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1 /*
2  * Mesa 3-D graphics library
3  *
4  * Copyright (C) 2009  VMware, Inc.  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 "Software"),
8  * to deal in the Software without restriction, including without limitation
9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10  * and/or sell copies of the Software, and to permit persons to whom the
11  * Software is furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included
14  * in all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22  * OTHER DEALINGS IN THE SOFTWARE.
23  */
24 
25 
26 /**
27  * \file viewport.c
28  * glViewport and glDepthRange functions.
29  */
30 
31 
32 #include "context.h"
33 #include "enums.h"
34 #include "macros.h"
35 #include "mtypes.h"
36 #include "viewport.h"
37 
38 static void
clamp_viewport(struct gl_context * ctx,GLfloat * x,GLfloat * y,GLfloat * width,GLfloat * height)39 clamp_viewport(struct gl_context *ctx, GLfloat *x, GLfloat *y,
40                GLfloat *width, GLfloat *height)
41 {
42    /* clamp width and height to the implementation dependent range */
43    *width  = MIN2(*width, (GLfloat) ctx->Const.MaxViewportWidth);
44    *height = MIN2(*height, (GLfloat) ctx->Const.MaxViewportHeight);
45 
46    /* The GL_ARB_viewport_array spec says:
47     *
48     *     "The location of the viewport's bottom-left corner, given by (x,y),
49     *     are clamped to be within the implementation-dependent viewport
50     *     bounds range.  The viewport bounds range [min, max] tuple may be
51     *     determined by calling GetFloatv with the symbolic constant
52     *     VIEWPORT_BOUNDS_RANGE (see section 6.1)."
53     */
54    if (_mesa_has_ARB_viewport_array(ctx) ||
55        _mesa_has_OES_viewport_array(ctx)) {
56       *x = CLAMP(*x,
57                  ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
58       *y = CLAMP(*y,
59                  ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
60    }
61 }
62 
63 static void
set_viewport_no_notify(struct gl_context * ctx,unsigned idx,GLfloat x,GLfloat y,GLfloat width,GLfloat height)64 set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
65                        GLfloat x, GLfloat y,
66                        GLfloat width, GLfloat height)
67 {
68    if (ctx->ViewportArray[idx].X == x &&
69        ctx->ViewportArray[idx].Width == width &&
70        ctx->ViewportArray[idx].Y == y &&
71        ctx->ViewportArray[idx].Height == height)
72       return;
73 
74    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewViewport ? 0 : _NEW_VIEWPORT);
75    ctx->NewDriverState |= ctx->DriverFlags.NewViewport;
76 
77    ctx->ViewportArray[idx].X = x;
78    ctx->ViewportArray[idx].Width = width;
79    ctx->ViewportArray[idx].Y = y;
80    ctx->ViewportArray[idx].Height = height;
81 }
82 
83 struct gl_viewport_inputs {
84    GLfloat X, Y;                /**< position */
85    GLfloat Width, Height;       /**< size */
86 };
87 
88 struct gl_depthrange_inputs {
89    GLdouble Near, Far;          /**< Depth buffer range */
90 };
91 
92 static void
viewport(struct gl_context * ctx,GLint x,GLint y,GLsizei width,GLsizei height)93 viewport(struct gl_context *ctx, GLint x, GLint y, GLsizei width,
94          GLsizei height)
95 {
96    struct gl_viewport_inputs input = { x, y, width, height };
97 
98    /* Clamp the viewport to the implementation dependent values. */
99    clamp_viewport(ctx, &input.X, &input.Y, &input.Width, &input.Height);
100 
101    /* The GL_ARB_viewport_array spec says:
102     *
103     *     "Viewport sets the parameters for all viewports to the same values
104     *     and is equivalent (assuming no errors are generated) to:
105     *
106     *     for (uint i = 0; i < MAX_VIEWPORTS; i++)
107     *         ViewportIndexedf(i, 1, (float)x, (float)y, (float)w, (float)h);"
108     *
109     * Set all of the viewports supported by the implementation, but only
110     * signal the driver once at the end.
111     */
112    for (unsigned i = 0; i < ctx->Const.MaxViewports; i++)
113       set_viewport_no_notify(ctx, i, input.X, input.Y, input.Width, input.Height);
114 
115    if (ctx->Driver.Viewport)
116       ctx->Driver.Viewport(ctx);
117 }
118 
119 /**
120  * Set the viewport.
