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windows-server-2003/multimedia/opengl/server/soft/so_polya.c

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/*
** Copyright 1991, 1992, 1993, Silicon Graphics, Inc.
** All Rights Reserved.
**
** This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;
** the contents of this file may not be disclosed to third parties, copied or
** duplicated in any form, in whole or in part, without the prior written
** permission of Silicon Graphics, Inc.
**
** RESTRICTED RIGHTS LEGEND:
** Use, duplication or disclosure by the Government is subject to restrictions
** as set forth in subdivision (c)(1)(ii) of the Rights in Technical Data
** and Computer Software clause at DFARS 252.227-7013, and/or in similar or
** successor clauses in the FAR, DOD or NASA FAR Supplement. Unpublished -
** rights reserved under the Copyright Laws of the United States.
*/
#include "precomp.h"
#pragma hdrstop
#ifdef GL_WIN_phong_shading
#include "phong.h"
#endif //GL_WIN_phong_shading
/*
** Normal form of a line: Ax + By + C = 0. When evaluated at a point P,
** the value is zero when P is on the line. For points off the line,
** the sign of the value determines which side of the line P is on.
*/
typedef struct {
__GLfloat a, b, c;
/*
** The sign of an edge is determined by plugging the third vertex
** of the triangle into the line equation. This flag is GL_TRUE when
** the sign is positive.
*/
GLboolean edgeSign;
} __glLineEquation;
/*
** Machine state for rendering triangles.
*/
typedef struct {
__GLfloat dyAB;
__GLfloat dyBC;
__glLineEquation ab;
__glLineEquation bc;
__glLineEquation ca;
__GLfloat area;
GLint areaSign;
} __glTriangleMachine;
/*
** Plane equation coefficients. One plane equation exists for each of
** the parameters being computed across the surface of the triangle.
*/
typedef struct {
__GLfloat a, b, c, d;
} __glPlaneEquation;
/*
** Cache for some of the coverage computation constants.
*/
typedef struct {
__GLfloat dx, dy;
GLint samples;
GLint samplesSquared;
__GLfloat samplesSquaredInv;
GLboolean lastCoverageWasOne;
__GLfloat leftDelta, rightDelta;
__GLfloat bottomDelta, topDelta;
} __glCoverageStuff;
/*
** Compute the constants A, B and C for a line equation in the general
** form: Ax + By + C = 0. A given point at (x,y) can be plugged into
** the left side of the equation and yield a number which indiates whether
** or not the point is on the line. If the result is zero, then the point
** is on the line. The sign of the result determines which side of
** the line the point is on. To handle tie cases properly we need a way
** to assign a point on the edge to only one triangle. To do this, we
** look at the sign of the equation evaluated at "c". For edges whose
** sign at "c" is positive, we allow points on the edge to be in the
** triangle.
*/
static void FindLineEqation(__glLineEquation *eq, const __GLvertex *a,
const __GLvertex *b, const __GLvertex *c)
{
__GLfloat dy, dx, valueAtC;
/*
** Sort a,b so that the ordering of the verticies is consistent,
** regardless of the order given to this procedure.
*/
if (b->window.y < a->window.y) {
const __GLvertex *temp = b;
b = a;
a = temp;
} else
if ((b->window.y == a->window.y) && (b->window.x < a->window.x)) {
const __GLvertex *temp = b;
b = a;
a = temp;
}
dy = b->window.y - a->window.y;
dx = b->window.x - a->window.x;
eq->a = -dy;
eq->b = dx;
eq->c = dy * a->window.x - dx * a->window.y;
valueAtC = eq->a * c->window.x + eq->b * c->window.y + eq->c;
if (valueAtC > 0) {
eq->edgeSign = GL_TRUE;
} else {
eq->edgeSign = GL_FALSE;
