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/* $Id: linetemp.h,v 1.3 1997/06/20 02:49:53 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 2.3
* Copyright (C) 1995-1997 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: linetemp.h,v $
* Revision 1.3 1997/06/20 02:49:53 brianp
* changed color components from GLfixed to GLubyte
*
* Revision 1.2 1997/05/16 01:54:54 brianp
* zPtrYstep calculation was negated!
*
* Revision 1.1 1997/03/16 02:07:56 brianp
* Initial revision
*
*/
/*
* Line Rasterizer Template
*
* This file is #include'd to generate custom line rasterizers.
*
* The following macros may be defined to indicate what auxillary information
* must be interplated along the line:
* 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 directly compute pixel addresses during
* rasterization (see pixelPtr):
* 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
* SETUP_CODE - code which is to be executed once per line
*
* To enable line stippling define STIPPLE = 1
* To enable wide lines define WIDE = 1
*
* To actually "plot" each pixel either the PLOT macro or
* (XMAJOR_PLOT and YMAJOR_PLOT macros) must be defined...
* PLOT(X,Y) - code to plot a pixel. Example:
* if (Z < *zPtr) {
* *zPtr = Z;
* color = pack_rgb( FixedToInt(r0), FixedToInt(g0),
* FixedToInt(b0) );
* put_pixel( X, Y, color );
* }
*
* This code was designed for the origin to be in the lower-left corner.
*
*/
/*void line( GLcontext *ctx, GLuint vert0, GLuint vert1, GLuint pvert )*/
{
struct vertex_buffer *VB = ctx->VB;
/*
GLint x0 = (GLint) VB->Win[vert0][0], dx = (GLint) VB->Win[vert1][0] - x0;
GLint y0 = (GLint) VB->Win[vert0][1], dy = (GLint) VB->Win[vert1][1] - y0;
*/
GLint x0 = (GLint) VB->Win[vert0][0], x1 = (GLint) VB->Win[vert1][0];
GLint y0 = (GLint) VB->Win[vert0][1], y1 = (GLint) VB->Win[vert1][1];
GLint dx, dy;
#if INTERP_XY
GLint xstep, ystep;
#endif
#if INTERP_Z
GLint z0, z1, dz, zPtrXstep, zPtrYstep;
GLdepth *zPtr;
#endif
#if INTERP_RGB
GLfixed r0 = IntToFixed(VB->Color[vert0][0]);
GLfixed dr = IntToFixed(VB->Color[vert1][0]) - r0;
GLfixed g0 = IntToFixed(VB->Color[vert0][1]);
GLfixed dg = IntToFixed(VB->Color[vert1][1]) - g0;
GLfixed b0 = IntToFixed(VB->Color[vert0][2]);
GLfixed db = IntToFixed(VB->Color[vert1][2]) - b0;
#endif
#if INTERP_ALPHA
GLfixed a0 = IntToFixed(VB->Color[vert0][3]);
GLfixed da = IntToFixed(VB->Color[vert1][3]) - a0;
#endif
#if INTERP_INDEX
GLint i0 = VB->Index[vert0] << 8, di = (GLint) (VB->Index[vert1] << 8)-i0;
#endif
#if INTERP_ST
GLfixed s0 = FloatToFixed(VB->TexCoord[vert0][0] * S_SCALE);
GLfixed ds = FloatToFixed(VB->TexCoord[vert1][0] * S_SCALE) - s0;
GLfixed t0 = FloatToFixed(VB->TexCoord[vert0][1] * T_SCALE);
GLfixed dt = FloatToFixed(VB->TexCoord[vert1][1] * T_SCALE) - t0;
#endif
#if INTERP_STW
GLfloat s0 = VB->TexCoord[vert0][0], ds = VB->TexCoord[vert1][0] - s0;
GLfloat t0 = VB->TexCoord[vert0][1], dt = VB->TexCoord[vert1][1] - t0;
GLfloat w0 = 1.0F / VB->Clip[vert0][3], dw = 1.0F / VB->Clip[vert1][3] - w0;
#endif
#if INTERP_UV
GLfloat u0 = VB->TexCoord[vert0][2], du = VB->TexCoord[vert1][2] - u0;
GLfloat v0 = VB->TexCoord[vert0][3], dv = VB->TexCoord[vert1][3] - v0;
#endif
#ifdef PIXEL_ADDRESS
PIXEL_TYPE *pixelPtr;
GLint pixelXstep, pixelYstep;
#endif
#if WIDE
GLint width, min, max;
width = (GLint) CLAMP( ctx->Line.Width, MIN_LINE_WIDTH, MAX_LINE_WIDTH );
min = -width / 2;
max = min + width - 1;
#endif
/*
* Despite being clipped to the view volume, the line's window coordinates
* may just lie outside the window bounds. That is, if the legal window
* coordinates are [0,W-1][0,H-1], it's possible for x==W and/or y==H.