121  * \sa Called via glViewport() or display list execution.
122  *
123  * Flushes the vertices and calls _mesa_set_viewport() with the given
124  * parameters.
125  */
126 void GLAPIENTRY
_mesa_Viewport_no_error(GLint x,GLint y,GLsizei width,GLsizei height)127 _mesa_Viewport_no_error(GLint x, GLint y, GLsizei width, GLsizei height)
128 {
129    GET_CURRENT_CONTEXT(ctx);
130    viewport(ctx, x, y, width, height);
131 }
132 
133 void GLAPIENTRY
_mesa_Viewport(GLint x,GLint y,GLsizei width,GLsizei height)134 _mesa_Viewport(GLint x, GLint y, GLsizei width, GLsizei height)
135 {
136    GET_CURRENT_CONTEXT(ctx);
137 
138    if (MESA_VERBOSE & VERBOSE_API)
139       _mesa_debug(ctx, "glViewport %d %d %d %d\n", x, y, width, height);
140 
141    if (width < 0 || height < 0) {
142       _mesa_error(ctx,  GL_INVALID_VALUE,
143                    "glViewport(%d, %d, %d, %d)", x, y, width, height);
144       return;
145    }
146 
147    viewport(ctx, x, y, width, height);
148 }
149 
150 
151 /**
152  * Set new viewport parameters and update derived state.
153  * Usually called from _mesa_Viewport().
154  *
155  * \param ctx GL context.
156  * \param idx    Index of the viewport to be updated.
157  * \param x, y coordinates of the lower left corner of the viewport rectangle.
158  * \param width width of the viewport rectangle.
159  * \param height height of the viewport rectangle.
160  */
161 void
_mesa_set_viewport(struct gl_context * ctx,unsigned idx,GLfloat x,GLfloat y,GLfloat width,GLfloat height)162 _mesa_set_viewport(struct gl_context *ctx, unsigned idx, GLfloat x, GLfloat y,
163                     GLfloat width, GLfloat height)
164 {
165    clamp_viewport(ctx, &x, &y, &width, &height);
166    set_viewport_no_notify(ctx, idx, x, y, width, height);
167 
168    if (ctx->Driver.Viewport)
169       ctx->Driver.Viewport(ctx);
170 }
171 
172 static void
viewport_array(struct gl_context * ctx,GLuint first,GLsizei count,struct gl_viewport_inputs * inputs)173 viewport_array(struct gl_context *ctx, GLuint first, GLsizei count,
174                struct gl_viewport_inputs *inputs)
175 {
176    for (GLsizei i = 0; i < count; i++) {
177       clamp_viewport(ctx, &inputs[i].X, &inputs[i].Y,
178                      &inputs[i].Width, &inputs[i].Height);
179 
180       set_viewport_no_notify(ctx, i + first, inputs[i].X, inputs[i].Y,
181                              inputs[i].Width, inputs[i].Height);
182    }
183 
184    if (ctx->Driver.Viewport)
185       ctx->Driver.Viewport(ctx);
186 }
187 
188 void GLAPIENTRY
_mesa_ViewportArrayv_no_error(GLuint first,GLsizei count,const GLfloat * v)189 _mesa_ViewportArrayv_no_error(GLuint first, GLsizei count, const GLfloat *v)
190 {
191    GET_CURRENT_CONTEXT(ctx);
192 
193    struct gl_viewport_inputs *p = (struct gl_viewport_inputs *)v;
194    viewport_array(ctx, first, count, p);
195 }
196 
197 void GLAPIENTRY
_mesa_ViewportArrayv(GLuint first,GLsizei count,const GLfloat * v)198 _mesa_ViewportArrayv(GLuint first, GLsizei count, const GLfloat *v)
199 {
200    int i;
201    struct gl_viewport_inputs *p = (struct gl_viewport_inputs *)v;
202    GET_CURRENT_CONTEXT(ctx);
203 
204    if (MESA_VERBOSE & VERBOSE_API)
205       _mesa_debug(ctx, "glViewportArrayv %d %d\n", first, count);
206 
207    if ((first + count) > ctx->Const.MaxViewports) {
208       _mesa_error(ctx, GL_INVALID_VALUE,
209                   "glViewportArrayv: first (%d) + count (%d) > MaxViewports "
