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/* $Id: s_scissor.c,v 1.1.1.1 2002/10/22 13:06:51 alanh Exp $ */
/*
* Mesa 3-D graphics library
* Version: 3.5
*
* Copyright (C) 1999-2001 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.
*/
#include "glheader.h"
#include "macros.h"
#include "mem.h"
#include "s_context.h"
#include "s_scissor.h"
/*
* Apply the scissor test to a span of pixels.
* Return: 0 = all pixels in the span are outside the scissor box.
* n = mask[n-1] is the last one to be visible
*/
GLuint
_mesa_scissor_span(GLcontext *ctx, GLuint n, GLint x, GLint y, GLubyte mask[])
{
/* first check if whole span is outside the scissor box */
if (y < ctx->DrawBuffer->_Ymin
|| y >= ctx->DrawBuffer->_Ymax
|| x > ctx->DrawBuffer->_Xmax
|| x + (GLint) n - 1 < ctx->DrawBuffer->_Xmin) {
return 0;
}
else {
const GLint xMin = ctx->DrawBuffer->_Xmin;
const GLint xMax = ctx->DrawBuffer->_Xmax;
if (x < xMin)
BZERO(mask, (xMin-x) * sizeof(GLubyte));
if (x + (GLint) n > xMax) {
BZERO(mask + xMax - x, (n - (xMax - x)) * sizeof(GLubyte));
return (GLuint) (xMax - x);
}
return n;
}
}
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