Subversion Repositories Kolibri OS

/*

 * Mesa 3-D graphics library

 *

 * Copyright (C) 1999-2008  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

 * 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.

 */

/**

 * Functions for allocating/managing framebuffers and renderbuffers.

 * Also, routines for reading/writing renderbuffer data as ubytes,

 * ushorts, uints, etc.

 */

#include 

#include "glheader.h"

#include "imports.h"

#include "blend.h"

#include "buffers.h"

#include "context.h"

#include "enums.h"

#include "formats.h"

#include "macros.h"

#include "mtypes.h"

#include "fbobject.h"

#include "framebuffer.h"

#include "renderbuffer.h"

#include "texobj.h"

#include "glformats.h"

/**

 * Compute/set the _DepthMax field for the given framebuffer.

 * This value depends on the Z buffer resolution.

 */

static void

compute_depth_max(struct gl_framebuffer *fb)

{

   if (fb->Visual.depthBits == 0) {

      /* Special case.  Even if we don't have a depth buffer we need

       * good values for DepthMax for Z vertex transformation purposes

       * and for per-fragment fog computation.

       */

      fb->_DepthMax = (1 << 16) - 1;

   }

   else if (fb->Visual.depthBits < 32) {

      fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;

   }

   else {

      /* Special case since shift values greater than or equal to the

       * number of bits in the left hand expression's type are undefined.

       */

      fb->_DepthMax = 0xffffffff;

   }

   fb->_DepthMaxF = (GLfloat) fb->_DepthMax;

   /* Minimum resolvable depth value, for polygon offset */

   fb->_MRD = (GLfloat)1.0 / fb->_DepthMaxF;

}

/**

 * Create and initialize a gl_framebuffer object.

 * This is intended for creating _window_system_ framebuffers, not generic

 * framebuffer objects ala GL_EXT_framebuffer_object.

 *

 * \sa _mesa_new_framebuffer

 */

struct gl_framebuffer *

_mesa_create_framebuffer(const struct gl_config *visual)

{

   struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);

   assert(visual);

   if (fb) {

      _mesa_initialize_window_framebuffer(fb, visual);

   }

   return fb;

}

/**

 * Allocate a new gl_framebuffer object.

 * This is the default function for ctx->Driver.NewFramebuffer().

 * This is for allocating user-created framebuffers, not window-system

 * framebuffers!

 * \sa _mesa_create_framebuffer

 */

struct gl_framebuffer *

_mesa_new_framebuffer(struct gl_context *ctx, GLuint name)

{

   struct gl_framebuffer *fb;

   (void) ctx;

   assert(name != 0);

   fb = CALLOC_STRUCT(gl_framebuffer);

   if (fb) {

      _mesa_initialize_user_framebuffer(fb, name);

   }

   return fb;

}

/**

 * Initialize a gl_framebuffer object.  Typically used to initialize

 * window system-created framebuffers, not user-created framebuffers.

 * \sa _mesa_initialize_user_framebuffer

 */

void

_mesa_initialize_window_framebuffer(struct gl_framebuffer *fb,

				     const struct gl_config *visual)

{

   assert(fb);

   assert(visual);

   memset(fb, 0, sizeof(struct gl_framebuffer));

   mtx_init(&fb->Mutex, mtx_plain);

   fb->RefCount = 1;

   /* save the visual */

   fb->Visual = *visual;

   /* Init read/draw renderbuffer state */

   if (visual->doubleBufferMode) {

      fb->_NumColorDrawBuffers = 1;

      fb->ColorDrawBuffer[0] = GL_BACK;

      fb->_ColorDrawBufferIndexes[0] = BUFFER_BACK_LEFT;

      fb->ColorReadBuffer = GL_BACK;

      fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;

   }

   else {

      fb->_NumColorDrawBuffers = 1;

      fb->ColorDrawBuffer[0] = GL_FRONT;

      fb->_ColorDrawBufferIndexes[0] = BUFFER_FRONT_LEFT;

      fb->ColorReadBuffer = GL_FRONT;

      fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;

   }

   fb->Delete = _mesa_destroy_framebuffer;

   fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;

   fb->_AllColorBuffersFixedPoint = !visual->floatMode;

   fb->_HasSNormOrFloatColorBuffer = visual->floatMode;

   compute_depth_max(fb);

}

/**

 * Initialize a user-created gl_framebuffer object.