210                   "(%d)",
211                   first, count, ctx->Const.MaxViewports);
212       return;
213    }
214 
215    /* Verify width & height */
216    for (i = 0; i < count; i++) {
217       if (p[i].Width < 0 || p[i].Height < 0) {
218          _mesa_error(ctx, GL_INVALID_VALUE,
219                      "glViewportArrayv: index (%d) width or height < 0 "
220                      "(%f, %f)",
221                      i + first, p[i].Width, p[i].Height);
222          return;
223       }
224    }
225 
226    viewport_array(ctx, first, count, p);
227 }
228 
229 static void
viewport_indexed_err(struct gl_context * ctx,GLuint index,GLfloat x,GLfloat y,GLfloat w,GLfloat h,const char * function)230 viewport_indexed_err(struct gl_context *ctx, GLuint index, GLfloat x, GLfloat y,
231                      GLfloat w, GLfloat h, const char *function)
232 {
233    if (MESA_VERBOSE & VERBOSE_API)
234       _mesa_debug(ctx, "%s(%d, %f, %f, %f, %f)\n",
235                   function, index, x, y, w, h);
236 
237    if (index >= ctx->Const.MaxViewports) {
238       _mesa_error(ctx, GL_INVALID_VALUE,
239                   "%s: index (%d) >= MaxViewports (%d)",
240                   function, index, ctx->Const.MaxViewports);
241       return;
242    }
243 
244    /* Verify width & height */
245    if (w < 0 || h < 0) {
246       _mesa_error(ctx, GL_INVALID_VALUE,
247                   "%s: index (%d) width or height < 0 (%f, %f)",
248                   function, index, w, h);
249       return;
250    }
251 
252    _mesa_set_viewport(ctx, index, x, y, w, h);
253 }
254 
255 void GLAPIENTRY
_mesa_ViewportIndexedf_no_error(GLuint index,GLfloat x,GLfloat y,GLfloat w,GLfloat h)256 _mesa_ViewportIndexedf_no_error(GLuint index, GLfloat x, GLfloat y,
257                                 GLfloat w, GLfloat h)
258 {
259    GET_CURRENT_CONTEXT(ctx);
260    _mesa_set_viewport(ctx, index, x, y, w, h);
261 }
262 
263 void GLAPIENTRY
_mesa_ViewportIndexedf(GLuint index,GLfloat x,GLfloat y,GLfloat w,GLfloat h)264 _mesa_ViewportIndexedf(GLuint index, GLfloat x, GLfloat y,
265                        GLfloat w, GLfloat h)
266 {
267    GET_CURRENT_CONTEXT(ctx);
268    viewport_indexed_err(ctx, index, x, y, w, h, "glViewportIndexedf");
269 }
270 
271 void GLAPIENTRY
_mesa_ViewportIndexedfv_no_error(GLuint index,const GLfloat * v)272 _mesa_ViewportIndexedfv_no_error(GLuint index, const GLfloat *v)
273 {
274    GET_CURRENT_CONTEXT(ctx);
275    _mesa_set_viewport(ctx, index, v[0], v[1], v[2], v[3]);
276 }
277 
278 void GLAPIENTRY
_mesa_ViewportIndexedfv(GLuint index,const GLfloat * v)279 _mesa_ViewportIndexedfv(GLuint index, const GLfloat *v)
280 {
281    GET_CURRENT_CONTEXT(ctx);
282    viewport_indexed_err(ctx, index, v[0], v[1], v[2], v[3],
283                         "glViewportIndexedfv");
284 }
285 
286 static void
set_depth_range_no_notify(struct gl_context * ctx,unsigned idx,GLclampd nearval,GLclampd farval)287 set_depth_range_no_notify(struct gl_context *ctx, unsigned idx,
288                           GLclampd nearval, GLclampd farval)
289 {
290    if (ctx->ViewportArray[idx].Near == nearval &&
291        ctx->ViewportArray[idx].Far == farval)
292       return;
293 
294    /* The depth range is needed by program state constants. */
295    FLUSH_VERTICES(ctx, _NEW_VIEWPORT);
296    ctx->NewDriverState |= ctx->DriverFlags.NewViewport;
297 
