text: /*
   * Mesa 3-D graphics library
   * Version:  7.9
   *
   * Copyright (C) 2010 LunarG Inc.
   *
   * 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
   * THE AUTHORS OR COPYRIGHT HOLDERS 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.
   *
   * Authors:
   *    Chia-I Wu <olv@lunarg.com>
   */
  
  #include "state_tracker/st_gl_api.h"
  
  #include "pipe/p_context.h"
  #include "pipe/p_screen.h"
  #include "util/u_format.h"
  #include "util/u_pointer.h"
  #include "util/u_inlines.h"
  #include "util/u_atomic.h"
  
  #include "main/mtypes.h"
  #include "main/context.h"
  #include "main/texobj.h"
  #include "main/teximage.h"
  #include "main/texstate.h"
  #include "main/texfetch.h"
  #include "main/framebuffer.h"
  #include "main/fbobject.h"
  #include "main/renderbuffer.h"
  #include "main/version.h"
  #include "st_texture.h"
  
  #include "st_context.h"
  #include "st_format.h"
  #include "st_cb_fbo.h"
  #include "st_cb_flush.h"
  #include "st_manager.h"
  
  /**
   * Cast wrapper to convert a GLframebuffer to an st_framebuffer.
   * Return NULL if the GLframebuffer is a user-created framebuffer.
   * We'll only return non-null for window system framebuffers.
   * Note that this function may fail.
   */
  static INLINE struct st_framebuffer *
  st_ws_framebuffer(GLframebuffer *fb)
  {
     /* FBO cannot be casted.  See st_new_framebuffer */
     return (struct st_framebuffer *) ((fb && !fb->Name) ? fb : NULL);
  }
  
  /**
   * Map an attachment to a buffer index.
   */
  static INLINE gl_buffer_index
  attachment_to_buffer_index(enum st_attachment_type statt)
  {
     gl_buffer_index index;
  
     switch (statt) {
     case ST_ATTACHMENT_FRONT_LEFT:
        index = BUFFER_FRONT_LEFT;
        break;
     case ST_ATTACHMENT_BACK_LEFT:
        index = BUFFER_BACK_LEFT;
        break;
     case ST_ATTACHMENT_FRONT_RIGHT:
        index = BUFFER_FRONT_RIGHT;
        break;
     case ST_ATTACHMENT_BACK_RIGHT:
        index = BUFFER_BACK_RIGHT;
        break;
     case ST_ATTACHMENT_DEPTH_STENCIL:
        index = BUFFER_DEPTH;
        break;
     case ST_ATTACHMENT_ACCUM:
        index = BUFFER_ACCUM;
        break;
     case ST_ATTACHMENT_SAMPLE:
     default:
        index = BUFFER_COUNT;
        break;
     }
  
     return index;
  }
  
  /**
   * Map a buffer index to an attachment.
   */
  static INLINE enum st_attachment_type
  buffer_index_to_attachment(gl_buffer_index index)
  {
     enum st_attachment_type statt;
  
     switch (index) {
     case BUFFER_FRONT_LEFT:
        statt = ST_ATTACHMENT_FRONT_LEFT;
        break;
     case BUFFER_BACK_LEFT:
        statt = ST_ATTACHMENT_BACK_LEFT;
        break;
     case BUFFER_FRONT_RIGHT:
        statt = ST_ATTACHMENT_FRONT_RIGHT;
        break;
     case BUFFER_BACK_RIGHT:
        statt = ST_ATTACHMENT_BACK_RIGHT;
        break;
     case BUFFER_DEPTH:
        statt = ST_ATTACHMENT_DEPTH_STENCIL;
        break;
     case BUFFER_ACCUM:
        statt = ST_ATTACHMENT_ACCUM;
        break;
     default:
        statt = ST_ATTACHMENT_INVALID;
        break;
     }
  
     return statt;
  }
  
  /**
   * Validate a framebuffer to make sure up-to-date pipe_textures are used.
   */
  static void
  st_framebuffer_validate(struct st_framebuffer *stfb, struct st_context *st)
  {
     struct pipe_screen *screen = st->pipe->screen;
     struct pipe_resource *textures[ST_ATTACHMENT_COUNT];
     uint width, height;
     unsigned i;
     boolean changed = FALSE;
  
     if (!p_atomic_read(&stfb->revalidate))
        return;
  