 * \sa _mesa_initialize_window_framebuffer

 */

void

_mesa_initialize_user_framebuffer(struct gl_framebuffer *fb, GLuint name)

{

   assert(fb);

   assert(name);

   memset(fb, 0, sizeof(struct gl_framebuffer));

   fb->Name = name;

   fb->RefCount = 1;

   fb->_NumColorDrawBuffers = 1;

   fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;

   fb->_ColorDrawBufferIndexes[0] = BUFFER_COLOR0;

   fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;

   fb->_ColorReadBufferIndex = BUFFER_COLOR0;

   fb->Delete = _mesa_destroy_framebuffer;

   mtx_init(&fb->Mutex, mtx_plain);

}

/**

 * Deallocate buffer and everything attached to it.

 * Typically called via the gl_framebuffer->Delete() method.

 */

void

_mesa_destroy_framebuffer(struct gl_framebuffer *fb)

{

   if (fb) {

      _mesa_free_framebuffer_data(fb);

      free(fb->Label);

      free(fb);

   }

}

/**

 * Free all the data hanging off the given gl_framebuffer, but don't free

 * the gl_framebuffer object itself.

 */

void

_mesa_free_framebuffer_data(struct gl_framebuffer *fb)

{

   GLuint i;

   assert(fb);

   assert(fb->RefCount == 0);

   mtx_destroy(&fb->Mutex);

   for (i = 0; i < BUFFER_COUNT; i++) {

      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];

      if (att->Renderbuffer) {

         _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);

      }

      if (att->Texture) {

         _mesa_reference_texobj(&att->Texture, NULL);

      }

      assert(!att->Renderbuffer);

      assert(!att->Texture);

      att->Type = GL_NONE;

   }

}

/**

 * Set *ptr to point to fb, with refcounting and locking.

 * This is normally only called from the _mesa_reference_framebuffer() macro

 * when there's a real pointer change.

 */

void

_mesa_reference_framebuffer_(struct gl_framebuffer **ptr,

                             struct gl_framebuffer *fb)

{

   if (*ptr) {

      /* unreference old renderbuffer */

      GLboolean deleteFlag = GL_FALSE;

      struct gl_framebuffer *oldFb = *ptr;

      mtx_lock(&oldFb->Mutex);

      assert(oldFb->RefCount > 0);

      oldFb->RefCount--;

      deleteFlag = (oldFb->RefCount == 0);

      mtx_unlock(&oldFb->Mutex);

      if (deleteFlag)

         oldFb->Delete(oldFb);

      *ptr = NULL;

   }

   assert(!*ptr);

   if (fb) {

      mtx_lock(&fb->Mutex);

      fb->RefCount++;

      mtx_unlock(&fb->Mutex);

      *ptr = fb;

   }

}

/**

 * Resize the given framebuffer's renderbuffers to the new width and height.

 * This should only be used for window-system framebuffers, not

 * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).

 * This will typically be called via ctx->Driver.ResizeBuffers() or directly

 * from a device driver.

 *

 * \note it's possible for ctx to be null since a window can be resized

 * without a currently bound rendering context.

 */

void

_mesa_resize_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb,

                         GLuint width, GLuint height)

{

   GLuint i;

   /* XXX I think we could check if the size is not changing

    * and return early.

    */

   /* Can only resize win-sys framebuffer objects */

   assert(_mesa_is_winsys_fbo(fb));

   for (i = 0; i < BUFFER_COUNT; i++) {

      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];

      if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {

         struct gl_renderbuffer *rb = att->Renderbuffer;

         /* only resize if size is changing */

         if (rb->Width != width || rb->Height != height) {

            if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {

               assert(rb->Width == width);

               assert(rb->Height == height);

            }

            else {

               _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");

               /* no return */

            }

         }

      }

   }

   fb->Width = width;

   fb->Height = height;

   if (ctx) {

      /* update scissor / window bounds */

      _mesa_update_draw_buffer_bounds(ctx, ctx->DrawBuffer);

      /* Signal new buffer state so that swrast will update its clipping

       * info (the CLIP_BIT flag).

       */

      ctx->NewState |= _NEW_BUFFERS;

   }

}

/**

 * Examine all the framebuffer's renderbuffers to update the Width/Height

 * fields of the framebuffer.  If we have renderbuffers with different

 * sizes, set the framebuffer's width and height to the min size.