}
}
/*
** Given three points in (x,y,p) find the plane equation coeffecients
** for the plane that contains the three points. First find the cross
** product of two of the vectors defined by the three points, then
** use one of the points to find "d".
*/
static void FindPlaneEquation(__glPlaneEquation *eq,
const __GLvertex *a, const __GLvertex *b,
const __GLvertex *c, __GLfloat p1,
__GLfloat p2, __GLfloat p3)
{
__GLfloat v1x, v1y, v1p;
__GLfloat v2x, v2y, v2p;
__GLfloat nx, ny, np, k;
/* find vector v1 */
v1x = b->window.x - a->window.x;
v1y = b->window.y - a->window.y;
v1p = p2 - p1;
/* find vector v2 */
v2x = c->window.x - a->window.x;
v2y = c->window.y - a->window.y;
v2p = p3 - p1;
/* find the cross product (== normal) for the plane */
nx = v1y*v2p - v1p*v2y;
ny = v1p*v2x - v1x*v2p;
np = v1x*v2y - v1y*v2x;
/*
** V dot N = k. Find k. We can use any of the three points on
** the plane, so we use a.
*/
k = a->window.x*nx + a->window.y*ny + p1*np;
/*
** Finally, setup the plane equation coeffecients. Force c to be one
** by dividing everything through by c.
*/
eq->a = nx / np;
eq->b = ny / np;
eq->c = ((__GLfloat) 1.0);
eq->d = -k / np;
}
/*
** Solve for p in the plane equation.
*/
static __GLfloat FindP(__glPlaneEquation *eq, __GLfloat x, __GLfloat y)
{
return -(eq->a * x + eq->b * y + eq->d);
}
/*
** See if a given point is on the same side of the edge as the other
** vertex in the triangle not part of this edge. When the line
** equation evaluates to zero, make points which are on lines with
** a negative edge sign (edgeSign GL_FALSE) part of the triangle.
*/
#define In(eq,x,y) \
(((eq)->a * (x) + (eq)->b * (y) + (eq)->c > 0) == (eq)->edgeSign)
/*
** Determine if the point x,y is in or out of the triangle. Evaluate
** each line equation for the point and compare the sign of the result
** with the edgeSign flag.
*/
#define Inside(tm,x,y) \
(In(&(tm)->ab, x, y) && In(&(tm)->bc, x, y) && In(&(tm)->ca, x, y))
#define FILTER_WIDTH ((__GLfloat) 1.0)
#define FILTER_HEIGHT ((__GLfloat) 1.0)
/*
** Precompute stuff that is constant for all coverage tests.
*/
static void FASTCALL ComputeCoverageStuff(__glCoverageStuff *cs, GLint samples)
{
__GLfloat dx, dy, fs = samples;
__GLfloat half = ((__GLfloat) 0.5);
cs->dx = dx = FILTER_WIDTH / fs;
cs->dy = dy = FILTER_HEIGHT / fs;
cs->leftDelta = -(FILTER_WIDTH / 2) + dx * half;
cs->rightDelta = (FILTER_WIDTH / 2) - dx * half;
cs->bottomDelta = -(FILTER_HEIGHT / 2) + dy * half;
cs->topDelta = (FILTER_HEIGHT / 2) - dy * half;
cs->samplesSquared = samples * samples;
cs->samplesSquaredInv = ((__GLfloat) 1.0) / cs->samplesSquared;
cs->samples = samples;
}
/*
** Return an estimate of the pixel coverage using sub-sampling.
*/
static __GLfloat Coverage(__glTriangleMachine *tm, __GLfloat *xs,
__GLfloat *ys, __glCoverageStuff *cs)
{
GLint xx, yy, hits, samples;
__GLfloat dx, dy, yBottom, px, py;
__GLfloat minX, minY, maxX, maxY;
hits = 0;
samples = cs->samples;
dx = cs->dx;
dy = cs->dy;
px = *xs + cs->leftDelta;
yBottom = *ys + cs->bottomDelta;