298    ctx->ViewportArray[idx].Near = CLAMP(nearval, 0.0, 1.0);
299    ctx->ViewportArray[idx].Far = CLAMP(farval, 0.0, 1.0);
300 }
301 
302 void
_mesa_set_depth_range(struct gl_context * ctx,unsigned idx,GLclampd nearval,GLclampd farval)303 _mesa_set_depth_range(struct gl_context *ctx, unsigned idx,
304                       GLclampd nearval, GLclampd farval)
305 {
306    set_depth_range_no_notify(ctx, idx, nearval, farval);
307 
308    if (ctx->Driver.DepthRange)
309       ctx->Driver.DepthRange(ctx);
310 }
311 
312 /**
313  * Called by glDepthRange
314  *
315  * \param nearval  specifies the Z buffer value which should correspond to
316  *                 the near clip plane
317  * \param farval  specifies the Z buffer value which should correspond to
318  *                the far clip plane
319  */
320 void GLAPIENTRY
_mesa_DepthRange(GLclampd nearval,GLclampd farval)321 _mesa_DepthRange(GLclampd nearval, GLclampd farval)
322 {
323    unsigned i;
324    GET_CURRENT_CONTEXT(ctx);
325 
326    if (MESA_VERBOSE&VERBOSE_API)
327       _mesa_debug(ctx, "glDepthRange %f %f\n", nearval, farval);
328 
329    /* The GL_ARB_viewport_array spec says:
330     *
331     *     "DepthRange sets the depth range for all viewports to the same
332     *     values and is equivalent (assuming no errors are generated) to:
333     *
334     *     for (uint i = 0; i < MAX_VIEWPORTS; i++)
335     *         DepthRangeIndexed(i, n, f);"
336     *
337     * Set the depth range for all of the viewports supported by the
338     * implementation, but only signal the driver once at the end.
339     */
340    for (i = 0; i < ctx->Const.MaxViewports; i++)
341       set_depth_range_no_notify(ctx, i, nearval, farval);
342 
343    if (ctx->Driver.DepthRange) {
344       ctx->Driver.DepthRange(ctx);
345    }
346 }
347 
348 void GLAPIENTRY
_mesa_DepthRangef(GLclampf nearval,GLclampf farval)349 _mesa_DepthRangef(GLclampf nearval, GLclampf farval)
350 {
351    _mesa_DepthRange(nearval, farval);
352 }
353 
354 /**
355  * Update a range DepthRange values
356  *
357  * \param first   starting array index
358  * \param count   count of DepthRange items to update
359  * \param v       pointer to memory containing
360  *                GLclampd near and far clip-plane values
361  */
362 static ALWAYS_INLINE void
depth_range_arrayv(struct gl_context * ctx,GLuint first,GLsizei count,const struct gl_depthrange_inputs * const inputs)363 depth_range_arrayv(struct gl_context *ctx, GLuint first, GLsizei count,
364                    const struct gl_depthrange_inputs *const inputs)
365 {
366    for (GLsizei i = 0; i < count; i++)
367       set_depth_range_no_notify(ctx, i + first, inputs[i].Near, inputs[i].Far);
368 
369    if (ctx->Driver.DepthRange)
370       ctx->Driver.DepthRange(ctx);
371 }
372 
373 void GLAPIENTRY
_mesa_DepthRangeArrayv_no_error(GLuint first,GLsizei count,const GLclampd * v)374 _mesa_DepthRangeArrayv_no_error(GLuint first, GLsizei count, const GLclampd *v)
375 {
376    GET_CURRENT_CONTEXT(ctx);
377 
378    const struct gl_depthrange_inputs *const p =
379       (struct gl_depthrange_inputs *)v;
380    depth_range_arrayv(ctx, first, count, p);
381 }
382 
383 void GLAPIENTRY
_mesa_DepthRangeArrayv(GLuint first,GLsizei count,const GLclampd * v)384 _mesa_DepthRangeArrayv(GLuint first, GLsizei count, const GLclampd *v)
385 {
386    const struct gl_depthrange_inputs *const p =
387       (struct gl_depthrange_inputs *) v;
