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      1 
      2 /*
      3  * Copyright 2011 Google Inc.
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 
     10 
     11 #ifndef GrGLConfig_DEFINED
     12 #define GrGLConfig_DEFINED
     13 
     14 #include "GrTypes.h"
     15 
     16 /**
     17  * Optional GL config file.
     18  */
     19 #ifdef GR_GL_CUSTOM_SETUP_HEADER
     20     #include GR_GL_CUSTOM_SETUP_HEADER
     21 #endif
     22 
     23 #if !defined(GR_GL_FUNCTION_TYPE)
     24     #define GR_GL_FUNCTION_TYPE
     25 #endif
     26 
     27 /**
     28  * The following are optional defines that can be enabled at the compiler
     29  * command line, in a IDE project, in a GrUserConfig.h file, or in a GL custom
     30  * file (if one is in use). If a GR_GL_CUSTOM_SETUP_HEADER is used they can
     31  * also be placed there.
     32  *
     33  * GR_GL_LOG_CALLS: if 1 Gr can print every GL call using GrPrintf. Defaults to
     34  * 0. Logging can be enabled and disabled at runtime using a debugger via to
     35  * global gLogCallsGL. The initial value of gLogCallsGL is controlled by
     36  * GR_GL_LOG_CALLS_START.
     37  *
     38  * GR_GL_LOG_CALLS_START: controls the initial value of gLogCallsGL when
     39  * GR_GL_LOG_CALLS is 1. Defaults to 0.
     40  *
     41  * GR_GL_CHECK_ERROR: if enabled Gr can do a glGetError() after every GL call.
     42  * Defaults to 1 if GR_DEBUG is set, otherwise 0. When GR_GL_CHECK_ERROR is 1
     43  * this can be toggled in a debugger using the gCheckErrorGL global. The initial
     44  * value of gCheckErrorGL is controlled by by GR_GL_CHECK_ERROR_START.
     45  *
     46  * GR_GL_CHECK_ERROR_START: controls the initial value of gCheckErrorGL
     47  * when GR_GL_CHECK_ERROR is 1.  Defaults to 1.
     48  *
     49  * GR_GL_NO_CONSTANT_ATTRIBUTES: if this evaluates to true then the GL backend
     50  * will use uniforms instead of attributes in all cases when there is not
     51  * per-vertex data. This is important when the underlying GL implementation
     52  * doesn't actually support immediate style attribute values (e.g. when
     53  * the GL stream is converted to DX as in ANGLE on Chrome). Defaults to 0.
     54  *
     55  * GR_GL_USE_BUFFER_DATA_NULL_HINT: When specifing new data for a vertex/index
     56  * buffer that replaces old data Ganesh can give a hint to the driver that the
     57  * previous data will not be used in future draws like this:
     58  *  glBufferData(GL_..._BUFFER, size, NULL, usage);       //<--hint, NULL means
     59  *  glBufferSubData(GL_..._BUFFER, 0, lessThanSize, data) //   old data can't be
     60  *                                                        //   used again.
     61  * However, this can be an unoptimization on some platforms, esp. Chrome.
     62  * Chrome's cmd buffer will create a new allocation and memset the whole thing
     63  * to zero (for security reasons). Defaults to 1 (enabled).
     64  *
     65  * GR_GL_PER_GL_FUNC_CALLBACK: When set to 1 the GrGLInterface object provides
     66  * a function pointer that is called just before every gl function. The ptr must
     67  * be valid (i.e. there is no NULL check). However, by default the callback will
     68  * be set to a function that does nothing. The signature of the function is:
     69  *    void function(const GrGLInterface*)
     70  * It is not extern "C".
     71  * The GrGLInterface field fCallback specifies the function ptr and there is an
     72  * additional field fCallbackData of type intptr_t for client data.
     73  *
     74  * GR_GL_RGBA_8888_PIXEL_OPS_SLOW: Set this to 1 if it is known that performing
     75  * glReadPixels / glTex(Sub)Image with format=GL_RGBA, type=GL_UNISIGNED_BYTE is
     76  * significantly slower than format=GL_BGRA, type=GL_UNISIGNED_BYTE.
     77  *
     78  * GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL: Set this to 1 if calling
     79  * glReadPixels to read the entire framebuffer is faster than calling it with
     80  * the same sized rectangle but with a framebuffer bound that is larger than
     81  * the rectangle read.