/*
** If the last coverage was one (the pixel to the left in x from us),
** then if the upper right and lower right sample positions are
** also in then this entire pixel must be in.
*/
if (cs->lastCoverageWasOne) {
__GLfloat urx, ury;
urx = *xs + cs->rightDelta;
ury = *ys + cs->topDelta;
if (Inside(tm, urx, ury) && Inside(tm, urx, yBottom)) {
return ((__GLfloat) 1.0);
}
}
/*
** Setup minimum and maximum x,y coordinates. The min and max values
** are used to find a "good" point that is actually within the
** triangle so that parameter values can be computed correctly.
*/
minX = 999999;
maxX = __glMinusOne;
minY = 999999;
maxY = __glMinusOne;
for (xx = 0; xx < samples; xx++) {
py = yBottom;
for (yy = 0; yy < samples; yy++) {
if (Inside(tm, px, py)) {
if (px < minX) minX = px;
if (px > maxX) maxX = px;
if (py < minY) minY = py;
if (py > maxY) maxY = py;
hits++;
}
py += dy;
}
px += dx;
}
if (hits) {
/*
** Return the average of the two coordinates which is guaranteed
** to be in the triangle.
*/
*xs = (minX + maxX) * ((__GLfloat) 0.5);
*ys = (minY + maxY) * ((__GLfloat) 0.5);
if (hits == cs->samplesSquared) {
/* Keep track when the last coverage was one */
cs->lastCoverageWasOne = GL_TRUE;
return ((__GLfloat) 1.0);
}
}
cs->lastCoverageWasOne = GL_FALSE;
return hits * cs->samplesSquaredInv;
}
/*
** Force f to have no more precision than the subpixel precision allows.
** Even though "f" is biased this still works and does not generate an
** overflow.
*/
#define __GL_FIX_PRECISION(f) \
((__GLfloat) ((GLint) (f * (1 << gc->constants.subpixelBits))) \
/ (1 << gc->constants.subpixelBits))
void FASTCALL __glFillAntiAliasedTriangle(__GLcontext *gc, __GLvertex *a,
__GLvertex *b, __GLvertex *c,
GLboolean ccw)
{
__glTriangleMachine tm;
__glCoverageStuff cs;
__GLcolor *ca, *cb, *cc, *flatColor;
GLint x, y, left, right, bottom, top, samples;
__glPlaneEquation qwp, zp, rp, gp, bp, ap, ezp, sp, tp;
__glPlaneEquation fp;
GLboolean rgbMode;
__GLcolorBuffer *cfb = gc->drawBuffer;
__GLfloat zero = __glZero;
__GLfloat area, ax, bx, cx, ay, by, cy;
__GLshade *sh = &gc->polygon.shader;
GLuint modeFlags = gc->polygon.shader.modeFlags;
#ifdef __GL_LINT
ccw = ccw;