     /* validate the fb */
     if (!stfb->iface->validate(stfb->iface, stfb->statts, stfb->num_statts, textures))
        return;
  
     width = stfb->Base.Width;
     height = stfb->Base.Height;
  
     for (i = 0; i < stfb->num_statts; i++) {
        struct st_renderbuffer *strb;
        struct pipe_surface *ps;
        gl_buffer_index idx;
  
        if (!textures[i])
           continue;
  
        idx = attachment_to_buffer_index(stfb->statts[i]);
        if (idx >= BUFFER_COUNT) {
           pipe_resource_reference(&textures[i], NULL);
           continue;
        }
  
        strb = st_renderbuffer(stfb->Base.Attachment[idx].Renderbuffer);
        assert(strb);
        if (strb->texture == textures[i]) {
           pipe_resource_reference(&textures[i], NULL);
           continue;
        }
  
        ps = screen->get_tex_surface(screen, textures[i], 0, 0, 0,
  				   PIPE_BIND_RENDER_TARGET);
        if (ps) {
           pipe_surface_reference(&strb->surface, ps);
           pipe_resource_reference(&strb->texture, ps->texture);
           /* ownership transfered */
           pipe_surface_reference(&ps, NULL);
  
           changed = TRUE;
  
           strb->Base.Width = strb->surface->width;
           strb->Base.Height = strb->surface->height;
  
           width = strb->Base.Width;
           height = strb->Base.Height;
        }
  
        pipe_resource_reference(&textures[i], NULL);
     }
  
     if (changed) {
        st->dirty.st |= ST_NEW_FRAMEBUFFER;
        _mesa_resize_framebuffer(st->ctx, &stfb->Base, width, height);
  
        assert(stfb->Base.Width == width);
        assert(stfb->Base.Height == height);
     }
  
     p_atomic_set(&stfb->revalidate, FALSE);
  }
  
  /**
   * Update the attachments to validate by looping the existing renderbuffers.
   */
  static void
  st_framebuffer_update_attachments(struct st_framebuffer *stfb)
  {
     gl_buffer_index idx;
  
     stfb->num_statts = 0;
     for (idx = 0; idx < BUFFER_COUNT; idx++) {
        struct st_renderbuffer *strb;
        enum st_attachment_type statt;
  
        strb = st_renderbuffer(stfb->Base.Attachment[idx].Renderbuffer);
        if (!strb || strb->software)
           continue;
  
        statt = buffer_index_to_attachment(idx);
        if (statt != ST_ATTACHMENT_INVALID &&
            st_visual_have_buffers(stfb->iface->visual, 1 << statt))
           stfb->statts[stfb->num_statts++] = statt;
     }
  
     p_atomic_set(&stfb->revalidate, TRUE);
  }
  
  /**
   * Add a renderbuffer to the framebuffer.
   */
  static boolean
  st_framebuffer_add_renderbuffer(struct st_framebuffer *stfb,
                                  gl_buffer_index idx)
  {
     struct gl_renderbuffer *rb;
     enum pipe_format format;
     int samples;
     boolean sw;
  
     if (!stfb->iface)
        return FALSE;
  
