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/* $Id: tritemp.h,v 1.6 1996/10/01 04:13:09 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 2.0
* Copyright (C) 1995-1996 Brian Paul
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* $Log: tritemp.h,v $
* Revision 1.6 1996/10/01 04:13:09 brianp
* fixed Z interpolation for >16-bit depth buffer
* added color underflow error check
*
* Revision 1.5 1996/09/27 01:32:59 brianp
* removed unused variables
*
* Revision 1.4 1996/09/18 01:03:43 brianp
* tightened threshold for culling by area
*
* Revision 1.3 1996/09/15 14:19:16 brianp
* now use GLframebuffer and GLvisual
*
* Revision 1.2 1996/09/14 06:41:38 brianp
* perspective correct texture code wasn't sub-pixel accurate (Doug Rabson)
*
* Revision 1.1 1996/09/13 01:38:16 brianp
* Initial revision
*
*/
/*
* Triangle Rasterizer Template
*
* This file is #include'd to generate custom triangle rasterizers.
*
* The following macros may be defined to indicate what auxillary information
* must be interplated across the triangle:
* INTERP_Z - if defined, interpolate Z values
* INTERP_RGB - if defined, interpolate RGB values
* INTERP_ALPHA - if defined, interpolate Alpha values
* INTERP_INDEX - if defined, interpolate color index values
* INTERP_ST - if defined, interpolate integer ST texcoords
* (fast, simple 2-D texture mapping)
* INTERP_STW - if defined, interpolate float ST texcoords and W
* (2-D texture maps with perspective correction)
* INTERP_UV - if defined, interpolate float UV texcoords too
* (for 3-D, 4-D? texture maps)
*
* When one can directly address pixels in the color buffer the following
* macros can be defined and used to compute pixel addresses during
* rasterization (see pRow):
* PIXEL_TYPE - the datatype of a pixel (GLubyte, GLushort, GLuint)
* BYTES_PER_ROW - number of bytes per row in the color buffer
* PIXEL_ADDRESS(X,Y) - returns the address of pixel at (X,Y) where
* Y==0 at bottom of screen and increases upward.
*
* Optionally, one may provide one-time setup code per triangle:
* SETUP_CODE - code which is to be executed once per triangle
*
* The following macro MUST be defined:
* INNER_LOOP(LEFT,RIGHT,Y) - code to write a span of pixels.
* Something like:
*
* for (x=LEFT; x<RIGHT;x++) {
* put_pixel(x,Y);
* // increment fixed point interpolants
* }
*
* This code was designed for the origin to be in the lower-left corner.
*
* Inspired by triangle rasterizer code written by Allen Akin. Thanks Allen!
*/
/*void triangle( GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv )*/
{
typedef struct {
GLint v0, v1; /* Y(v0) < Y(v1) */
GLfloat dx; /* X(v1) - X(v0) */
GLfloat dy; /* Y(v1) - Y(v0) */
GLfixed fdxdy; /* dx/dy in fixed-point */
GLfixed fsx; /* first sample point x coord */
GLfixed fsy;
GLfloat adjy; /* adjust from v[0]->fy to fsy, scaled */
GLint lines; /* number of lines to be sampled on this edge */
GLfixed fx0; /* fixed pt X of lower endpoint */
} EdgeT;
struct vertex_buffer *VB = ctx->VB;
EdgeT eMaj, eTop, eBot;
GLfloat oneOverArea;
int vMin, vMid, vMax; /* vertex indexes: Y(vMin)<=Y(vMid)<=Y(vMax) */
/* find the order of the 3 vertices along the Y axis */
{
GLfloat y0 = VB->Win[v0][1];
GLfloat y1 = VB->Win[v1][1];
GLfloat y2 = VB->Win[v2][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; /* y0<=y2<=y1 */
}
}
else {
if (y0<=y2) {
vMin = v1; vMid = v0; vMax = v2; /* y1<=y0<=y2 */
}
else if (y2<=y1) {
vMin = v2; vMid = v1; vMax = v0; /* y2<=y1<=y0 */
}
else {
vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */
}
}
}
/* vertex/edge relationship */
eMaj.v0 = vMin; eMaj.v1 = vMax; /*TODO: .v1's not needed */
eTop.v0 = vMid; eTop.v1 = vMax;