#endif
/*
** Recompute the area of the triangle after constraining the incoming
** coordinates to the subpixel precision. The viewport bias gives
** more precision (typically) than the subpixel precision. Because of
** this the algorithim below can fail to reject an essentially empty
** triangle and instead fill a large area. The scan converter fill
** routines (eg polydraw.c) don't have this trouble because of the
** very nature of edge walking.
**
** NOTE: Notice that here as in other places, when the area calculation
** is done we are careful to do it as a series of subtractions followed by
** multiplications. This is done to guarantee that no overflow will
** occur (remember that the coordinates are biased by a potentially large
** number, and that multiplying two biased numbers will square the bias).
*/
ax = __GL_FIX_PRECISION(a->window.x);
bx = __GL_FIX_PRECISION(b->window.x);
cx = __GL_FIX_PRECISION(c->window.x);
ay = __GL_FIX_PRECISION(a->window.y);
by = __GL_FIX_PRECISION(b->window.y);
cy = __GL_FIX_PRECISION(c->window.y);
area = (ax - cx) * (by - cy) - (bx - cx) * (ay - cy);
if (area == zero) {
return;
}
ca = a->color;
cb = b->color;
cc = c->color;
flatColor = gc->vertex.provoking->color;
/*
** Construct plane equations for all of the parameters that are
** computed for the triangle: z, r, g, b, a, s, t, f
*/
if (modeFlags & __GL_SHADE_DEPTH_ITER) {
FindPlaneEquation(&zp, a, b, c, a->window.z, b->window.z, c->window.z);
}
if (modeFlags & __GL_SHADE_COMPUTE_FOG)
{
FindPlaneEquation(&ezp, a, b, c, a->eyeZ, b->eyeZ, c->eyeZ);
}
else if (modeFlags & __GL_SHADE_INTERP_FOG)
{
FindPlaneEquation(&fp, a, b, c, a->fog, b->fog, c->fog);
}
if (modeFlags & __GL_SHADE_TEXTURE) {
__GLfloat one = __glOne;
__GLfloat aWInv = a->window.w;
__GLfloat bWInv = b->window.w;
__GLfloat cWInv = c->window.w;
FindPlaneEquation(&qwp, a, b, c, a->texture.w * aWInv,
b->texture.w * bWInv, c->texture.w * cWInv);
FindPlaneEquation(&sp, a, b, c, a->texture.x * aWInv,
b->texture.x * bWInv, c->texture.x * cWInv);
FindPlaneEquation(&tp, a, b, c, a->texture.y * aWInv,
b->texture.y * bWInv, c->texture.y * cWInv);
}
rgbMode = gc->modes.rgbMode;
if (modeFlags & __GL_SHADE_SMOOTH) {
FindPlaneEquation(&rp, a, b, c, ca->r, cb->r, cc->r);
if (rgbMode) {
FindPlaneEquation(&gp, a, b, c, ca->g, cb->g, cc->g);
FindPlaneEquation(&bp, a, b, c, ca->b, cb->b, cc->b);
FindPlaneEquation(&ap, a, b, c, ca->a, cb->a, cc->a);
}
}
/*
** Compute general form of the line equations for each of the
** edges of the triangle.
*/
FindLineEqation(&tm.ab, a, b, c);
FindLineEqation(&tm.bc, b, c, a);
FindLineEqation(&tm.ca, c, a, b);
/* Compute bounding box of the triangle */
left = (GLint)a->window.x;
if (b->window.x < left) left = (GLint)b->window.x;
if (c->window.x < left) left = (GLint)c->window.x;
right = (GLint)a->window.x;
if (b->window.x > right) right = (GLint)b->window.x;
if (c->window.x > right) right = (GLint)c->window.x;
bottom = (GLint)a->window.y;
if (b->window.y < bottom) bottom = (GLint)b->window.y;
if (c->window.y < bottom) bottom = (GLint)c->window.y;
top = (GLint)a->window.y;
if (b->window.y > top) top = (GLint)b->window.y;
if (c->window.y > top) top = (GLint)c->window.y;
/* Bloat the bounding box when anti aliasing */
left -= (GLint)FILTER_WIDTH;
right += (GLint)FILTER_WIDTH;
bottom -= (GLint)FILTER_HEIGHT;
top += (GLint)FILTER_HEIGHT;
/* Init coverage computations */
samples = (gc->state.hints.polygonSmooth == GL_NICEST) ? 8 : 4;
ComputeCoverageStuff(&cs, samples);
/* Scan over the bounding box of the triangle */
for (y = bottom; y <= top; y++) {
cs.lastCoverageWasOne = GL_FALSE;
for (x = left; x <= right; x++) {
__GLfloat coverage;
__GLfloat xs, ys;
if (modeFlags & __GL_SHADE_STIPPLE) {
/*
** Check the window coordinate against the stipple and
** and see if the pixel can be written
*/
GLint row = y & 31;
GLint col = x & 31;
