint ix, startX = (GLint) (x - xAdj);
GLuint count;
GLfloat coverage = 0.0F;
/* skip over fragments with zero coverage */
while (startX < MAX_WIDTH) {
coverage = compute_coveragef(pMin, pMid, pMax, startX, iy);
if (coverage > 0.0F)
break;
startX++;
}
/* enter interior of triangle */
ix = startX;
#if defined(DO_ATTRIBS)
/* compute attributes at left-most fragment */
span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 0.5F, iy + 0.5F, wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
span.attrStart[attr][c] = solve_plane(ix + 0.5F, iy + 0.5F, attrPlane[attr][c]);
}
ATTRIB_LOOP_END
#endif
count = 0;
while (coverage > 0.0F) {
/* (cx,cy) = center of fragment */
const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
SWspanarrays *array = span.array;
array->coverage[count] = coverage;
#ifdef DO_Z
array->z[count] = (GLuint) solve_plane(cx, cy, zPlane);
#endif
array->rgba[count][RCOMP] = solve_plane_chan(cx, cy, rPlane);
array->rgba[count][GCOMP] = solve_plane_chan(cx, cy, gPlane);
array->rgba[count][BCOMP] = solve_plane_chan(cx, cy, bPlane);
array->rgba[count][ACOMP] = solve_plane_chan(cx, cy, aPlane);
ix++;
count++;
coverage = compute_coveragef(pMin, pMid, pMax, ix, iy);
}
if (ix <= startX)
continue;
span.x = startX;
span.y = iy;
span.end = (GLuint) ix - (GLuint) startX;
_swrast_write_rgba_span(ctx, &span);
}
}
else {
/* scan right to left */
const GLfloat *pMin = vMin->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMid = vMid->attrib[FRAG_ATTRIB_WPOS];
const GLfloat *pMax = vMax->attrib[FRAG_ATTRIB_WPOS];
const GLfloat dxdy = majDx / majDy;
const GLfloat xAdj = dxdy > 0 ? dxdy : 0.0F;
GLfloat x = pMin[0] - (yMin - iyMin) * dxdy;
GLint iy;
for (iy = iyMin; iy < iyMax; iy++, x += dxdy) {
GLint ix, left, startX = (GLint) (x + xAdj);
GLuint count, n;
GLfloat coverage = 0.0F;
/* make sure we're not past the window edge */
if (startX >= ctx->DrawBuffer->_Xmax) {
startX = ctx->DrawBuffer->_Xmax - 1;
}
/* skip fragments with zero coverage */
while (startX > 0) {
coverage = compute_coveragef(pMin, pMax, pMid, startX, iy);
if (coverage > 0.0F)
break;
startX--;
}
/* enter interior of triangle */
ix = startX;
count = 0;
while (coverage > 0.0F) {
/* (cx,cy) = center of fragment */
const GLfloat cx = ix + 0.5F, cy = iy + 0.5F;
SWspanarrays *array = span.array;
ASSERT(ix >= 0);
array->coverage[ix] = coverage;
#ifdef DO_Z
array->z[ix] = (GLuint) solve_plane(cx, cy, zPlane);
#endif
array->rgba[ix][RCOMP] = solve_plane_chan(cx, cy, rPlane);
array->rgba[ix][GCOMP] = solve_plane_chan(cx, cy, gPlane);
array->rgba[ix][BCOMP] = solve_plane_chan(cx, cy, bPlane);
array->rgba[ix][ACOMP] = solve_plane_chan(cx, cy, aPlane);
ix--;
count++;
coverage = compute_coveragef(pMin, pMax, pMid, ix, iy);
}
#if defined(DO_ATTRIBS)
/* compute attributes at left-most fragment */
span.attrStart[FRAG_ATTRIB_WPOS][3] = solve_plane(ix + 1.5F, iy + 0.5F, wPlane);
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
span.attrStart[attr][c] = solve_plane(ix + 1.5F, iy + 0.5F, attrPlane[attr][c]);
}
ATTRIB_LOOP_END
#endif
if (startX <= ix)
continue;
n = (GLuint) startX - (GLuint) ix;
left = ix + 1;
/* shift all values to the left */
/* XXX this is temporary */
{
SWspanarrays *array = span.array;
GLint j;
for (j = 0; j < (GLint) n; j++) {
array->coverage[j] = array->coverage[j + left];
COPY_CHAN4(array->rgba[j], array->rgba[j + left]);
#ifdef DO_Z
array->z[j] = array->z[j + left];
#endif
}
}
span.x = left;
span.y = iy;
span.end = n;
_swrast_write_rgba_span(ctx, &span);
}
}
}
#undef DO_Z
#undef DO_ATTRIBS
#undef DO_OCCLUSION_TEST