eBot.v0 = vMin; eBot.v1 = vMid;
/* compute deltas for each edge: vertex[v1] - vertex[v0] */
eMaj.dx = VB->Win[vMax][0] - VB->Win[vMin][0];
eMaj.dy = VB->Win[vMax][1] - VB->Win[vMin][1];
eTop.dx = VB->Win[vMax][0] - VB->Win[vMid][0];
eTop.dy = VB->Win[vMax][1] - VB->Win[vMid][1];
eBot.dx = VB->Win[vMid][0] - VB->Win[vMin][0];
eBot.dy = VB->Win[vMid][1] - VB->Win[vMin][1];
/* compute oneOverArea */
{
GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
if (area>-0.05f && area<0.05f) {
return; /* very small; CULLED */
}
oneOverArea = 1.0F / area;
}
/* Edge setup. For a triangle strip these could be reused... */
{
/* fixed point Y coordinates */
GLfixed vMin_fx = FloatToFixed(VB->Win[vMin][0] + 0.5F);
GLfixed vMin_fy = FloatToFixed(VB->Win[vMin][1] - 0.5F);
GLfixed vMid_fx = FloatToFixed(VB->Win[vMid][0] + 0.5F);
GLfixed vMid_fy = FloatToFixed(VB->Win[vMid][1] - 0.5F);
GLfixed vMax_fy = FloatToFixed(VB->Win[vMax][1] - 0.5F);
eMaj.fsy = FixedCeil(vMin_fy);
eMaj.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eMaj.fsy);
if (eMaj.lines > 0) {
GLfloat dxdy = eMaj.dx / eMaj.dy;
eMaj.fdxdy = SignedFloatToFixed(dxdy);
eMaj.adjy = (GLfloat) (eMaj.fsy - vMin_fy); /* SCALED! */
eMaj.fx0 = vMin_fx;
eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * dxdy);
}
else {
return; /*CULLED*/
}
eTop.fsy = FixedCeil(vMid_fy);
eTop.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eTop.fsy);
if (eTop.lines > 0) {
GLfloat dxdy = eTop.dx / eTop.dy;
eTop.fdxdy = SignedFloatToFixed(dxdy);
eTop.adjy = (GLfloat) (eTop.fsy - vMid_fy); /* SCALED! */
eTop.fx0 = vMid_fx;
eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * dxdy);
}
eBot.fsy = FixedCeil(vMin_fy);
eBot.lines = FixedToInt(vMid_fy + FIXED_ONE - FIXED_EPSILON - eBot.fsy);
if (eBot.lines > 0) {
GLfloat dxdy = eBot.dx / eBot.dy;
eBot.fdxdy = SignedFloatToFixed(dxdy);
eBot.adjy = (GLfloat) (eBot.fsy - vMin_fy); /* SCALED! */
eBot.fx0 = vMin_fx;
eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * dxdy);
}
}
/*
* Conceptually, we view a triangle as two subtriangles
* separated by a perfectly horizontal line. The edge that is
* intersected by this line is one with maximal absolute dy; we
* call it a ``major'' edge. The other two edges are the
* ``top'' edge (for the upper subtriangle) and the ``bottom''
* edge (for the lower subtriangle). If either of these two
* edges is horizontal or very close to horizontal, the
* corresponding subtriangle might cover zero sample points;
* we take care to handle such cases, for performance as well
* as correctness.
*
* By stepping rasterization parameters along the major edge,
* we can avoid recomputing them at the discontinuity where
* the top and bottom edges meet. However, this forces us to
* be able to scan both left-to-right and right-to-left.
* Also, we must determine whether the major edge is at the
* left or right side of the triangle. We do this by
* computing the magnitude of the cross-product of the major
* and top edges. Since this magnitude depends on the sine of
* the angle between the two edges, its sign tells us whether
* we turn to the left or to the right when travelling along
* the major edge to the top edge, and from this we infer
* whether the major edge is on the left or the right.
*
* Serendipitously, this cross-product magnitude is also a
* value we need to compute the iteration parameter
* derivatives for the triangle, and it can be used to perform
* backface culling because its sign tells us whether the
* triangle is clockwise or counterclockwise. In this code we
* refer to it as ``area'' because it's also proportional to
* the pixel area of the triangle.