     /* do not distinguish depth/stencil buffers */
     if (idx == BUFFER_STENCIL)
        idx = BUFFER_DEPTH;
  
     switch (idx) {
     case BUFFER_DEPTH:
        format = stfb->iface->visual->depth_stencil_format;
        sw = FALSE;
        break;
     case BUFFER_ACCUM:
        format = stfb->iface->visual->accum_format;
        sw = TRUE;
        break;
     default:
        format = stfb->iface->visual->color_format;
        sw = FALSE;
        break;
     }
  
     if (format == PIPE_FORMAT_NONE)
        return FALSE;
  
     samples = stfb->iface->visual->samples;
     if (!samples)
        samples = st_get_msaa();
  
     rb = st_new_renderbuffer_fb(format, samples, sw);
     if (!rb)
        return FALSE;
  
     if (idx != BUFFER_DEPTH) {
        _mesa_add_renderbuffer(&stfb->Base, idx, rb);
     }
     else {
        if (util_format_get_component_bits(format, UTIL_FORMAT_COLORSPACE_ZS, 0))
           _mesa_add_renderbuffer(&stfb->Base, BUFFER_DEPTH, rb);
        if (util_format_get_component_bits(format, UTIL_FORMAT_COLORSPACE_ZS, 1))
           _mesa_add_renderbuffer(&stfb->Base, BUFFER_STENCIL, rb);
     }
  
     return TRUE;
  }
  
  /**
   * Intialize a __GLcontextModes from a visual.
   */
  static void
  st_visual_to_context_mode(const struct st_visual *visual,
                            __GLcontextModes *mode)
  {
     memset(mode, 0, sizeof(*mode));
  
     if (st_visual_have_buffers(visual, ST_ATTACHMENT_BACK_LEFT_MASK))
        mode->doubleBufferMode = GL_TRUE;
     if (st_visual_have_buffers(visual,
              ST_ATTACHMENT_FRONT_RIGHT_MASK | ST_ATTACHMENT_BACK_RIGHT_MASK))
        mode->stereoMode = GL_TRUE;
  
     if (visual->color_format != PIPE_FORMAT_NONE) {
        mode->rgbMode = GL_TRUE;
  
        mode->redBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 0);
        mode->greenBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 1);
        mode->blueBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 2);
        mode->alphaBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 3);
  
        mode->rgbBits = mode->redBits +
           mode->greenBits + mode->blueBits + mode->alphaBits;
     }
  
     if (visual->depth_stencil_format != PIPE_FORMAT_NONE) {
        mode->depthBits =
           util_format_get_component_bits(visual->depth_stencil_format,
                 UTIL_FORMAT_COLORSPACE_ZS, 0);
        mode->stencilBits =
           util_format_get_component_bits(visual->depth_stencil_format,
                 UTIL_FORMAT_COLORSPACE_ZS, 1);
  
        mode->haveDepthBuffer = mode->depthBits > 0;
        mode->haveStencilBuffer = mode->stencilBits > 0;
     }
  
     if (visual->accum_format != PIPE_FORMAT_NONE) {
        mode->haveAccumBuffer = GL_TRUE;
  
        mode->accumRedBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 0);
        mode->accumGreenBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 1);
        mode->accumBlueBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 2);
        mode->accumAlphaBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 3);
     }
  
     if (visual->samples) {
        mode->sampleBuffers = 1;
        mode->samples = visual->samples;
     }
  }
  
  /**
   * Determine the default draw or read buffer from a visual.
   */
  static void
  st_visual_to_default_buffer(const struct st_visual *visual,
                              GLenum *buffer, GLint *index)
  {
     enum st_attachment_type statt;
     GLenum buf;
     gl_buffer_index idx;
  
     statt = visual->render_buffer;
     /* do nothing if an invalid render buffer is specified */
     if (statt == ST_ATTACHMENT_INVALID ||
         !st_visual_have_buffers(visual, 1 << statt))
        return;
  