* This quick and dirty code nudges the endpoints inside the window if
* necessary.
*/
#if CLIP_HACK
{
GLint w = ctx->Buffer->Width;
GLint h = ctx->Buffer->Height;
if ((x0==w) | (x1==w)) {
if ((x0==w) & (x1==w))
return;
x0 -= x0==w;
x1 -= x1==w;
}
if ((y0==h) | (y1==h)) {
if ((y0==h) & (y1==h))
return;
y0 -= y0==h;
y1 -= y1==h;
}
}
#endif
dx = x1 - x0;
dy = y1 - y0;
if (dx==0 && dy==0) {
return;
}
/*
* Setup
*/
#ifdef SETUP_CODE
SETUP_CODE
#endif
#if INTERP_Z
zPtr = Z_ADDRESS(ctx,x0,y0);
# if DEPTH_BITS==16
z0 = FloatToFixed(VB->Win[vert0][2]);
z1 = FloatToFixed(VB->Win[vert1][2]);
# else
z0 = (int) VB->Win[vert0][2];
z1 = (int) VB->Win[vert1][2];
# endif
#endif
#ifdef PIXEL_ADDRESS
pixelPtr = (PIXEL_TYPE *) PIXEL_ADDRESS(x0,y0);
#endif
if (dx<0) {
dx = -dx; /* make positive */
#if INTERP_XY
xstep = -1;
#endif
#ifdef INTERP_Z
zPtrXstep = -sizeof(GLdepth);
#endif
#ifdef PIXEL_ADDRESS
pixelXstep = -sizeof(PIXEL_TYPE);
#endif
}
else {
#if INTERP_XY
xstep = 1;
#endif
#if INTERP_Z
zPtrXstep = sizeof(GLdepth);
#endif
#ifdef PIXEL_ADDRESS
pixelXstep = sizeof(PIXEL_TYPE);
#endif
}
if (dy<0) {
dy = -dy; /* make positive */
#if INTERP_XY
ystep = -1;
#endif
#if INTERP_Z
zPtrYstep = -ctx->Buffer->Width * sizeof(GLdepth);
#endif
#ifdef PIXEL_ADDRESS
pixelYstep = BYTES_PER_ROW;
#endif
}
else {
#if INTERP_XY
ystep = 1;
#endif
#if INTERP_Z
zPtrYstep = ctx->Buffer->Width * sizeof(GLdepth);
#endif
#ifdef PIXEL_ADDRESS
pixelYstep = -(BYTES_PER_ROW);
#endif
}
/*
* Draw
*/
if (dx>dy) {
/*
* X-major line
*/
GLint i;
GLint errorInc = dy+dy;
GLint error = errorInc-dx;
GLint errorDec = error-dx;
#if INTERP_Z
dz = (z1-z0) / dx;
#endif
#if INTERP_RGB
dr /= dx; /* convert from whole line delta to per-pixel delta */
dg /= dx;
db /= dx;
#endif
#if INTERP_ALPHA
da /= dx;
#endif
#if INTERP_INDEX
di /= dx;
#endif
#if INTERP_ST
ds /= dx;
dt /= dx;
#endif
#if INTERP_STW
{
GLfloat fdxinv = 1.0F / (GLfloat) dx;
ds *= fdxinv;
dt *= fdxinv;
dw *= fdxinv;
#if INTERP_UV
du *= fdxinv;
dv *= fdxinv;
#endif
}
#endif
for (i=0;i<dx;i++) {
#if STIPPLE
GLushort m;
m = 1 << ((ctx->StippleCounter/ctx->Line.StippleFactor) & 0xf);
if (ctx->Line.StipplePattern & m) {
#endif
#if INTERP_Z
# if DEPTH_BITS==16
GLdepth Z = FixedToInt(z0);
# else
GLdepth Z = z0;
# endif
#endif
#if INTERP_INDEX
GLint I = i0 >> 8;
#endif
#if WIDE
GLint yy;
GLint ymin = y0 + min;
GLint ymax = y0 + max;
for (yy=ymin;yy<=ymax;yy++) {
PLOT( x0, yy );
}
#else
# ifdef XMAJOR_PLOT
XMAJOR_PLOT( x0, y0 );
# else
PLOT( x0, y0 );
# endif
#endif /*WIDE*/
#if STIPPLE
}
ctx->StippleCounter++;
#endif
#if INTERP_XY
x0 += xstep;
#endif
#if INTERP_Z
zPtr = (GLdepth *) ((GLubyte*) zPtr + zPtrXstep);
z0 += dz;
#endif
#if INTERP_RGB
r0 += dr;