 * Note: this is only intended for user-created framebuffers, not

 * window-system framebuffes.

 */

static void

update_framebuffer_size(struct gl_context *ctx, struct gl_framebuffer *fb)

{

   GLuint minWidth = ~0, minHeight = ~0;

   GLuint i;

   /* user-created framebuffers only */

   assert(_mesa_is_user_fbo(fb));

   for (i = 0; i < BUFFER_COUNT; i++) {

      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];

      const struct gl_renderbuffer *rb = att->Renderbuffer;

      if (rb) {

         minWidth = MIN2(minWidth, rb->Width);

         minHeight = MIN2(minHeight, rb->Height);

      }

   }

   if (minWidth != ~0U) {

      fb->Width = minWidth;

      fb->Height = minHeight;

   }

   else {

      fb->Width = 0;

      fb->Height = 0;

   }

}

/**

 * Calculate the inclusive bounding box for the scissor of a specific viewport

 *

 * \param ctx     GL context.

 * \param buffer  Framebuffer to be checked against

 * \param idx     Index of the desired viewport

 * \param bbox    Bounding box for the scissored viewport.  Stored as xmin,

 *                xmax, ymin, ymax.

 *

 * \warning This function assumes that the framebuffer dimensions are up to

 * date (e.g., update_framebuffer_size has been recently called on \c buffer).

 *

 * \sa _mesa_clip_to_region

 */

void

_mesa_scissor_bounding_box(const struct gl_context *ctx,

                           const struct gl_framebuffer *buffer,

                           unsigned idx, int *bbox)

{

   bbox[0] = 0;

   bbox[2] = 0;

   bbox[1] = buffer->Width;

   bbox[3] = buffer->Height;

   if (ctx->Scissor.EnableFlags & (1u << idx)) {

      if (ctx->Scissor.ScissorArray[idx].X > bbox[0]) {

         bbox[0] = ctx->Scissor.ScissorArray[idx].X;

      }

      if (ctx->Scissor.ScissorArray[idx].Y > bbox[2]) {

         bbox[2] = ctx->Scissor.ScissorArray[idx].Y;

      }

      if (ctx->Scissor.ScissorArray[idx].X + ctx->Scissor.ScissorArray[idx].Width < bbox[1]) {

         bbox[1] = ctx->Scissor.ScissorArray[idx].X + ctx->Scissor.ScissorArray[idx].Width;

      }

      if (ctx->Scissor.ScissorArray[idx].Y + ctx->Scissor.ScissorArray[idx].Height < bbox[3]) {

         bbox[3] = ctx->Scissor.ScissorArray[idx].Y + ctx->Scissor.ScissorArray[idx].Height;

      }

      /* finally, check for empty region */

      if (bbox[0] > bbox[1]) {

         bbox[0] = bbox[1];

      }

      if (bbox[2] > bbox[3]) {

         bbox[2] = bbox[3];

      }

   }

   assert(bbox[0] <= bbox[1]);

   assert(bbox[2] <= bbox[3]);

}

/**

 * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.

 * These values are computed from the buffer's width and height and

 * the scissor box, if it's enabled.

 * \param ctx  the GL context.

 */

void

_mesa_update_draw_buffer_bounds(struct gl_context *ctx,

                                struct gl_framebuffer *buffer)

{

   int bbox[4];

   if (!buffer)

      return;

   if (_mesa_is_user_fbo(buffer)) {

      /* user-created framebuffer size depends on the renderbuffers */

      update_framebuffer_size(ctx, buffer);

   }

   /* Default to the first scissor as that's always valid */

   _mesa_scissor_bounding_box(ctx, buffer, 0, bbox);

   buffer->_Xmin = bbox[0];

   buffer->_Ymin = bbox[2];

   buffer->_Xmax = bbox[1];

   buffer->_Ymax = bbox[3];

}

/**

 * The glGet queries of the framebuffer red/green/blue size, stencil size,

 * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can

 * change depending on the renderbuffer bindings.  This function updates

 * the given framebuffer's Visual from the current renderbuffer bindings.

 *

 * This may apply to user-created framebuffers or window system framebuffers.

 *

 * Also note: ctx->DrawBuffer->Visual.depthBits might not equal

 * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.