*/
{
GLint ltor; /* true if scanning left-to-right */
#if INTERP_Z
GLfloat dzdx, dzdy; GLfixed fdzdx;
#endif
#if INTERP_RGB
GLfloat drdx, drdy; GLfixed fdrdx;
GLfloat dgdx, dgdy; GLfixed fdgdx;
GLfloat dbdx, dbdy; GLfixed fdbdx;
#endif
#if INTERP_ALPHA
GLfloat dadx, dady; GLfixed fdadx;
#endif
#if INTERP_INDEX
GLfloat didx, didy; GLfixed fdidx;
#endif
#if INTERP_ST
GLfloat dsdx, dsdy; GLfixed fdsdx;
GLfloat dtdx, dtdy; GLfixed fdtdx;
#endif
#if INTERP_STW
GLfloat dsdx, dsdy;
GLfloat dtdx, dtdy;
GLfloat dwdx, dwdy;
#endif
#if INTERP_UV
GLfloat dudx, dudy;
GLfloat dvdx, dvdy;
#endif
/*
* Execute user-supplied setup code
*/
#ifdef SETUP_CODE
SETUP_CODE
#endif
ltor = (oneOverArea < 0.0F);
/* compute d?/dx and d?/dy derivatives */
#if INTERP_Z
{
GLfloat eMaj_dz, eBot_dz;
eMaj_dz = VB->Win[vMax][2] - VB->Win[vMin][2];
eBot_dz = VB->Win[vMid][2] - VB->Win[vMin][2];
dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
#if DEPTH_BITS==16
fdzdx = SignedFloatToFixed(dzdx);
#else
fdzdx = (GLint) dzdx;
#endif
dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
}
#endif
#if INTERP_RGB
{
GLfloat eMaj_dr, eBot_dr;
eMaj_dr = FixedToFloat( VB->Color[vMax][0] - VB->Color[vMin][0] );
eBot_dr = FixedToFloat( VB->Color[vMid][0] - VB->Color[vMin][0] );
drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
fdrdx = SignedFloatToFixed(drdx);
drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
}
{
GLfloat eMaj_dg, eBot_dg;
eMaj_dg = FixedToFloat( VB->Color[vMax][1] - VB->Color[vMin][1] );
eBot_dg = FixedToFloat( VB->Color[vMid][1] - VB->Color[vMin][1] );
dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
fdgdx = SignedFloatToFixed(dgdx);
dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
}
{
GLfloat eMaj_db, eBot_db;
eMaj_db = FixedToFloat( VB->Color[vMax][2] - VB->Color[vMin][2] );
eBot_db = FixedToFloat( VB->Color[vMid][2] - VB->Color[vMin][2] );
dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
fdbdx = SignedFloatToFixed(dbdx);
dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
}
#endif
#if INTERP_ALPHA
{
GLfloat eMaj_da, eBot_da;
eMaj_da = FixedToFloat( VB->Color[vMax][3] - VB->Color[vMin][3] );
eBot_da = FixedToFloat( VB->Color[vMid][3] - VB->Color[vMin][3] );
dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
fdadx = SignedFloatToFixed(dadx);
dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
}
#endif
#if INTERP_INDEX
{
GLfloat eMaj_di, eBot_di;
eMaj_di = (GLint) VB->Index[vMax] - (GLint) VB->Index[vMin];
eBot_di = (GLint) VB->Index[vMid] - (GLint) VB->Index[vMin];
didx = oneOverArea * (eMaj_di * eBot.dy - eMaj.dy * eBot_di);
fdidx = SignedFloatToFixed(didx);
didy = oneOverArea * (eMaj.dx * eBot_di - eMaj_di * eBot.dx);
}
#endif
#if INTERP_ST
{
GLfloat eMaj_ds, eBot_ds;
eMaj_ds = (VB->TexCoord[vMax][0] - VB->TexCoord[vMin][0]) * S_SCALE;
eBot_ds = (VB->TexCoord[vMid][0] - VB->TexCoord[vMin][0]) * T_SCALE;
dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
fdsdx = SignedFloatToFixed(dsdx);
dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
}
{
GLfloat eMaj_dt, eBot_dt;
eMaj_dt = (VB->TexCoord[vMax][1] - VB->TexCoord[vMin][1]) * S_SCALE;
eBot_dt = (VB->TexCoord[vMid][1] - VB->TexCoord[vMin][1]) * T_SCALE;
dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
fdtdx = SignedFloatToFixed(dtdx);
dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
}
#endif
#if INTERP_STW
{
GLfloat wMax = 1.0F / VB->Clip[vMax][3];
GLfloat wMin = 1.0F / VB->Clip[vMin][3];
