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      1 /**************************************************************************
      2  *
      3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
     22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28  /*
     29   * Authors:
     30   *   Keith Whitwell <keith (at) tungstengraphics.com>
     31   */
     32 
     33 
     34 #include "main/macros.h"
     35 #include "st_context.h"
     36 #include "pipe/p_context.h"
     37 #include "st_atom.h"
     38 
     39 
     40 /**
     41  * Scissor depends on the scissor box, and the framebuffer dimensions.
     42  */
     43 static void
     44 update_scissor( struct st_context *st )
     45 {
     46    struct pipe_scissor_state scissor;
     47    const struct gl_context *ctx = st->ctx;
     48    const struct gl_framebuffer *fb = ctx->DrawBuffer;
     49    GLint miny, maxy;
     50 
     51    scissor.minx = 0;
     52    scissor.miny = 0;
     53    scissor.maxx = fb->Width;
     54    scissor.maxy = fb->Height;
     55 
     56    if (ctx->Scissor.Enabled) {
     57       /* need to be careful here with xmax or ymax < 0 */
     58       GLint xmax = MAX2(0, ctx->Scissor.X + ctx->Scissor.Width);
     59       GLint ymax = MAX2(0, ctx->Scissor.Y + ctx->Scissor.Height);
     60 
     61       if (ctx->Scissor.X > (GLint)scissor.minx)
     62          scissor.minx = ctx->Scissor.X;
     63       if (ctx->Scissor.Y > (GLint)scissor.miny)
     64          scissor.miny = ctx->Scissor.Y;
     65 
     66       if (xmax < (GLint) scissor.maxx)
     67          scissor.maxx = xmax;
     68       if (ymax < (GLint) scissor.maxy)
     69          scissor.maxy = ymax;
     70 
     71       /* check for null space */
     72       if (scissor.minx >= scissor.maxx || scissor.miny >= scissor.maxy)
     73          scissor.minx = scissor.miny = scissor.maxx = scissor.maxy = 0;
     74    }
     75 
     76    /* Now invert Y if needed.
     77     * Gallium drivers use the convention Y=0=top for surfaces.
     78     */
     79    if (st_fb_orientation(fb) == Y_0_TOP) {
     80       miny = fb->Height - scissor.maxy;
     81       maxy = fb->Height - scissor.miny;
     82       scissor.miny = miny;
     83       scissor.maxy = maxy;
     84    }
     85 
     86    if (memcmp(&scissor, &st->state.scissor, sizeof(scissor)) != 0) {
     87       /* state has changed */
     88       st->state.scissor = scissor;  /* struct copy */
     89       st->pipe->set_scissor_state(st->pipe, &scissor); /* activate */
     90    }
     91 }
     92 
     93 
     94 const struct st_tracked_state st_update_scissor = {
     95    "st_update_scissor",					/* name */
     96    {							/* dirty */
     97       (_NEW_SCISSOR | _NEW_BUFFERS),			/* mesa */
     98       0,						/* st */
     99    },
    100    update_scissor					/* update */
    101 };
    102