     switch (statt) {
     case ST_ATTACHMENT_FRONT_LEFT:
        buf = GL_FRONT_LEFT;
        idx = BUFFER_FRONT_LEFT;
        break;
     case ST_ATTACHMENT_BACK_LEFT:
        buf = GL_BACK_LEFT;
        idx = BUFFER_BACK_LEFT;
        break;
     case ST_ATTACHMENT_FRONT_RIGHT:
        buf = GL_FRONT_RIGHT;
        idx = BUFFER_FRONT_RIGHT;
        break;
     case ST_ATTACHMENT_BACK_RIGHT:
        buf = GL_BACK_RIGHT;
        idx = BUFFER_BACK_RIGHT;
        break;
     default:
        buf = GL_NONE;
        idx = BUFFER_COUNT;
        break;
     }
  
     if (buf != GL_NONE) {
        if (buffer)
           *buffer = buf;
        if (index)
           *index = idx;
     }
  }
  
  /**
   * Create a framebuffer from a manager interface.
   */
  static struct st_framebuffer *
  st_framebuffer_create(struct st_framebuffer_iface *stfbi)
  {
     struct st_framebuffer *stfb;
     __GLcontextModes mode;
     gl_buffer_index idx;
  
     stfb = CALLOC_STRUCT(st_framebuffer);
     if (!stfb)
        return NULL;
  
     /* for FBO-only context */
     if (!stfbi) {
        GLframebuffer *base = _mesa_get_incomplete_framebuffer();
  
        stfb->Base = *base;
  
        return stfb;
     }
  
     st_visual_to_context_mode(stfbi->visual, &mode);
     _mesa_initialize_window_framebuffer(&stfb->Base, &mode);
  
     /* modify the draw/read buffers of the fb */
     st_visual_to_default_buffer(stfbi->visual, &stfb->Base.ColorDrawBuffer[0],
           &stfb->Base._ColorDrawBufferIndexes[0]);
     st_visual_to_default_buffer(stfbi->visual, &stfb->Base.ColorReadBuffer,
           &stfb->Base._ColorReadBufferIndex);
  
     stfb->iface = stfbi;
  
     /* add the color buffer */
     idx = stfb->Base._ColorDrawBufferIndexes[0];
     if (!st_framebuffer_add_renderbuffer(stfb, idx)) {
        FREE(stfb);
        return NULL;
     }
  
     st_framebuffer_add_renderbuffer(stfb, BUFFER_DEPTH);
     st_framebuffer_add_renderbuffer(stfb, BUFFER_ACCUM);
  
     st_framebuffer_update_attachments(stfb);
  
     stfb->Base.Initialized = GL_TRUE;
  
     return stfb;
  }
  
  /**
   * Reference a framebuffer.
   */
  static void
  st_framebuffer_reference(struct st_framebuffer **ptr,
                           struct st_framebuffer *stfb)
  {
     GLframebuffer *fb = &stfb->Base;
     _mesa_reference_framebuffer((GLframebuffer **) ptr, fb);
  }
  
  static void
  st_context_notify_invalid_framebuffer(struct st_context_iface *stctxi,
                                        struct st_framebuffer_iface *stfbi)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct st_framebuffer *stfb;
  
     /* either draw or read winsys fb */
     stfb = st_ws_framebuffer(st->ctx->WinSysDrawBuffer);
     if (!stfb || stfb->iface != stfbi)
        stfb = st_ws_framebuffer(st->ctx->WinSysReadBuffer);
     assert(stfb && stfb->iface == stfbi);
  
     p_atomic_set(&stfb->revalidate, TRUE);
  }
  
  static void
  st_context_flush(struct st_context_iface *stctxi, unsigned flags,
                   struct pipe_fence_handle **fence)
  {
     struct st_context *st = (struct st_context *) stctxi;
     st_flush(st, flags, fence);
     if (flags & PIPE_FLUSH_RENDER_CACHE)
        st_manager_flush_frontbuffer(st);
  }
  