GLfloat wMid = 1.0F / VB->Clip[vMid][3];
GLfloat eMaj_dw, eBot_dw;
GLfloat eMaj_ds, eBot_ds;
GLfloat eMaj_dt, eBot_dt;
#if INTERP_UV
GLfloat eMaj_du, eBot_du;
GLfloat eMaj_dv, eBot_dv;
#endif
eMaj_dw = wMax - wMin;
eBot_dw = wMid - wMin;
dwdx = oneOverArea * (eMaj_dw * eBot.dy - eMaj.dy * eBot_dw);
dwdy = oneOverArea * (eMaj.dx * eBot_dw - eMaj_dw * eBot.dx);
eMaj_ds = VB->TexCoord[vMax][0]*wMax - VB->TexCoord[vMin][0]*wMin;
eBot_ds = VB->TexCoord[vMid][0]*wMid - VB->TexCoord[vMin][0]*wMin;
dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
eMaj_dt = VB->TexCoord[vMax][1]*wMax - VB->TexCoord[vMin][1]*wMin;
eBot_dt = VB->TexCoord[vMid][1]*wMid - VB->TexCoord[vMin][1]*wMin;
dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
#if INTERP_UV
eMaj_du = VB->TexCoord[vMax][2]*wMax - VB->TexCoord[vMin][1]*wMin;
eBot_du = VB->TexCoord[vMid][2]*wMid - VB->TexCoord[vMin][1]*wMin;
dudx = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du);
dudy = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx);
eMaj_dv = VB->TexCoord[vMax][3]*wMax - VB->TexCoord[vMin][3]*wMin;
eBot_dv = VB->TexCoord[vMid][3]*wMid - VB->TexCoord[vMin][3]*wMin;
dvdx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv);
dvdy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx);
#endif
}
#endif
/*
* We always sample at pixel centers. However, we avoid
* explicit half-pixel offsets in this code by incorporating
* the proper offset in each of x and y during the
* transformation to window coordinates.
*
* We also apply the usual rasterization rules to prevent
* cracks and overlaps. A pixel is considered inside a
* subtriangle if it meets all of four conditions: it is on or
* to the right of the left edge, strictly to the left of the
* right edge, on or below the top edge, and strictly above
* the bottom edge. (Some edges may be degenerate.)
*
* The following discussion assumes left-to-right scanning
* (that is, the major edge is on the left); the right-to-left
* case is a straightforward variation.
*
* We start by finding the half-integral y coordinate that is
* at or below the top of the triangle. This gives us the
* first scan line that could possibly contain pixels that are
* inside the triangle.
*
* Next we creep down the major edge until we reach that y,
* and compute the corresponding x coordinate on the edge.
* Then we find the half-integral x that lies on or just
* inside the edge. This is the first pixel that might lie in
* the interior of the triangle. (We won't know for sure
* until we check the other edges.)
*
* As we rasterize the triangle, we'll step down the major
* edge. For each step in y, we'll move an integer number
* of steps in x. There are two possible x step sizes, which
* we'll call the ``inner'' step (guaranteed to land on the
* edge or inside it) and the ``outer'' step (guaranteed to
* land on the edge or outside it). The inner and outer steps
* differ by one. During rasterization we maintain an error
* term that indicates our distance from the true edge, and
* select either the inner step or the outer step, whichever
* gets us to the first pixel that falls inside the triangle.
*
* All parameters (z, red, etc.) as well as the buffer
* addresses for color and z have inner and outer step values,
* so that we can increment them appropriately. This method
* eliminates the need to adjust parameters by creeping a
* sub-pixel amount into the triangle at each scanline.