     82  *
     83  * GR_GL_CHECK_ALLOC_WITH_GET_ERROR: If set to 1 this will then glTexImage,
     84  * glBufferData, glRenderbufferStorage, etc will be checked for errors. This
     85  * amounts to ensuring the error is GL_NO_ERROR, calling the allocating
     86  * function, and then checking that the error is still GL_NO_ERROR. When the
     87  * value is 0 we will assume no error was generated without checking.
     88  *
     89  * GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT: We will normally check the FBO status
     90  * every time we bind a texture or renderbuffer to an FBO. However, in some
     91  * environments CheckFrameBufferStatus is very expensive. If this is set we will
     92  * check the first time we use a color format or a combination of color /
     93  * stencil formats as attachments. If the FBO is complete we will assume
     94  * subsequent attachments with the same formats are complete as well.
     95  *
     96  * GR_GL_USE_NV_PATH_RENDERING: Enable experimental support for
     97  * GL_NV_path_rendering. There are known issues with clipping, non-AA paths, and
     98  * perspective.
     99  */
    100 
    101 #if !defined(GR_GL_LOG_CALLS)
    102     #define GR_GL_LOG_CALLS                             GR_DEBUG
    103 #endif
    104 
    105 #if !defined(GR_GL_LOG_CALLS_START)
    106     #define GR_GL_LOG_CALLS_START                       0
    107 #endif
    108 
    109 #if !defined(GR_GL_CHECK_ERROR)
    110     #define GR_GL_CHECK_ERROR                           GR_DEBUG
    111 #endif
    112 
    113 #if !defined(GR_GL_CHECK_ERROR_START)
    114     #define GR_GL_CHECK_ERROR_START                     1
    115 #endif
    116 
    117 #if !defined(GR_GL_NO_CONSTANT_ATTRIBUTES)
    118     #define GR_GL_NO_CONSTANT_ATTRIBUTES                0
    119 #endif
    120 
    121 #if !defined(GR_GL_USE_BUFFER_DATA_NULL_HINT)
    122     #define GR_GL_USE_BUFFER_DATA_NULL_HINT             1
    123 #endif
    124 
    125 #if !defined(GR_GL_PER_GL_FUNC_CALLBACK)
    126     #define GR_GL_PER_GL_FUNC_CALLBACK                  0
    127 #endif
    128 
    129 #if !defined(GR_GL_RGBA_8888_PIXEL_OPS_SLOW)
    130     #define GR_GL_RGBA_8888_PIXEL_OPS_SLOW              0
    131 #endif
    132 
    133 #if !defined(GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL)
    134     #define GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL   0
    135 #endif
    136 
    137 #if !defined(GR_GL_CHECK_ALLOC_WITH_GET_ERROR)
    138     #define GR_GL_CHECK_ALLOC_WITH_GET_ERROR            1
    139 #endif
    140 
    141 #if !defined(GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT)
    142     #define GR_GL_CHECK_FBO_STATUS_ONCE_PER_FORMAT      0
    143 #endif
    144 
    145 #if !defined(GR_GL_USE_NV_PATH_RENDERING)
    146     #define GR_GL_USE_NV_PATH_RENDERING                 0
    147 #endif
    148 
    149 /**
    150  * There is a strange bug that occurs on Macs with NVIDIA GPUs. We don't
    151  * fully understand it. When (element) array buffers are continually
    152  * respecified using glBufferData performance can fall off of a cliff. The
    153  * driver winds up performing many DMA mapping / unmappings and chews up ~50% of
    154  * the core. However, it has been observed that occaisonally respecifiying the
    155  * buffer using glBufferData and then writing data using glBufferSubData
    156  * prevents the bad behavior.
    157  *
    158  * There is a lot of uncertainty around this issue. In Chrome backgrounding
    159  * the tab somehow initiates this behavior and we don't know what the connection
    160  * is. Another observation is that Chrome's cmd buffer server will actually
    161  * create a buffer full of zeros when it sees a NULL data param (for security
    162  * reasons). If this is disabled and NULL is actually passed all the way to the
    163  * driver then the workaround doesn't help.
    164  *
    165  * The issue is tracked at:
    166  * http://code.google.com/p/chromium/issues/detail?id=114865
    167  *
    168  * When the workaround is enabled we will use the glBufferData / glBufferSubData
    169  * trick every 128 array buffer uploads.
    170  *
    171  * Hopefully we will understand this better and have a cleaner fix or get a
    172  * OS/driver level fix.
    173  */
    174 #define GR_GL_MAC_BUFFER_OBJECT_PERFOMANCE_WORKAROUND   \
    175     (GR_MAC_BUILD &&                                    \
    176      !GR_GL_USE_BUFFER_DATA_NULL_HINT)
    177 
    178 #endif
    179