388    GET_CURRENT_CONTEXT(ctx);
389 
390    if (MESA_VERBOSE & VERBOSE_API)
391       _mesa_debug(ctx, "glDepthRangeArrayv %d %d\n", first, count);
392 
393    if ((first + count) > ctx->Const.MaxViewports) {
394       _mesa_error(ctx, GL_INVALID_VALUE,
395                   "glDepthRangev: first (%d) + count (%d) >= MaxViewports (%d)",
396                   first, count, ctx->Const.MaxViewports);
397       return;
398    }
399 
400    depth_range_arrayv(ctx, first, count, p);
401 }
402 
403 void GLAPIENTRY
_mesa_DepthRangeArrayfvOES(GLuint first,GLsizei count,const GLfloat * v)404 _mesa_DepthRangeArrayfvOES(GLuint first, GLsizei count, const GLfloat *v)
405 {
406    int i;
407    GET_CURRENT_CONTEXT(ctx);
408 
409    if (MESA_VERBOSE & VERBOSE_API)
410       _mesa_debug(ctx, "glDepthRangeArrayfv %d %d\n", first, count);
411 
412    if ((first + count) > ctx->Const.MaxViewports) {
413       _mesa_error(ctx, GL_INVALID_VALUE,
414                   "glDepthRangeArrayfv: first (%d) + count (%d) >= MaxViewports (%d)",
415                   first, count, ctx->Const.MaxViewports);
416       return;
417    }
418 
419    for (i = 0; i < count; i++)
420       set_depth_range_no_notify(ctx, i + first, v[i * 2], v[i * 2 + 1]);
421 
422    if (ctx->Driver.DepthRange)
423       ctx->Driver.DepthRange(ctx);
424 }
425 
426 /**
427  * Update a single DepthRange
428  *
429  * \param index    array index to update
430  * \param nearval  specifies the Z buffer value which should correspond to
431  *                 the near clip plane
432  * \param farval   specifies the Z buffer value which should correspond to
433  *                 the far clip plane
434  */
435 void GLAPIENTRY
_mesa_DepthRangeIndexed_no_error(GLuint index,GLclampd nearval,GLclampd farval)436 _mesa_DepthRangeIndexed_no_error(GLuint index, GLclampd nearval,
437                                  GLclampd farval)
438 {
439    GET_CURRENT_CONTEXT(ctx);
440    _mesa_set_depth_range(ctx, index, nearval, farval);
441 }
442 
443 
444 void GLAPIENTRY
_mesa_DepthRangeIndexed(GLuint index,GLclampd nearval,GLclampd farval)445 _mesa_DepthRangeIndexed(GLuint index, GLclampd nearval, GLclampd farval)
446 {
447    GET_CURRENT_CONTEXT(ctx);
448 
449    if (MESA_VERBOSE & VERBOSE_API)
450       _mesa_debug(ctx, "glDepthRangeIndexed(%d, %f, %f)\n",
451                   index, nearval, farval);
452 
453    if (index >= ctx->Const.MaxViewports) {
454       _mesa_error(ctx, GL_INVALID_VALUE,
455                   "glDepthRangeIndexed: index (%d) >= MaxViewports (%d)",
456                   index, ctx->Const.MaxViewports);
457       return;
458    }
459 
460    _mesa_set_depth_range(ctx, index, nearval, farval);
461 }
462 
463 void GLAPIENTRY
_mesa_DepthRangeIndexedfOES(GLuint index,GLfloat nearval,GLfloat farval)464 _mesa_DepthRangeIndexedfOES(GLuint index, GLfloat nearval, GLfloat farval)
465 {
466    _mesa_DepthRangeIndexed(index, nearval, farval);
467 }
468 
469 /**
470  * Initialize the context viewport attribute group.
471  * \param ctx  the GL context.
472  */
_mesa_init_viewport(struct gl_context * ctx)473 void _mesa_init_viewport(struct gl_context *ctx)
474 {
475    unsigned i;
476 
477    ctx->Transform.ClipOrigin = GL_LOWER_LEFT;
478    ctx->Transform.ClipDepthMode = GL_NEGATIVE_ONE_TO_ONE;
479 
480    /* Note: ctx->Const.MaxViewports may not have been set by the driver yet,
481     * so just initialize all of them.