  static boolean
  st_context_teximage(struct st_context_iface *stctxi, enum st_texture_type target,
                      int level, enum pipe_format internal_format,
                      struct pipe_resource *tex, boolean mipmap)
  {
     struct st_context *st = (struct st_context *) stctxi;
     GLcontext *ctx = st->ctx;
     struct gl_texture_unit *texUnit = _mesa_get_current_tex_unit(ctx);
     struct gl_texture_object *texObj;
     struct gl_texture_image *texImage;
     struct st_texture_object *stObj;
     struct st_texture_image *stImage;
     GLenum internalFormat;
     GLuint width, height, depth;
  
     switch (target) {
     case ST_TEXTURE_1D:
        target = GL_TEXTURE_1D;
        break;
     case ST_TEXTURE_2D:
        target = GL_TEXTURE_2D;
        break;
     case ST_TEXTURE_3D:
        target = GL_TEXTURE_3D;
        break;
     case ST_TEXTURE_RECT:
        target = GL_TEXTURE_RECTANGLE_ARB;
        break;
     default:
        return FALSE;
        break;
     }
  
     texObj = _mesa_select_tex_object(ctx, texUnit, target);
     _mesa_lock_texture(ctx, texObj);
  
     stObj = st_texture_object(texObj);
     /* switch to surface based */
     if (!stObj->surface_based) {
        _mesa_clear_texture_object(ctx, texObj);
        stObj->surface_based = GL_TRUE;
     }
  
     texImage = _mesa_get_tex_image(ctx, texObj, target, level);
     stImage = st_texture_image(texImage);
     if (tex) {
        /*
         * XXX When internal_format and tex->format differ, st_finalize_texture
         * needs to allocate a new texture with internal_format and copy the
         * texture here into the new one.  It will result in surface_copy being
         * called on surfaces whose formats differ.
         *
         * To avoid that, internal_format is (wrongly) ignored here.  A sane fix
         * is to use a sampler view.
         */
        if (!st_sampler_compat_formats(tex->format, internal_format))
  	 internal_format = tex->format;
       
        if (util_format_get_component_bits(internal_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 3) > 0)
           internalFormat = GL_RGBA;
        else
           internalFormat = GL_RGB;
        _mesa_init_teximage_fields(ctx, target, texImage,
              tex->width0, tex->height0, 1, 0, internalFormat);
        texImage->TexFormat = st_ChooseTextureFormat(ctx, internalFormat,
              GL_RGBA, GL_UNSIGNED_BYTE);
        _mesa_set_fetch_functions(texImage, 2);
  
        width = tex->width0;
        height = tex->height0;
        depth = tex->depth0;
  
        /* grow the image size until we hit level = 0 */
        while (level > 0) {
           if (width != 1)
              width <<= 1;
           if (height != 1)
              height <<= 1;
           if (depth != 1)
              depth <<= 1;
           level--;
        }
     }
     else {
        _mesa_clear_texture_image(ctx, texImage);
        width = height = depth = 0;
     }
  
     pipe_resource_reference(&stImage->pt, tex);
     stObj->width0 = width;
     stObj->height0 = height;
     stObj->depth0 = depth;
  
     _mesa_dirty_texobj(ctx, texObj, GL_TRUE);
     _mesa_unlock_texture(ctx, texObj);
     
     return TRUE;
  }
  
  static void
  st_context_destroy(struct st_context_iface *stctxi)
  {
     struct st_context *st = (struct st_context *) stctxi;
     st_destroy_context(st);
  }
  
  static struct st_context_iface *
  st_api_create_context(struct st_api *stapi, struct st_manager *smapi,
                        const struct st_context_attribs *attribs,
                        struct st_context_iface *shared_stctxi)
  {
     struct st_context *shared_ctx = (struct st_context *) shared_stctxi;
     struct st_context *st;
     struct pipe_context *pipe;
     __GLcontextModes mode;
     gl_api api;
  
     if (!(stapi->profile_mask & (1 << attribs->profile)))
        return NULL;
  