 * The former one is used to convert floating point depth values into

 * integer Z values.

 */

void

_mesa_update_framebuffer_visual(struct gl_context *ctx,

				struct gl_framebuffer *fb)

{

   GLuint i;

   memset(&fb->Visual, 0, sizeof(fb->Visual));

   fb->Visual.rgbMode = GL_TRUE; /* assume this */

#if 0 /* this _might_ be needed */

   if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {

      /* leave visual fields zero'd */

      return;

   }

#endif

   /* find first RGB renderbuffer */

   for (i = 0; i < BUFFER_COUNT; i++) {

      if (fb->Attachment[i].Renderbuffer) {

         const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;

         const GLenum baseFormat = _mesa_get_format_base_format(rb->Format);

         const mesa_format fmt = rb->Format;

         /* Grab samples and sampleBuffers from any attachment point (assuming

          * the framebuffer is complete, we'll get the same answer from all

          * attachments).

          */

         fb->Visual.samples = rb->NumSamples;

         fb->Visual.sampleBuffers = rb->NumSamples > 0 ? 1 : 0;

         if (_mesa_is_legal_color_format(ctx, baseFormat)) {

            fb->Visual.redBits = _mesa_get_format_bits(fmt, GL_RED_BITS);

            fb->Visual.greenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);

            fb->Visual.blueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);

            fb->Visual.alphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);

            fb->Visual.rgbBits = fb->Visual.redBits

               + fb->Visual.greenBits + fb->Visual.blueBits;

            if (_mesa_get_format_color_encoding(fmt) == GL_SRGB)

                fb->Visual.sRGBCapable = ctx->Extensions.EXT_framebuffer_sRGB;

            break;

         }

      }

   }

   fb->Visual.floatMode = GL_FALSE;

   for (i = 0; i < BUFFER_COUNT; i++) {

      if (fb->Attachment[i].Renderbuffer) {

         const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;

         const mesa_format fmt = rb->Format;

         if (_mesa_get_format_datatype(fmt) == GL_FLOAT) {

            fb->Visual.floatMode = GL_TRUE;

            break;

         }

      }

   }

   if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {

      const struct gl_renderbuffer *rb =

         fb->Attachment[BUFFER_DEPTH].Renderbuffer;

      const mesa_format fmt = rb->Format;

      fb->Visual.haveDepthBuffer = GL_TRUE;

      fb->Visual.depthBits = _mesa_get_format_bits(fmt, GL_DEPTH_BITS);

   }

   if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {

      const struct gl_renderbuffer *rb =

         fb->Attachment[BUFFER_STENCIL].Renderbuffer;

      const mesa_format fmt = rb->Format;

      fb->Visual.haveStencilBuffer = GL_TRUE;

      fb->Visual.stencilBits = _mesa_get_format_bits(fmt, GL_STENCIL_BITS);

   }

   if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {

      const struct gl_renderbuffer *rb =

         fb->Attachment[BUFFER_ACCUM].Renderbuffer;

      const mesa_format fmt = rb->Format;

      fb->Visual.haveAccumBuffer = GL_TRUE;

      fb->Visual.accumRedBits = _mesa_get_format_bits(fmt, GL_RED_BITS);

      fb->Visual.accumGreenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);

      fb->Visual.accumBlueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);

      fb->Visual.accumAlphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);

   }

   compute_depth_max(fb);

}

/*

 * Example DrawBuffers scenarios:

 *

 * 1. glDrawBuffer(GL_FRONT_AND_BACK), fixed-func or shader writes to

 * "gl_FragColor" or program writes to the "result.color" register:

 *

 *   fragment color output   renderbuffer

 *   ---------------------   ---------------

 *   color[0]                Front, Back

 *

 *

 * 2. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]), shader writes to

 * gl_FragData[i] or program writes to result.color[i] registers:

 *

 *   fragment color output   renderbuffer

 *   ---------------------   ---------------

 *   color[0]                Front

 *   color[1]                Aux0

 *   color[3]                Aux1

 *

 *

 * 3. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]) and shader writes to

 * gl_FragColor, or fixed function:

 *

 *   fragment color output   renderbuffer

 *   ---------------------   ---------------

 *   color[0]                Front, Aux0, Aux1

 *

 *

 * In either case, the list of renderbuffers is stored in the

 * framebuffer->_ColorDrawBuffers[] array and

 * framebuffer->_NumColorDrawBuffers indicates the number of buffers.