if ((gc->polygon.stipple[row] & (1<<col)) == 0) {
/*
** Stipple bit is clear. Do not render this pixel
** of the triangle.
*/
continue;
}
}
xs = x + __glHalf; /* sample point is at pixel center */
ys = y + __glHalf;
coverage = Coverage(&tm, &xs, &ys, &cs);
if (coverage != zero) {
__GLfragment frag;
/*
** Fill in fragment for rendering. First compute the color
** of the fragment.
*/
if (modeFlags & __GL_SHADE_SMOOTH) {
frag.color.r = FindP(&rp, xs, ys);
if (rgbMode) {
frag.color.g = FindP(&gp, xs, ys);
frag.color.b = FindP(&bp, xs, ys);
frag.color.a = FindP(&ap, xs, ys);
}
} else {
frag.color.r = flatColor->r;
if (rgbMode) {
frag.color.g = flatColor->g;
frag.color.b = flatColor->b;
frag.color.a = flatColor->a;
}
}
/*
** Texture the fragment.
*/
if (modeFlags & __GL_SHADE_TEXTURE) {
__GLfloat qw, s, t, rho;
qw = FindP(&qwp, xs, ys);
s = FindP(&sp, xs, ys);
t = FindP(&tp, xs, ys);
rho = (*gc->procs.calcPolygonRho)(gc, sh, s, t, qw);
#ifdef NT
if( qw == (__GLfloat) 0.0 )
s = t = (__GLfloat) 0;
else {
s /= qw;
t /= qw;
}
#else
s /= qw;
t /= qw;
#endif
(*gc->procs.texture)(gc, &frag.color, s, t, rho);
}
/*
** Fog the resulting color.
*/
if (modeFlags & __GL_SHADE_COMPUTE_FOG)
{
__GLfloat eyeZ = FindP(&ezp, xs, ys);
__glFogFragmentSlow(gc, &frag, eyeZ);
}
else if (modeFlags & __GL_SHADE_INTERP_FOG)
{
__GLfloat fog = FindP(&fp, xs, ys);
__glFogColorSlow(gc, &(frag.color), &(frag.color), fog);
}
/*
** Apply anti-aliasing effect
*/
if (rgbMode) {
frag.color.a *= coverage;
} else {
frag.color.r =
__glBuildAntiAliasIndex(frag.color.r,
coverage);
}
/*
** Finally, render the fragment.
*/
frag.x = (GLint)xs;
frag.y = (GLint)ys;
if (modeFlags & __GL_SHADE_DEPTH_ITER) {
frag.z = (__GLzValue)FindP(&zp, xs, ys);
}
(*gc->procs.store)(cfb, &frag);
}
}
}
}
#ifdef GL_WIN_phong_shading
void FASTCALL __glFillAntiAliasedPhongTriangle(__GLcontext *gc, __GLvertex *a,
__GLvertex *b, __GLvertex *c,
GLboolean ccw)
{
#if 1
__glTriangleMachine tm;
__glCoverageStuff cs;
__GLcolor *ca, *cb, *cc, *flatColor;
GLint x, y, left, right, bottom, top, samples;
__glPlaneEquation qwp, zp, rp, gp, bp, ap, ezp, sp, tp;
__glPlaneEquation exp, eyp, ewp, nxp, nyp, nzp;
__glPlaneEquation fp;
GLboolean rgbMode;
__GLcolorBuffer *cfb = gc->drawBuffer;
__GLfloat zero = __glZero;
__GLfloat area, ax, bx, cx, ay, by, cy;
__GLshade *sh = &gc->polygon.shader;
GLuint modeFlags = gc->polygon.shader.modeFlags;
__GLcoord *na, *nb, *nc, ea, eb, ec;
GLuint msm_colorMaterialChange, flags=0;
GLboolean needColor, needEye;
__GLphongShader *phong = &gc->polygon.shader.phong;
if (gc->polygon.shader.phong.face == __GL_FRONTFACE)
msm_colorMaterialChange = gc->light.back.colorMaterialChange;
else
msm_colorMaterialChange = gc->light.back.colorMaterialChange;
if ((gc->state.enables.general & __GL_COLOR_MATERIAL_ENABLE) &&
msm_colorMaterialChange && (modeFlags & __GL_SHADE_RGB))
flags |= __GL_PHONG_NEED_COLOR_XPOLATE;