*/
{
int subTriangle;
GLfixed fx, fxLeftEdge, fxRightEdge, fdxLeftEdge, fdxRightEdge;
GLfixed fdxOuter;
int idxOuter;
float dxOuter;
GLfixed fError, fdError;
float adjx, adjy;
GLfixed fy;
int iy;
#ifdef PIXEL_ADDRESS
PIXEL_TYPE *pRow;
int dPRowOuter, dPRowInner; /* offset in bytes */
#endif
#if INTERP_Z
GLdepth *zRow;
int dZRowOuter, dZRowInner; /* offset in bytes */
GLfixed fz, fdzOuter, fdzInner;
#endif
#if INTERP_RGB
GLfixed fr, fdrOuter, fdrInner;
GLfixed fg, fdgOuter, fdgInner;
GLfixed fb, fdbOuter, fdbInner;
#endif
#if INTERP_ALPHA
GLfixed fa, fdaOuter, fdaInner;
#endif
#if INTERP_INDEX
GLfixed fi, fdiOuter, fdiInner;
#endif
#if INTERP_ST
GLfixed fs, fdsOuter, fdsInner;
GLfixed ft, fdtOuter, fdtInner;
#endif
#if INTERP_STW
GLfloat sLeft, dsOuter, dsInner;
GLfloat tLeft, dtOuter, dtInner;
GLfloat wLeft, dwOuter, dwInner;
#endif
#if INTERP_UV
GLfloat uLeft, duOuter, duInner;
GLfloat vLeft, dvOuter, dvInner;
#endif
for (subTriangle=0; subTriangle<=1; subTriangle++) {
EdgeT *eLeft, *eRight;
int setupLeft, setupRight;
int lines;
if (subTriangle==0) {
/* bottom half */
if (ltor) {
eLeft = &eMaj;
eRight = &eBot;
lines = eRight->lines;
setupLeft = 1;
setupRight = 1;
}
else {
eLeft = &eBot;
eRight = &eMaj;
lines = eLeft->lines;
setupLeft = 1;
setupRight = 1;
}
}
else {
/* top half */
if (ltor) {
eLeft = &eMaj;
eRight = &eTop;
lines = eRight->lines;
setupLeft = 0;
setupRight = 1;
}
else {
eLeft = &eTop;
eRight = &eMaj;
lines = eLeft->lines;
setupLeft = 1;
setupRight = 0;
}
if (lines==0) return;
}
if (setupLeft && eLeft->lines>0) {
GLint vLower;
GLfixed fsx = eLeft->fsx;
fx = FixedCeil(fsx);
fError = fx - fsx - FIXED_ONE;
fxLeftEdge = fsx - FIXED_EPSILON;
fdxLeftEdge = eLeft->fdxdy;
fdxOuter = FixedFloor(fdxLeftEdge - FIXED_EPSILON);
fdError = fdxOuter - fdxLeftEdge + FIXED_ONE;
idxOuter = FixedToInt(fdxOuter);
dxOuter = (float) idxOuter;
fy = eLeft->fsy;
iy = FixedToInt(fy);
adjx = (float)(fx - eLeft->fx0); /* SCALED! */
adjy = eLeft->adjy; /* SCALED! */
vLower = eLeft->v0;
#ifdef PIXEL_ADDRESS
{
pRow = PIXEL_ADDRESS( FixedToInt(fxLeftEdge), iy );
dPRowOuter = -BYTES_PER_ROW + idxOuter * sizeof(PIXEL_TYPE);
/* negative because Y=0 at bottom and increases upward */
}
#endif
/*
* Now we need the set of parameter (z, color, etc.) values at
* the point (fx, fy). This gives us properly-sampled parameter
* values that we can step from pixel to pixel. Furthermore,
* although we might have intermediate results that overflow
* the normal parameter range when we step temporarily outside
* the triangle, we shouldn't overflow or underflow for any
* pixel that's actually inside the triangle.