 * The renderer (like swrast) has to look at the current fragment shader

 * to see if it writes to gl_FragColor vs. gl_FragData[i] to determine

 * how to map color outputs to renderbuffers.

 *

 * Note that these two calls are equivalent (for fixed function fragment

 * shading anyway):

 *   a)  glDrawBuffer(GL_FRONT_AND_BACK);  (assuming non-stereo framebuffer)

 *   b)  glDrawBuffers(2, [GL_FRONT_LEFT, GL_BACK_LEFT]);

 */

/**

 * Update the (derived) list of color drawing renderbuffer pointers.

 * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers

 * writing colors.

 */

static void

update_color_draw_buffers(struct gl_context *ctx, struct gl_framebuffer *fb)

{

   GLuint output;

   /* set 0th buffer to NULL now in case _NumColorDrawBuffers is zero */

   fb->_ColorDrawBuffers[0] = NULL;

   for (output = 0; output < fb->_NumColorDrawBuffers; output++) {

      GLint buf = fb->_ColorDrawBufferIndexes[output];

      if (buf >= 0) {

         fb->_ColorDrawBuffers[output] = fb->Attachment[buf].Renderbuffer;

      }

      else {

         fb->_ColorDrawBuffers[output] = NULL;

      }

   }

}

/**

 * Update the (derived) color read renderbuffer pointer.

 * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.

 */

static void

update_color_read_buffer(struct gl_context *ctx, struct gl_framebuffer *fb)

{

   (void) ctx;

   if (fb->_ColorReadBufferIndex == -1 ||

       fb->DeletePending ||

       fb->Width == 0 ||

       fb->Height == 0) {

      fb->_ColorReadBuffer = NULL; /* legal! */

   }

   else {

      assert(fb->_ColorReadBufferIndex >= 0);

      assert(fb->_ColorReadBufferIndex < BUFFER_COUNT);

      fb->_ColorReadBuffer

         = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;

   }

}

/**

 * Update a gl_framebuffer's derived state.

 *

 * Specifically, update these framebuffer fields:

 *    _ColorDrawBuffers

 *    _NumColorDrawBuffers

 *    _ColorReadBuffer

 *

 * If the framebuffer is user-created, make sure it's complete.

 *

 * The following functions (at least) can effect framebuffer state:

 * glReadBuffer, glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,

 * glRenderbufferStorageEXT.

 */

static void

update_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)

{

   if (_mesa_is_winsys_fbo(fb)) {

      /* This is a window-system framebuffer */

      /* Need to update the FB's GL_DRAW_BUFFER state to match the

       * context state (GL_READ_BUFFER too).

       */

      if (fb->ColorDrawBuffer[0] != ctx->Color.DrawBuffer[0]) {

         _mesa_drawbuffers(ctx, fb, ctx->Const.MaxDrawBuffers,

                           ctx->Color.DrawBuffer, NULL);

      }

   }

   else {

      /* This is a user-created framebuffer.

       * Completeness only matters for user-created framebuffers.

       */

      if (fb->_Status != GL_FRAMEBUFFER_COMPLETE) {

         _mesa_test_framebuffer_completeness(ctx, fb);

      }

   }

   /* Strictly speaking, we don't need to update the draw-state

    * if this FB is bound as ctx->ReadBuffer (and conversely, the

    * read-state if this FB is bound as ctx->DrawBuffer), but no

    * harm.

    */

   update_color_draw_buffers(ctx, fb);

   update_color_read_buffer(ctx, fb);

   compute_depth_max(fb);

}

/**

 * Update state related to the draw/read framebuffers.

 */

void

_mesa_update_framebuffer(struct gl_context *ctx,

                         struct gl_framebuffer *readFb,

                         struct gl_framebuffer *drawFb)

{

   assert(ctx);

   update_framebuffer(ctx, drawFb);

   if (readFb != drawFb)

      update_framebuffer(ctx, readFb);

   _mesa_update_clamp_vertex_color(ctx, drawFb);

   _mesa_update_clamp_fragment_color(ctx, drawFb);

}

/**

 * Check if the renderbuffer for a read/draw operation exists.

 * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,

 *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.

 * \param reading  if TRUE, we're going to read from the buffer,

                   if FALSE, we're going to write to the buffer.