//Compute Invariant color if possible
if (((!(flags & __GL_PHONG_NEED_COLOR_XPOLATE) ||
!(msm_colorMaterialChange & (__GL_MATERIAL_AMBIENT |
__GL_MATERIAL_EMISSIVE))) &&
(modeFlags & __GL_SHADE_RGB)) &&
!(flags & __GL_PHONG_NEED_EYE_XPOLATE))
{
ComputePhongInvarientRGBColor (gc);
flags |= __GL_PHONG_INV_COLOR_VALID;
}
//Store the flags
gc->polygon.shader.phong.flags |= flags;
needColor = (gc->polygon.shader.phong.flags &
__GL_PHONG_NEED_COLOR_XPOLATE);
needEye = (gc->polygon.shader.phong.flags &
__GL_PHONG_NEED_EYE_XPOLATE);
#ifdef __GL_LINT
ccw = ccw;
#endif
/*
** Recompute the area of the triangle after constraining the incoming
** coordinates to the subpixel precision. The viewport bias gives
** more precision (typically) than the subpixel precision. Because of
** this the algorithim below can fail to reject an essentially empty
** triangle and instead fill a large area. The scan converter fill
** routines (eg polydraw.c) don't have this trouble because of the
** very nature of edge walking.
**
** NOTE: Notice that here as in other places, when the area calculation
** is done we are careful to do it as a series of subtractions followed by
** multiplications. This is done to guarantee that no overflow will
** occur (remember that the coordinates are biased by a potentially large
** number, and that multiplying two biased numbers will square the bias).
*/
ax = __GL_FIX_PRECISION(a->window.x);
bx = __GL_FIX_PRECISION(b->window.x);
cx = __GL_FIX_PRECISION(c->window.x);
ay = __GL_FIX_PRECISION(a->window.y);
by = __GL_FIX_PRECISION(b->window.y);
cy = __GL_FIX_PRECISION(c->window.y);
area = (ax - cx) * (by - cy) - (bx - cx) * (ay - cy);
if (area == zero) {
return;
}
na = &a->normal;
nb = &b->normal;
nc = &c->normal;
if (needColor)
{
ca = a->color;
cb = b->color;
cc = c->color;
flatColor = gc->vertex.provoking->color;
}
if (needEye)
{
ea.x = a->eyeX; ea.y = a->eyeY; ea.z = a->eyeZ; ea.w = a->eyeW;
eb.x = b->eyeX; eb.y = b->eyeY; eb.z = b->eyeZ; eb.w = b->eyeW;
ec.x = c->eyeX; ec.y = c->eyeY; ec.z = c->eyeZ; ec.w = c->eyeW;
}
/*
** Construct plane equations for all of the parameters that are
** computed for the triangle: z, r, g, b, a, s, t, f
*/
if (modeFlags & __GL_SHADE_DEPTH_ITER)
{
FindPlaneEquation(&zp, a, b, c, a->window.z, b->window.z,
c->window.z);
}
#ifdef GL_WIN_specular_fog
if (modeFlags & __GL_SHADE_COMPUTE_FOG)
{
FindPlaneEquation(&ezp, a, b, c, a->eyeZ, b->eyeZ, c->eyeZ);
}
else if (modeFlags & __GL_SHADE_INTERP_FOG)
{
__GLfloat aFog = 1.0f, bFog = 1.0f, cFog = 1.0f;
if (gc->polygon.shader.modeFlags & __GL_SHADE_SPEC_FOG)
{
aFog = ComputeSpecValue (gc, a);
bFog = ComputeSpecValue (gc, b);
cFog = ComputeSpecValue (gc, c);
}
if (gc->polygon.shader.modeFlags & __GL_SHADE_SLOW_FOG)
{
aFog *= a->fog;
bFog *= b->fog;
cFog *= c->fog;
}
FindPlaneEquation(&fp, a, b, c, aFog, bFog, cFog);
}
#else //GL_WIN_specular_fog
