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general_clip.h
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2000-01-07
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/* $Id: general_clip.h,v 1.2 1999/11/09 17:00:25 keithw Exp $ */
/*
* Mesa 3-D graphics library
* Version: 3.1
*
* Copyright (C) 1999 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.
*/
/*
* New (3.1) transformation code written by Keith Whitwell.
*/
/*
* Clip against +X
*
* The if conditions are known at compile time.
*/
#define PLANE (CLIP_RIGHT_BIT)
#define INSIDE(K) (X(K) <= W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dx = X(out)-X(in); \
dw = W(out)-W(in); \
t = (X(in)-W(in)) / (dw-dx); \
neww = W(in) + t * dw; \
X(new) = neww; \
Y(new) = Y(in) + t * (Y(out) - Y(in)); \
if (SIZE>=3) coord[new][2] = Z(in) + t * (Z(out) - Z(in)); \
if (SIZE==4) coord[new][3] = neww;
GENERAL_CLIP
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
/*
* Clip against -X
*/
#define PLANE (CLIP_LEFT_BIT)
#define INSIDE(K) (X(K) >= -W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dx = X(out)-X(in); \
dw = W(out)-W(in); \
t = -(X(in)+W(in)) / (dw+dx); \
neww = W(in) + t * dw; \
X(new) = -neww; \
Y(new) = Y(in) + t * (Y(out) - Y(in)); \
if (SIZE>=3) coord[new][2] = Z(in) + t * (Z(out) - Z(in)); \
if (SIZE==4) coord[new][3] = neww;
GENERAL_CLIP
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
/*
* Clip against +Y
*/
#define PLANE (CLIP_TOP_BIT)
#define INSIDE(K) (Y(K) <= W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dy = Y(out)-Y(in); \
dw = W(out)-W(in); \
t = (Y(in)-W(in)) / (dw-dy); \
neww = W(in) + t * dw; \
X(new) = X(in) + t * (X(out) - X(in)); \
Y(new) = neww; \
if (SIZE>=3) coord[new][2] = Z(in) + t * (Z(out) - Z(in)); \
if (SIZE==4) coord[new][3] = neww;
GENERAL_CLIP
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
/*
* Clip against -Y
*/
#define PLANE (CLIP_BOTTOM_BIT)
#define INSIDE(K) (Y(K) >= -W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dy = Y(out)-Y(in); \
dw = W(out)-W(in); \
t = -(Y(in)+W(in)) / (dw+dy); \
neww = W(in) + t * dw; \
X(new) = X(in) + t * (X(out) - X(in)); \
Y(new) = -neww; \
if (SIZE>=3) coord[new][2] = Z(in) + t * (Z(out) - Z(in)); \
if (SIZE==4) coord[new][3] = neww;
GENERAL_CLIP
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
/*
* Clip against +Z
*/
#define PLANE (CLIP_FAR_BIT)
#define INSIDE(K) (Z(K) <= W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dz = Z(out)-Z(in); \
dw = W(out)-W(in); \
t = (Z(in)-W(in)) / (dw-dz); \
neww = W(in) + t * dw; \
X(new) = X(in) + t * (X(out) - X(in)); \
Y(new) = Y(in) + t * (Y(out) - Y(in)); \
coord[new][2] = neww; \
if (SIZE==4) coord[new][3] = neww;
if (SIZE>=3) {
GENERAL_CLIP
}
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
/*
* Clip against -Z
*/
#define PLANE (CLIP_NEAR_BIT)
#define INSIDE(K) (Z(K) >= -W(K))
#define COMPUTE_INTERSECTION( in, out, new ) \
dz = Z(out)-Z(in); \
dw = W(out)-W(in); \
t = -(Z(in)+W(in)) / (dw+dz); \
neww = W(in) + t * dw; \
X(new) = X(in) + t * (X(out) - X(in)); \
Y(new) = Y(in) + t * (Y(out) - Y(in)); \
coord[new][2] = -neww; \
if (SIZE==4) coord[new][3] = neww;
if (SIZE>=3) {
GENERAL_CLIP
}
#undef INSIDE
#undef PLANE
#undef COMPUTE_INTERSECTION
#undef GENERAL_CLIP