*/
#if INTERP_Z
{
GLfloat z0;
z0 = VB->Win[vLower][2] + ctx->PolygonZoffset;
#if DEPTH_BITS==16
/* interpolate fixed-pt values */
fz = (GLfixed)(z0 * FIXED_SCALE + dzdx * adjx + dzdy * adjy) + FIXED_HALF;
fdzOuter = SignedFloatToFixed(dzdy + dxOuter * dzdx);
#else
/* interpolate depth values exactly */
fz = (GLint) (z0 + dzdx*FixedToFloat(adjx) + dzdy*FixedToFloat(adjy));
fdzOuter = (GLint) (dzdy + dxOuter * dzdx);
#endif
zRow = Z_ADDRESS( ctx, FixedToInt(fxLeftEdge), iy );
dZRowOuter = (ctx->Buffer->Width + idxOuter) * sizeof(GLdepth);
}
#endif
#if INTERP_RGB
fr = (GLfixed)(VB->Color[vLower][0] + drdx * adjx + drdy * adjy) + FIXED_HALF;
fdrOuter = SignedFloatToFixed(drdy + dxOuter * drdx);
fg = (GLfixed)(VB->Color[vLower][1] + dgdx * adjx + dgdy * adjy) + FIXED_HALF;
fdgOuter = SignedFloatToFixed(dgdy + dxOuter * dgdx);
fb = (GLfixed)(VB->Color[vLower][2] + dbdx * adjx + dbdy * adjy) + FIXED_HALF;
fdbOuter = SignedFloatToFixed(dbdy + dxOuter * dbdx);
#endif
#if INTERP_ALPHA
fa = (GLfixed)(VB->Color[vLower][3] + dadx * adjx + dady * adjy) + FIXED_HALF;
fdaOuter = SignedFloatToFixed(dady + dxOuter * dadx);
#endif
#if INTERP_INDEX
fi = (GLfixed)(VB->Index[vLower] * FIXED_SCALE + didx * adjx + didy * adjy) + FIXED_HALF;
fdiOuter = SignedFloatToFixed(didy + dxOuter * didx);
#endif
#if INTERP_ST
{
GLfloat s0, t0;
s0 = VB->TexCoord[vLower][0] * S_SCALE;
fs = (GLfixed)(s0 * FIXED_SCALE + dsdx * adjx + dsdy * adjy) + FIXED_HALF;
fdsOuter = SignedFloatToFixed(dsdy + dxOuter * dsdx);
t0 = VB->TexCoord[vLower][1] * T_SCALE;
ft = (GLfixed)(t0 * FIXED_SCALE + dtdx * adjx + dtdy * adjy) + FIXED_HALF;
fdtOuter = SignedFloatToFixed(dtdy + dxOuter * dtdx);
}
#endif
#if INTERP_STW
{
GLfloat w0 = 1.0F / VB->Clip[vLower][3];
GLfloat s0, t0, u0, v0;
wLeft = w0 + (dwdx * adjx + dwdy * adjy) * (1.0F/FIXED_SCALE);
dwOuter = dwdy + dxOuter * dwdx;
s0 = VB->TexCoord[vLower][0] * w0;
sLeft = s0 + (dsdx * adjx + dsdy * adjy) * (1.0F/FIXED_SCALE);
dsOuter = dsdy + dxOuter * dsdx;
t0 = VB->TexCoord[vLower][1] * w0;
tLeft = t0 + (dtdx * adjx + dtdy * adjy) * (1.0F/FIXED_SCALE);
dtOuter = dtdy + dxOuter * dtdx;
#if INTERP_UV
u0 = VB->TexCoord[vLower][2] * w0;
uLeft = u0 + (dudx * adjx + dudy * adjy) * (1.0F/FIXED_SCALE);
duOuter = dudy + dxOuter * dudx;
v0 = VB->TexCoord[vLower][3] * w0;
vLeft = v0 + (dvdx * adjx + dvdy * adjy) * (1.0F/FIXED_SCALE);
dvOuter = dvdy + dxOuter * dvdx;
#endif
}
#endif
} /*if setupLeft*/
if (setupRight) {
fxRightEdge = eRight->fsx - FIXED_EPSILON;
fdxRightEdge = eRight->fdxdy;
}
if (lines==0) {
continue;
}
/* Rasterize setup */
#ifdef PIXEL_ADDRESS
dPRowInner = dPRowOuter + sizeof(PIXEL_TYPE);
#endif
#if INTERP_Z
dZRowInner = dZRowOuter + sizeof(GLdepth);
fdzInner = fdzOuter + fdzdx;
#endif
#if INTERP_RGB
fdrInner = fdrOuter + fdrdx;
fdgInner = fdgOuter + fdgdx;