if (modeFlags & __GL_SHADE_SLOW_FOG)
{
FindPlaneEquation(&ezp, a, b, c, a->eyeZ, b->eyeZ, c->eyeZ);
}
else if (modeFlags & __GL_SHADE_INTERP_FOG)
{
FindPlaneEquation(&fp, a, b, c, a->fog, b->fog, c->fog);
}
#endif //GL_WIN_specular_fog
if (modeFlags & __GL_SHADE_TEXTURE)
{
__GLfloat one = __glOne;
__GLfloat aWInv = a->window.w;
__GLfloat bWInv = b->window.w;
__GLfloat cWInv = c->window.w;
FindPlaneEquation(&qwp, a, b, c, a->texture.w * aWInv,
b->texture.w * bWInv, c->texture.w * cWInv);
FindPlaneEquation(&sp, a, b, c, a->texture.x * aWInv,
b->texture.x * bWInv, c->texture.x * cWInv);
FindPlaneEquation(&tp, a, b, c, a->texture.y * aWInv,
b->texture.y * bWInv, c->texture.y * cWInv);
}
rgbMode = gc->modes.rgbMode;
if (needColor)
{
if (modeFlags & __GL_SHADE_SMOOTH) {
FindPlaneEquation(&rp, a, b, c, ca->r, cb->r, cc->r);
if (rgbMode) {
FindPlaneEquation(&gp, a, b, c, ca->g, cb->g, cc->g);
FindPlaneEquation(&bp, a, b, c, ca->b, cb->b, cc->b);
FindPlaneEquation(&ap, a, b, c, ca->a, cb->a, cc->a);
}
}
}
if (needEye)
{
FindPlaneEquation(&exp, a, b, c, ea.x, eb.x, ec.x);
FindPlaneEquation(&eyp, a, b, c, ea.y, eb.y, ec.y);
// FindPlaneEquation(&ezp, a, b, c, ea.z, eb.z, ec.z);
FindPlaneEquation(&ewp, a, b, c, ea.w, eb.w, ec.w);
}
FindPlaneEquation(&nxp, a, b, c, na->x, nb->x, nc->x);
FindPlaneEquation(&nyp, a, b, c, na->y, nb->y, nc->y);
FindPlaneEquation(&nzp, a, b, c, na->z, nb->z, nc->z);
/*
** Compute general form of the line equations for each of the
** edges of the triangle.
*/
FindLineEqation(&tm.ab, a, b, c);
FindLineEqation(&tm.bc, b, c, a);
FindLineEqation(&tm.ca, c, a, b);
/* Compute bounding box of the triangle */
left = (GLint)a->window.x;
if (b->window.x < left) left = (GLint)b->window.x;
if (c->window.x < left) left = (GLint)c->window.x;
right = (GLint)a->window.x;
if (b->window.x > right) right = (GLint)b->window.x;
if (c->window.x > right) right = (GLint)c->window.x;
bottom = (GLint)a->window.y;
if (b->window.y < bottom) bottom = (GLint)b->window.y;
if (c->window.y < bottom) bottom = (GLint)c->window.y;
top = (GLint)a->window.y;
if (b->window.y > top) top = (GLint)b->window.y;
if (c->window.y > top) top = (GLint)c->window.y;
/* Bloat the bounding box when anti aliasing */
left -= (GLint)FILTER_WIDTH;
right += (GLint)FILTER_WIDTH;
bottom -= (GLint)FILTER_HEIGHT;
top += (GLint)FILTER_HEIGHT;
/* Init coverage computations */
samples = (gc->state.hints.polygonSmooth == GL_NICEST) ? 8 : 4;
ComputeCoverageStuff(&cs, samples);
/* Scan over the bounding box of the triangle */
for (y = bottom; y <= top; y++)
{
cs.lastCoverageWasOne = GL_FALSE;
for (x = left; x <= right; x++)
{
__GLfloat coverage;
__GLfloat xs, ys;
if (modeFlags & __GL_SHADE_STIPPLE)
{
/*
** Check the window coordinate against the stipple and
** and see if the pixel can be written
*/
GLint row = y & 31;
GLint col = x & 31;
if ((gc->polygon.stipple[row] & (1<<col)) == 0)