482     */
483    for (i = 0; i < MAX_VIEWPORTS; i++) {
484       /* Viewport group */
485       ctx->ViewportArray[i].X = 0;
486       ctx->ViewportArray[i].Y = 0;
487       ctx->ViewportArray[i].Width = 0;
488       ctx->ViewportArray[i].Height = 0;
489       ctx->ViewportArray[i].Near = 0.0;
490       ctx->ViewportArray[i].Far = 1.0;
491    }
492 }
493 
494 
495 static ALWAYS_INLINE void
clip_control(struct gl_context * ctx,GLenum origin,GLenum depth,bool no_error)496 clip_control(struct gl_context *ctx, GLenum origin, GLenum depth, bool no_error)
497 {
498    if (ctx->Transform.ClipOrigin == origin &&
499        ctx->Transform.ClipDepthMode == depth)
500       return;
501 
502    if (!no_error &&
503        origin != GL_LOWER_LEFT && origin != GL_UPPER_LEFT) {
504       _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
505       return;
506    }
507 
508    if (!no_error &&
509        depth != GL_NEGATIVE_ONE_TO_ONE && depth != GL_ZERO_TO_ONE) {
510       _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
511       return;
512    }
513 
514    /* Affects transform state and the viewport transform */
515    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewClipControl ? 0 :
516                   _NEW_TRANSFORM | _NEW_VIEWPORT);
517    ctx->NewDriverState |= ctx->DriverFlags.NewClipControl;
518 
519    if (ctx->Transform.ClipOrigin != origin) {
520       ctx->Transform.ClipOrigin = origin;
521 
522       /* Affects the winding order of the front face. */
523       if (ctx->DriverFlags.NewPolygonState)
524          ctx->NewDriverState |= ctx->DriverFlags.NewPolygonState;
525       else
526          ctx->NewState |= _NEW_POLYGON;
527 
528       if (ctx->Driver.FrontFace)
529          ctx->Driver.FrontFace(ctx, ctx->Polygon.FrontFace);
530    }
531 
532    if (ctx->Transform.ClipDepthMode != depth) {
533       ctx->Transform.ClipDepthMode = depth;
534 
535       if (ctx->Driver.DepthRange)
536          ctx->Driver.DepthRange(ctx);
537    }
538 }
539 
540 
541 void GLAPIENTRY
_mesa_ClipControl_no_error(GLenum origin,GLenum depth)542 _mesa_ClipControl_no_error(GLenum origin, GLenum depth)
543 {
544    GET_CURRENT_CONTEXT(ctx);
545    clip_control(ctx, origin, depth, true);
546 }
547 
548 
549 void GLAPIENTRY
_mesa_ClipControl(GLenum origin,GLenum depth)550 _mesa_ClipControl(GLenum origin, GLenum depth)
551 {
552    GET_CURRENT_CONTEXT(ctx);
553 
554    if (MESA_VERBOSE & VERBOSE_API)
555       _mesa_debug(ctx, "glClipControl(%s, %s)\n",
556 	          _mesa_enum_to_string(origin),
557                   _mesa_enum_to_string(depth));
558 
559    ASSERT_OUTSIDE_BEGIN_END(ctx);
560 
561    if (!ctx->Extensions.ARB_clip_control) {
562       _mesa_error(ctx, GL_INVALID_OPERATION, "glClipControl");
563       return;
564    }
565 
566    clip_control(ctx, origin, depth, false);
567 }
568 
569 /**
570  * Computes the scaling and the translation part of the
571  * viewport transform matrix of the \param i-th viewport
572  * and writes that into \param scale and \param translate.
573  */
574 void
_mesa_get_viewport_xform(struct gl_context * ctx,unsigned i,float scale[3],float translate[3])575 _mesa_get_viewport_xform(struct gl_context *ctx, unsigned i,
576                          float scale[3], float translate[3])
577 {
578    float x = ctx->ViewportArray[i].X;
579    float y = ctx->ViewportArray[i].Y;
580    float half_width = 0.5f * ctx->ViewportArray[i].Width;
581    float half_height = 0.5f * ctx->ViewportArray[i].Height;
582    double n = ctx->ViewportArray[i].Near;
583    double f = ctx->ViewportArray[i].Far;
584 
585    scale[0] = half_width;
586    translate[0] = half_width + x;
587    if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT) {
588       scale[1] = -half_height;
589    } else {
590       scale[1] = half_height;
591    }
592    translate[1] = half_height + y;
593 
594    if (ctx->Transform.ClipDepthMode == GL_NEGATIVE_ONE_TO_ONE) {
595       scale[2] = 0.5 * (f - n);
596       translate[2] = 0.5 * (n + f);
597    } else {
598       scale[2] = f - n;
599       translate[2] = n;
600    }
601 }
602