fdbInner = fdbOuter + fdbdx;
#endif
#if INTERP_ALPHA
fdaInner = fdaOuter + fdadx;
#endif
#if INTERP_INDEX
fdiInner = fdiOuter + fdidx;
#endif
#if INTERP_ST
fdsInner = fdsOuter + fdsdx;
fdtInner = fdtOuter + fdtdx;
#endif
#if INTERP_STW
dwInner = dwOuter + dwdx;
dsInner = dsOuter + dsdx;
dtInner = dtOuter + dtdx;
#if INTERP_UV
duInner = duOuter + dudx;
dvInner = dvOuter + dvdx;
#endif
#endif
while (lines>0) {
/* initialize the span interpolants to the leftmost value */
/* ff = fixed-pt fragment */
#if INTERP_Z
GLfixed ffz = fz;
GLdepth *zp = zRow;
#endif
#if INTERP_RGB
GLfixed ffr = fr, ffg = fg, ffb = fb;
#endif
#if INTERP_ALPHA
GLfixed ffa = fa;
#endif
#if INTERP_INDEX
GLfixed ffi = fi;
#endif
#if INTERP_ST
GLfixed ffs = fs, fft = ft;
#endif
#if INTERP_STW
GLfloat ss = sLeft, tt = tLeft, ww = wLeft;
#endif
#if INTERP_UV
GLfloat uu = uLeft, vv = vLeft;
#endif
GLint left = FixedToInt(fxLeftEdge);
GLint right = FixedToInt(fxRightEdge);
#if INTERP_RGB
if (right-left==1) {
/* need this to accomodate round-off errors */
if (ffr<0) ffr = 0;
if (ffg<0) ffg = 0;
if (ffb<0) ffb = 0;
}
#endif
INNER_LOOP( left, right, iy );
/*
* Advance to the next scan line. Compute the
* new edge coordinates, and adjust the
* pixel-center x coordinate so that it stays
* on or inside the major edge.
*/
iy++;
lines--;
fxLeftEdge += fdxLeftEdge;
fxRightEdge += fdxRightEdge;
fError += fdError;
if (fError >= 0) {
fError -= FIXED_ONE;
#ifdef PIXEL_ADDRESS
pRow = (PIXEL_TYPE*) ((GLubyte*)pRow + dPRowOuter);
#endif
#if INTERP_Z
zRow = (GLdepth*) ((GLubyte*)zRow + dZRowOuter);
fz += fdzOuter;
#endif
#if INTERP_RGB
fr += fdrOuter; fg += fdgOuter; fb += fdbOuter;
#endif
#if INTERP_ALPHA
fa += fdaOuter;
#endif
#if INTERP_INDEX
fi += fdiOuter;
#endif
#if INTERP_ST
fs += fdsOuter; ft += fdtOuter;
#endif
#if INTERP_STW
sLeft += dsOuter;
tLeft += dtOuter;
wLeft += dwOuter;
#endif
#if INTERP_UV
uLeft += duOuter;
vLeft += dvOuter;
#endif
}
else {
#ifdef PIXEL_ADDRESS
pRow = (PIXEL_TYPE*) ((GLubyte*)pRow + dPRowInner);
#endif
#if INTERP_Z
zRow = (GLdepth*) ((GLubyte*)zRow + dZRowInner);
fz += fdzInner;
#endif
#if INTERP_RGB
fr += fdrInner; fg += fdgInner; fb += fdbInner;
#endif
#if INTERP_ALPHA
fa += fdaInner;
#endif
#if INTERP_INDEX
fi += fdiInner;
#endif
#if INTERP_ST
fs += fdsInner; ft += fdtInner;
#endif
#if INTERP_STW
sLeft += dsInner;
tLeft += dtInner;
wLeft += dwInner;
#endif
#if INTERP_UV
uLeft += duInner;
vLeft += dvInner;
#endif
}
} /*while lines>0*/
} /* for subTriangle */
}
}
}
#undef SETUP_CODE
#undef INNER_LOOP
#undef PIXEL_TYPE
#undef BYTES_PER_ROW
#undef PIXEL_ADDRESS
#undef INTERP_Z
#undef INTERP_RGB
#undef INTERP_ALPHA
#undef INTERP_INDEX
#undef INTERP_ST
#undef INTERP_STW
#undef INTERP_UV
#undef S_SCALE
#undef T_SCALE
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.