{
/*
** Stipple bit is clear. Do not render this pixel
** of the triangle.
*/
continue;
}
}
xs = x + __glHalf; /* sample point is at pixel center */
ys = y + __glHalf;
coverage = Coverage(&tm, &xs, &ys, &cs);
if (coverage != zero)
{
__GLfragment frag;
/*
** Fill in fragment for rendering. First compute the color
** of the fragment.
*/
phong->nTmp.x = FindP(&nxp, xs, ys);
phong->nTmp.y = FindP(&nyp, xs, ys);
phong->nTmp.z = FindP(&nzp, xs, ys);
if (needColor)
{
phong->tmpColor.r = FindP(&rp, xs, ys);
if (modeFlags & __GL_SHADE_RGB)
{
phong->tmpColor.g = FindP(&gp, xs, ys);
phong->tmpColor.b = FindP(&bp, xs, ys);
phong->tmpColor.a = FindP(&ap, xs, ys);
}
}
if (needEye)
{
phong->eTmp.x = FindP(&exp, xs, ys);
phong->eTmp.y = FindP(&eyp, xs, ys);
phong->eTmp.z = FindP(&ezp, xs, ys);
phong->eTmp.w = FindP(&ewp, xs, ys);
}
if (modeFlags & __GL_SHADE_RGB)
(*gc->procs.phong.ComputeRGBColor) (gc, &(frag.color));
else
(*gc->procs.phong.ComputeCIColor) (gc, &(frag.color));
/*
** Texture the fragment.
*/
if (modeFlags & __GL_SHADE_TEXTURE) {
__GLfloat qw, s, t, rho;
qw = FindP(&qwp, xs, ys);
s = FindP(&sp, xs, ys);
t = FindP(&tp, xs, ys);
rho = (*gc->procs.calcPolygonRho)(gc, sh, s, t, qw);
if( qw == (__GLfloat) 0.0 )
s = t = (__GLfloat) 0;
else {
s /= qw;
t /= qw;
}
(*gc->procs.texture)(gc, &frag.color, s, t, rho);
}
/*
** Fog the resulting color.
*/
if (modeFlags & __GL_SHADE_COMPUTE_FOG)
{
__GLfloat eyeZ = FindP(&ezp, xs, ys);
__glFogFragmentSlow(gc, &frag, eyeZ);
}
else if (modeFlags & __GL_SHADE_INTERP_FOG)
{
__GLfloat fog = FindP(&fp, xs, ys);
__glFogColorSlow(gc, &(frag.color), &(frag.color), fog);
}
/*
** Apply anti-aliasing effect
*/
if (rgbMode) {
frag.color.a *= coverage;
} else {
frag.color.r =
__glBuildAntiAliasIndex(frag.color.r,
coverage);
}
/*
** Finally, render the fragment.
*/
frag.x = (GLint)xs;
frag.y = (GLint)ys;
if (modeFlags & __GL_SHADE_DEPTH_ITER) {
frag.z = (__GLzValue)FindP(&zp, xs, ys);
}
(*gc->procs.store)(cfb, &frag);
}
}
}
#endif
}
#endif //GL_WIN_phong_shading