 * \return GL_TRUE if buffer exists, GL_FALSE otherwise

 */

static GLboolean

renderbuffer_exists(struct gl_context *ctx,

                    struct gl_framebuffer *fb,

                    GLenum format,

                    GLboolean reading)

{

   const struct gl_renderbuffer_attachment *att = fb->Attachment;

   /* If we don't know the framebuffer status, update it now */

   if (fb->_Status == 0) {

      _mesa_test_framebuffer_completeness(ctx, fb);

   }

   if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {

      return GL_FALSE;

   }

   switch (format) {

   case GL_COLOR:

   case GL_RED:

   case GL_GREEN:

   case GL_BLUE:

   case GL_ALPHA:

   case GL_LUMINANCE:

   case GL_LUMINANCE_ALPHA:

   case GL_INTENSITY:

   case GL_RG:

   case GL_RGB:

   case GL_BGR:

   case GL_RGBA:

   case GL_BGRA:

   case GL_ABGR_EXT:

   case GL_RED_INTEGER_EXT:

   case GL_RG_INTEGER:

   case GL_GREEN_INTEGER_EXT:

   case GL_BLUE_INTEGER_EXT:

   case GL_ALPHA_INTEGER_EXT:

   case GL_RGB_INTEGER_EXT:

   case GL_RGBA_INTEGER_EXT:

   case GL_BGR_INTEGER_EXT:

   case GL_BGRA_INTEGER_EXT:

   case GL_LUMINANCE_INTEGER_EXT:

   case GL_LUMINANCE_ALPHA_INTEGER_EXT:

      if (reading) {

         /* about to read from a color buffer */

         const struct gl_renderbuffer *readBuf = fb->_ColorReadBuffer;

         if (!readBuf) {

            return GL_FALSE;

         }

         assert(_mesa_get_format_bits(readBuf->Format, GL_RED_BITS) > 0 ||

                _mesa_get_format_bits(readBuf->Format, GL_ALPHA_BITS) > 0 ||

                _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_LUMINANCE_SIZE) > 0 ||

                _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_INTENSITY_SIZE) > 0 ||

                _mesa_get_format_bits(readBuf->Format, GL_INDEX_BITS) > 0);

      }

      else {

         /* about to draw to zero or more color buffers (none is OK) */

         return GL_TRUE;

      }

      break;

   case GL_DEPTH:

   case GL_DEPTH_COMPONENT:

      if (att[BUFFER_DEPTH].Type == GL_NONE) {

         return GL_FALSE;

      }

      break;

   case GL_STENCIL:

   case GL_STENCIL_INDEX:

      if (att[BUFFER_STENCIL].Type == GL_NONE) {

         return GL_FALSE;

      }

      break;

   case GL_DEPTH_STENCIL_EXT:

      if (att[BUFFER_DEPTH].Type == GL_NONE ||

          att[BUFFER_STENCIL].Type == GL_NONE) {

         return GL_FALSE;

      }

      break;

   default:

      _mesa_problem(ctx,

                    "Unexpected format 0x%x in renderbuffer_exists",

                    format);

      return GL_FALSE;

   }

   /* OK */

   return GL_TRUE;

}

/**

 * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,

 * glCopyTex[Sub]Image, etc) exists.

 * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,

 *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.

 * \return GL_TRUE if buffer exists, GL_FALSE otherwise

 */

GLboolean

_mesa_source_buffer_exists(struct gl_context *ctx, GLenum format)

{

   return renderbuffer_exists(ctx, ctx->ReadBuffer, format, GL_TRUE);

}

/**

 * As above, but for drawing operations.

 */

GLboolean

_mesa_dest_buffer_exists(struct gl_context *ctx, GLenum format)

{

   return renderbuffer_exists(ctx, ctx->DrawBuffer, format, GL_FALSE);

}

/**

 * Used to answer the GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES query.

 */

GLenum

_mesa_get_color_read_format(struct gl_context *ctx)

{

   if (!ctx->ReadBuffer || !ctx->ReadBuffer->_ColorReadBuffer) {

      /* The spec is unclear how to handle this case, but NVIDIA's

       * driver generates GL_INVALID_OPERATION.