g0 += dg;
b0 += db;
#endif
#if INTERP_ALPHA
a0 += da;
#endif
#if INTERP_INDEX
i0 += di;
#endif
#if INTERP_ST
s0 += ds;
t0 += dt;
#endif
#if INTERP_STW
s0 += ds;
t0 += dt;
w0 += dw;
#endif
#if INTERP_UV
u0 += du;
v0 += dv;
#endif
#ifdef PIXEL_ADDRESS
pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelXstep);
#endif
if (error<0) {
error += errorInc;
}
else {
error += errorDec;
#if INTERP_XY
y0 += ystep;
#endif
#if INTERP_Z
zPtr = (GLdepth *) ((GLubyte*) zPtr + zPtrYstep);
#endif
#ifdef PIXEL_ADDRESS
pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelYstep);
#endif
}
}
}
else {
/*
* Y-major line
*/
GLint i;
GLint errorInc = dx+dx;
GLint error = errorInc-dy;
GLint errorDec = error-dy;
#if INTERP_Z
dz = (z1-z0) / dy;
#endif
#if INTERP_RGB
dr /= dy; /* convert from whole line delta to per-pixel delta */
dg /= dy;
db /= dy;
#endif
#if INTERP_ALPHA
da /= dy;
#endif
#if INTERP_INDEX
di /= dy;
#endif
#if INTERP_ST
ds /= dy;
dt /= dy;
#endif
#if INTERP_STW
{
GLfloat fdyinv = 1.0F / (GLfloat) dy;
ds *= fdyinv;
dt *= fdyinv;
dw *= fdyinv;
#if INTERP_UV
du *= fdyinv;
dv *= fdyinv;
#endif
}
#endif
for (i=0;i<dy;i++) {
#if STIPPLE
GLushort m;
m = 1 << ((ctx->StippleCounter/ctx->Line.StippleFactor) & 0xf);
if (ctx->Line.StipplePattern & m) {
#endif
#if INTERP_Z
# if DEPTH_BITS==16
GLdepth Z = FixedToInt(z0);
# else
GLdepth Z = z0;
# endif
#endif
#if INTERP_INDEX
GLint I = i0 >> 8;
#endif
#if WIDE
GLint xx;
GLint xmin = x0 + min;
GLint xmax = x0 + max;
for (xx=xmin;xx<=xmax;xx++) {
PLOT( xx, y0 );
}
#else
# ifdef YMAJOR_PLOT
YMAJOR_PLOT( x0, y0 );
# else
PLOT( x0, y0 );
# endif
#endif /*WIDE*/
#if STIPPLE
}
ctx->StippleCounter++;
#endif
#if INTERP_XY
y0 += ystep;
#endif
#if INTERP_Z
zPtr = (GLdepth *) ((GLubyte*) zPtr + zPtrYstep);
z0 += dz;
#endif
#if INTERP_RGB
r0 += dr;
g0 += dg;
b0 += db;
#endif
#if INTERP_ALPHA
a0 += da;
#endif
#if INTERP_INDEX
i0 += di;
#endif
#if INTERP_ST
s0 += ds;
t0 += dt;
#endif
#if INTERP_STW
s0 += ds;
t0 += dt;
w0 += dw;
#endif
#if INTERP_UV
u0 += du;
v0 += dv;
#endif
#ifdef PIXEL_ADDRESS
pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelYstep);
#endif
if (error<0) {
error += errorInc;
}
else {
error += errorDec;
#if INTERP_XY
x0 += xstep;
#endif
#if INTERP_Z
zPtr = (GLdepth *) ((GLubyte*) zPtr + zPtrXstep);
#endif
#ifdef PIXEL_ADDRESS
pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelXstep);
#endif
}
}
}
}
#undef INTERP_XY
#undef INTERP_Z
#undef INTERP_RGB
#undef INTERP_ALPHA
#undef INTERP_INDEX
#undef PIXEL_ADDRESS
#undef PIXEL_TYPE
#undef BYTES_PER_ROW
#undef SETUP_CODE
#undef PLOT
#undef XMAJOR_PLOT
#undef YMAJOR_PLOT
#undef CLIP_HACK
#undef STIPPLE
#undef WIDE
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.