     switch (attribs->profile) {
     case ST_PROFILE_DEFAULT:
        api = API_OPENGL;
        break;
     case ST_PROFILE_OPENGL_ES1:
        api = API_OPENGLES;
        break;
     case ST_PROFILE_OPENGL_ES2:
        api = API_OPENGLES2;
        break;
     case ST_PROFILE_OPENGL_CORE:
     default:
        return NULL;
        break;
     }
  
     pipe = smapi->screen->context_create(smapi->screen, NULL);
     if (!pipe)
        return NULL;
  
     st_visual_to_context_mode(&attribs->visual, &mode);
     st = st_create_context(api, pipe, &mode, shared_ctx);
     if (!st) {
        pipe->destroy(pipe);
        return NULL;
     }
  
     /* need to perform version check */
     if (attribs->major > 1 || attribs->minor > 0) {
        _mesa_compute_version(st->ctx);
  
        if (st->ctx->VersionMajor < attribs->major ||
            st->ctx->VersionMajor < attribs->minor) {
           st_destroy_context(st);
           return NULL;
        }
     }
  
     st->invalidate_on_gl_viewport =
        smapi->get_param(smapi, ST_MANAGER_BROKEN_INVALIDATE);
  
     st->iface.destroy = st_context_destroy;
     st->iface.notify_invalid_framebuffer =
        st_context_notify_invalid_framebuffer;
     st->iface.flush = st_context_flush;
     st->iface.teximage = st_context_teximage;
     st->iface.copy = NULL;
     st->iface.st_context_private = (void *) smapi;
  
     return &st->iface;
  }
  
  static boolean
  st_api_make_current(struct st_api *stapi, struct st_context_iface *stctxi,
                      struct st_framebuffer_iface *stdrawi,
                      struct st_framebuffer_iface *streadi)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct st_framebuffer *stdraw, *stread, *stfb;
     boolean ret;
  
     _glapi_check_multithread();
  
     if (st) {
        /* reuse/create the draw fb */
        stfb = st_ws_framebuffer(st->ctx->WinSysDrawBuffer);
        if (stfb && stfb->iface == stdrawi) {
           stdraw = NULL;
           st_framebuffer_reference(&stdraw, stfb);
        }
        else {
           stdraw = st_framebuffer_create(stdrawi);
        }
  
        /* reuse/create the read fb */
        stfb = st_ws_framebuffer(st->ctx->WinSysReadBuffer);
        if (!stfb || stfb->iface != streadi)
           stfb = stdraw;
        if (stfb && stfb->iface == streadi) {
           stread = NULL;
           st_framebuffer_reference(&stread, stfb);
        }
        else {
           stread = st_framebuffer_create(streadi);
        }
  
        if (stdraw && stread) {
           st_framebuffer_validate(stdraw, st);
           if (stread != stdraw)
              st_framebuffer_validate(stread, st);
  
           /* modify the draw/read buffers of the context */
           if (stdraw->iface) {
              st_visual_to_default_buffer(stdraw->iface->visual,
                    &st->ctx->Color.DrawBuffer[0], NULL);
           }
           if (stread->iface) {
              st_visual_to_default_buffer(stread->iface->visual,
                    &st->ctx->Pixel.ReadBuffer, NULL);
           }
  
           ret = _mesa_make_current(st->ctx, &stdraw->Base, &stread->Base);
        }
        else {
           ret = FALSE;
        }
  
        st_framebuffer_reference(&stdraw, NULL);
        st_framebuffer_reference(&stread, NULL);
     }
     else {
        ret = _mesa_make_current(NULL, NULL, NULL);
     }
  
     return ret;
  }
  
  static struct st_context_iface *
  st_api_get_current(struct st_api *stapi)
  {
     GET_CURRENT_CONTEXT(ctx);
     struct st_context *st = (ctx) ? ctx->st : NULL;
  
