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 /*

  * Copyright 2011 Google Inc.

  *

  * Use of this source code is governed by a BSD-style license that can be

  * found in the LICENSE file.

  */

 #ifndef GrGLConfig_DEFINED

 #define GrGLConfig_DEFINED

 #include "GrTypes.h"

 /**

  * Optional GL config file.

  */

 #ifdef GR_GL_CUSTOM_SETUP_HEADER

     #include GR_GL_CUSTOM_SETUP_HEADER

 #endif

 #if !defined(GR_GL_FUNCTION_TYPE)

     #define GR_GL_FUNCTION_TYPE

 #endif

 /**

  * The following are optional defines that can be enabled at the compiler

  * command line, in a IDE project, in a GrUserConfig.h file, or in a GL custom

  * file (if one is in use). If a GR_GL_CUSTOM_SETUP_HEADER is used they can

  * also be placed there.

  *

  * GR_GL_LOG_CALLS: if 1 Gr can print every GL call using GrPrintf. Defaults to

  * 0. Logging can be enabled and disabled at runtime using a debugger via to

  * global gLogCallsGL. The initial value of gLogCallsGL is controlled by

  * GR_GL_LOG_CALLS_START.

  *

  * GR_GL_LOG_CALLS_START: controls the initial value of gLogCallsGL when

  * GR_GL_LOG_CALLS is 1. Defaults to 0.

  *

  * GR_GL_CHECK_ERROR: if enabled Gr can do a glGetError() after every GL call.

  * Defaults to 1 if SK_DEBUG is set, otherwise 0. When GR_GL_CHECK_ERROR is 1

  * this can be toggled in a debugger using the gCheckErrorGL global. The initial

  * value of gCheckErrorGL is controlled by by GR_GL_CHECK_ERROR_START.

  *

  * GR_GL_CHECK_ERROR_START: controls the initial value of gCheckErrorGL

  * when GR_GL_CHECK_ERROR is 1.  Defaults to 1.

  *

  * GR_GL_NO_CONSTANT_ATTRIBUTES: if this evaluates to true then the GL backend

  * will use uniforms instead of attributes in all cases when there is not

  * per-vertex data. This is important when the underlying GL implementation

  * doesn't actually support immediate style attribute values (e.g. when

  * the GL stream is converted to DX as in ANGLE on Chrome). Defaults to 0.

  *

  * GR_GL_USE_BUFFER_DATA_NULL_HINT: When specifing new data for a vertex/index

  * buffer that replaces old data Ganesh can give a hint to the driver that the

  * previous data will not be used in future draws like this:

  *  glBufferData(GL_..._BUFFER, size, NULL, usage);       //<--hint, NULL means

  *  glBufferSubData(GL_..._BUFFER, 0, lessThanSize, data) //   old data can't be

  *                                                        //   used again.

  * However, this can be an unoptimization on some platforms, esp. Chrome.

  * Chrome's cmd buffer will create a new allocation and memset the whole thing

  * to zero (for security reasons). Defaults to 1 (enabled).

  *

  * GR_GL_PER_GL_FUNC_CALLBACK: When set to 1 the GrGLInterface object provides

  * a function pointer that is called just before every gl function. The ptr must

  * be valid (i.e. there is no NULL check). However, by default the callback will

  * be set to a function that does nothing. The signature of the function is:

  *    void function(const GrGLInterface*)

  * It is not extern "C".

  * The GrGLInterface field fCallback specifies the function ptr and there is an

  * additional field fCallbackData of type intptr_t for client data.

  *

  * GR_GL_RGBA_8888_PIXEL_OPS_SLOW: Set this to 1 if it is known that performing

  * glReadPixels / glTex(Sub)Image with format=GL_RGBA, type=GL_UNISIGNED_BYTE is

  * significantly slower than format=GL_BGRA, type=GL_UNISIGNED_BYTE.

  *

  * GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL: Set this to 1 if calling

  * glReadPixels to read the entire framebuffer is faster than calling it with

  * the same sized rectangle but with a framebuffer bound that is larger than

  * the rectangle read.

  *

  * GR_GL_CHECK_ALLOC_WITH_GET_ERROR: If set to 1 this will then glTexImage,

  * glBufferData, glRenderbufferStorage, etc will be checked for errors. This

  * amounts to ensuring the error is GL_NO_ERROR, calling the allocating

  * function, and then checking that the error is still GL_NO_ERROR. When the

  * value is 0 we will assume no error was generated without checking.