       */

      _mesa_error(ctx, GL_INVALID_OPERATION,

                  "glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT: "

                  "no GL_READ_BUFFER)");

      return GL_NONE;

   }

   else {

      const GLenum format = ctx->ReadBuffer->_ColorReadBuffer->Format;

      const GLenum data_type = _mesa_get_format_datatype(format);

      if (format == MESA_FORMAT_B8G8R8A8_UNORM)

         return GL_BGRA;

      else if (format == MESA_FORMAT_B5G6R5_UNORM)

         return GL_BGR;

      switch (data_type) {

      case GL_UNSIGNED_INT:

      case GL_INT:

         return GL_RGBA_INTEGER;

      default:

         return GL_RGBA;

      }

   }

}

/**

 * Used to answer the GL_IMPLEMENTATION_COLOR_READ_TYPE_OES query.

 */

GLenum

_mesa_get_color_read_type(struct gl_context *ctx)

{

   if (!ctx->ReadBuffer || !ctx->ReadBuffer->_ColorReadBuffer) {

      /* The spec is unclear how to handle this case, but NVIDIA's

       * driver generates GL_INVALID_OPERATION.

       */

      _mesa_error(ctx, GL_INVALID_OPERATION,

                  "glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE: "

                  "no GL_READ_BUFFER)");

      return GL_NONE;

   }

   else {

      const GLenum format = ctx->ReadBuffer->_ColorReadBuffer->Format;

      const GLenum data_type = _mesa_get_format_datatype(format);

      if (format == MESA_FORMAT_B5G6R5_UNORM)

         return GL_UNSIGNED_SHORT_5_6_5_REV;

      switch (data_type) {

      case GL_SIGNED_NORMALIZED:

         return GL_BYTE;

      case GL_UNSIGNED_INT:

      case GL_INT:

      case GL_FLOAT:

         return data_type;

      case GL_UNSIGNED_NORMALIZED:

      default:

         return GL_UNSIGNED_BYTE;

      }

   }

}

/**

 * Returns the read renderbuffer for the specified format.

 */

struct gl_renderbuffer *

_mesa_get_read_renderbuffer_for_format(const struct gl_context *ctx,

                                       GLenum format)

{

   const struct gl_framebuffer *rfb = ctx->ReadBuffer;

   if (_mesa_is_color_format(format)) {

      return rfb->Attachment[rfb->_ColorReadBufferIndex].Renderbuffer;

   } else if (_mesa_is_depth_format(format) ||

              _mesa_is_depthstencil_format(format)) {

      return rfb->Attachment[BUFFER_DEPTH].Renderbuffer;

   } else {

      return rfb->Attachment[BUFFER_STENCIL].Renderbuffer;

   }

}

/**

 * Print framebuffer info to stderr, for debugging.

 */

void

_mesa_print_framebuffer(const struct gl_framebuffer *fb)

{

   GLuint i;

   fprintf(stderr, "Mesa Framebuffer %u at %p\n", fb->Name, (void *) fb);

   fprintf(stderr, "  Size: %u x %u  Status: %s\n", fb->Width, fb->Height,

           _mesa_lookup_enum_by_nr(fb->_Status));

   fprintf(stderr, "  Attachments:\n");

   for (i = 0; i < BUFFER_COUNT; i++) {

      const struct gl_renderbuffer_attachment *att = &fb->Attachment[i];

      if (att->Type == GL_TEXTURE) {

         const struct gl_texture_image *texImage = att->Renderbuffer->TexImage;

         fprintf(stderr,

                 "  %2d: Texture %u, level %u, face %u, slice %u, complete %d\n",

                 i, att->Texture->Name, att->TextureLevel, att->CubeMapFace,

                 att->Zoffset, att->Complete);

         fprintf(stderr, "       Size: %u x %u x %u  Format %s\n",

                 texImage->Width, texImage->Height, texImage->Depth,

                 _mesa_get_format_name(texImage->TexFormat));

      }

      else if (att->Type == GL_RENDERBUFFER) {

         fprintf(stderr, "  %2d: Renderbuffer %u, complete %d\n",

                 i, att->Renderbuffer->Name, att->Complete);

         fprintf(stderr, "       Size: %u x %u  Format %s\n",

                 att->Renderbuffer->Width, att->Renderbuffer->Height,

                 _mesa_get_format_name(att->Renderbuffer->Format));

      }

      else {

         fprintf(stderr, "  %2d: none\n", i);

      }

   }

}