src/mesa/state_tracker/st_atom_scissor.c

   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@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 };