  *

  * GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT: We will normally check the FBO status

  * every time we bind a texture or renderbuffer to an FBO. However, in some

  * environments CheckFrameBufferStatus is very expensive. If this is set we will

  * check the first time we use a color format or a combination of color /

  * stencil formats as attachments. If the FBO is complete we will assume

  * subsequent attachments with the same formats are complete as well.

  *

  * GR_GL_MUST_USE_VBO: Indicates that all vertices and indices must be rendered

  * from VBOs. Chromium's command buffer doesn't allow glVertexAttribArray with

  * ARARY_BUFFER 0 bound or glDrawElements with ELEMENT_ARRAY_BUFFER 0 bound.

  *

  * GR_GL_USE_NEW_SHADER_SOURCE_SIGNATURE is for compatibility with the new version

  * of the OpenGLES2.0 headers from Khronos.  glShaderSource now takes a const char * const *,

  * instead of a const char

  */

 #if !defined(GR_GL_LOG_CALLS)

     #ifdef SK_DEBUG

         #define GR_GL_LOG_CALLS 1

     #else

         #define GR_GL_LOG_CALLS 0

     #endif

 #endif

 #if !defined(GR_GL_LOG_CALLS_START)

     #define GR_GL_LOG_CALLS_START                       0

 #endif

 #if !defined(GR_GL_CHECK_ERROR)

     #ifdef SK_DEBUG

         #define GR_GL_CHECK_ERROR 1

     #else

         #define GR_GL_CHECK_ERROR 0

     #endif

 #endif

 #if !defined(GR_GL_CHECK_ERROR_START)

     #define GR_GL_CHECK_ERROR_START                     1

 #endif

 #if !defined(GR_GL_NO_CONSTANT_ATTRIBUTES)

     #define GR_GL_NO_CONSTANT_ATTRIBUTES                0

 #endif

 #if !defined(GR_GL_USE_BUFFER_DATA_NULL_HINT)

     #define GR_GL_USE_BUFFER_DATA_NULL_HINT             1

 #endif

 #if !defined(GR_GL_PER_GL_FUNC_CALLBACK)

     #define GR_GL_PER_GL_FUNC_CALLBACK                  0

 #endif

 #if !defined(GR_GL_RGBA_8888_PIXEL_OPS_SLOW)

     #define GR_GL_RGBA_8888_PIXEL_OPS_SLOW              0

 #endif

 #if !defined(GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL)

     #define GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL   0

 #endif

 #if !defined(GR_GL_CHECK_ALLOC_WITH_GET_ERROR)

     #define GR_GL_CHECK_ALLOC_WITH_GET_ERROR            1

 #endif

 #if !defined(GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT)

     #define GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT      0

 #endif

 #if !defined(GR_GL_MUST_USE_VBO)

     #define GR_GL_MUST_USE_VBO                          0

 #endif

 #if !defined(GR_GL_USE_NEW_SHADER_SOURCE_SIGNATURE)

     #define GR_GL_USE_NEW_SHADER_SOURCE_SIGNATURE       0

 #endif

 /**

  * There is a strange bug that occurs on Macs with NVIDIA GPUs. We don't

  * fully understand it. When (element) array buffers are continually

  * respecified using glBufferData performance can fall off of a cliff. The

  * driver winds up performing many DMA mapping / unmappings and chews up ~50% of

  * the core. However, it has been observed that occaisonally respecifiying the

  * buffer using glBufferData and then writing data using glBufferSubData

  * prevents the bad behavior.

  *

  * There is a lot of uncertainty around this issue. In Chrome backgrounding

  * the tab somehow initiates this behavior and we don't know what the connection

  * is. Another observation is that Chrome's cmd buffer server will actually

  * create a buffer full of zeros when it sees a NULL data param (for security

  * reasons). If this is disabled and NULL is actually passed all the way to the

  * driver then the workaround doesn't help.

  *

  * The issue is tracked at:

  * http://code.google.com/p/chromium/issues/detail?id=114865

  *

  * When the workaround is enabled we will use the glBufferData / glBufferSubData

  * trick every 128 array buffer uploads.

  *

  * Hopefully we will understand this better and have a cleaner fix or get a

  * OS/driver level fix.

  */

 #define GR_GL_MAC_BUFFER_OBJECT_PERFOMANCE_WORKAROUND   \

     (defined(SK_BUILD_FOR_MAC) &&                       \

      !GR_GL_USE_BUFFER_DATA_NULL_HINT)

 #endif