     return (st) ? &st->iface : NULL;
  }
  
  static st_proc_t
  st_api_get_proc_address(struct st_api *stapi, const char *procname)
  {
     return (st_proc_t) _glapi_get_proc_address(procname);
  }
  
  static void
  st_api_destroy(struct st_api *stapi)
  {
  }
  
  /**
   * Flush the front buffer if the current context renders to the front buffer.
   */
  void
  st_manager_flush_frontbuffer(struct st_context *st)
  {
     struct st_framebuffer *stfb = st_ws_framebuffer(st->ctx->DrawBuffer);
     struct st_renderbuffer *strb = NULL;
  
     if (stfb)
        strb = st_renderbuffer(stfb->Base.Attachment[BUFFER_FRONT_LEFT].Renderbuffer);
     if (!strb)
        return;
  
     /* never a dummy fb */
     assert(stfb->iface);
     stfb->iface->flush_front(stfb->iface, ST_ATTACHMENT_FRONT_LEFT);
  }
  
  /**
   * Return the surface of an EGLImage.
   */
  struct pipe_surface *
  st_manager_get_egl_image_surface(struct st_context *st,
                                   void *eglimg, unsigned usage)
  {
     struct st_manager *smapi =
        (struct st_manager *) st->iface.st_context_private;
     struct st_egl_image stimg;
     struct pipe_surface *ps;
  
     if (!smapi || !smapi->get_egl_image)
        return NULL;
  
     memset(&stimg, 0, sizeof(stimg));
     if (!smapi->get_egl_image(smapi, eglimg, &stimg))
        return NULL;
  
     ps = smapi->screen->get_tex_surface(smapi->screen,
           stimg.texture, stimg.face, stimg.level, stimg.zslice, usage);
     pipe_resource_reference(&stimg.texture, NULL);
  
     return ps;
  }
  
  /**
   * Re-validate the framebuffers.
   */
  void
  st_manager_validate_framebuffers(struct st_context *st)
  {
     struct st_framebuffer *stdraw = st_ws_framebuffer(st->ctx->DrawBuffer);
     struct st_framebuffer *stread = st_ws_framebuffer(st->ctx->ReadBuffer);
  
     if (stdraw)
        st_framebuffer_validate(stdraw, st);
     if (stread && stread != stdraw)
        st_framebuffer_validate(stread, st);
  }
  
  /**
   * Add a color renderbuffer on demand.
   */
  boolean
  st_manager_add_color_renderbuffer(struct st_context *st, GLframebuffer *fb,
                                    gl_buffer_index idx)
  {
     struct st_framebuffer *stfb = st_ws_framebuffer(fb);
  
     /* FBO */
     if (!stfb)
        return FALSE;
  
     if (stfb->Base.Attachment[idx].Renderbuffer)
        return TRUE;
  
     switch (idx) {
     case BUFFER_FRONT_LEFT:
     case BUFFER_BACK_LEFT:
     case BUFFER_FRONT_RIGHT:
     case BUFFER_BACK_RIGHT:
        break;
     default:
        return FALSE;
        break;
     }
  
     if (!st_framebuffer_add_renderbuffer(stfb, idx))
        return FALSE;
  
     st_framebuffer_update_attachments(stfb);
     st_invalidate_state(st->ctx, _NEW_BUFFERS);
  
     return TRUE;
  }
  
  static const struct st_api st_gl_api = {
     ST_API_OPENGL,
  #if FEATURE_GL
     ST_PROFILE_DEFAULT_MASK |
  #endif
  #if FEATURE_ES1
     ST_PROFILE_OPENGL_ES1_MASK |
  #endif
  #if FEATURE_ES2
     ST_PROFILE_OPENGL_ES2_MASK |
  #endif
     0,
     st_api_destroy,
     st_api_get_proc_address,
     st_api_create_context,
     st_api_make_current,
     st_api_get_current,
  };
  
  struct st_api *
  st_gl_api_create(void)
  {
     return (struct st_api *) &st_gl_api;
  }
  