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2 // Copyright 2018 Pixar
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4 // Licensed under the Apache License, Version 2.0 (the "Apache License")
5 // with the following modification; you may not use this file except in
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24 #ifndef PXR_IMAGING_GLF_CONTEXT_CAPS_H
25 #define PXR_IMAGING_GLF_CONTEXT_CAPS_H
26 
27 #include "pxr/pxr.h"
28 #include "pxr/imaging/glf/api.h"
29 #include "pxr/base/tf/singleton.h"
30 
31 
32 PXR_NAMESPACE_OPEN_SCOPE
33 
34 
35 /// \class GlfContextCaps
36 ///
37 /// This class is intended to be a cache of the capabilites
38 /// (resource limits and features) of the underlying
39 /// GL context.
40 ///
41 /// It serves two purposes.  Firstly to reduce driver
42 /// transition overhead of querying these values.
43 /// Secondly to provide access to these values from other
44 /// threads that don't have the context bound.
45 ///
46 /// In the event of failure (InitInstance() wasn't called
47 /// or an issue accessing the GL context), a reasonable
48 /// set of defaults, based on GL minimums, is provided.
49 ///
50 ///
51 /// TO DO (bug #124971):
52 ///   - LoadCaps() should be called whenever the context
53 ///     changes.
54 ///   - Provide a mechanism where other Hd systems can
55 ///     subscribe to when the caps changes, so they can
56 ///     update and invalidate.
57 ///
58 class GlfContextCaps
59 {
60 public:
61 
62     /// InitInstance queries the GL context for its capabilities.
63     /// It should be called by the application before using systems
64     /// that depend on the caps, such as Hydra.  A good example would be
65     /// to pair the call to initialize after a call to initialize GL
66     GLF_API
67     static void InitInstance();
68 
69     /// GetInstance() returns the filled capabilities structure.
70     /// This function will not populate the caps and will issue a
71     /// coding error if it hasn't been filled.
72     GLF_API
73     static const GlfContextCaps &GetInstance();
74 
75 
76 
77     // GL version
78     int glVersion;                    // 400 (4.0), 410 (4.1), ...
79 
80     // Whether or not we are running with core profile
81     bool coreProfile;
82 
83     // Max constants
84     int maxArrayTextureLayers;
85     int maxUniformBlockSize;
86     int maxShaderStorageBlockSize;
87     int maxTextureBufferSize;
88     int uniformBufferOffsetAlignment;
89 
90     // GL extensions (ordered by version)
91     bool arrayTexturesEnabled;        // EXT_texture_array                (3.0)
92     bool shaderStorageBufferEnabled;  // ARB_shader_storage_buffer_object (4.3)
93     bool bufferStorageEnabled;        // ARB_buffer_storage               (4.4)
94     bool directStateAccessEnabled;    // ARB_direct_state_access          (4.5)
95     bool multiDrawIndirectEnabled;    // ARB_multi_draw_indirect          (4.5)
96 
97     bool bindlessTextureEnabled;      // ARB_bindless_texture
98     bool bindlessBufferEnabled;       // NV_shader_buffer_load
99 
100     // GLSL version and extensions
101     int glslVersion;                  // 400, 410, ...
102     bool explicitUniformLocation;     // ARB_explicit_uniform_location    (4.3)
103     bool shadingLanguage420pack;      // ARB_shading_language_420pack     (4.2)
104     bool shaderDrawParametersEnabled; // ARB_shader_draw_parameters       (4.5)
105 
106     // workarounds for driver issues
107     bool copyBufferEnabled;
108 
109     bool floatingPointBuffersEnabled;
110 
111 private:
112     void _LoadCaps();
113     GlfContextCaps();
114     ~GlfContextCaps() = default;
115 
116     // Disallow copies
117     GlfContextCaps(const GlfContextCaps&) = delete;
118     GlfContextCaps& operator=(const GlfContextCaps&) = delete;
119 
120     friend class TfSingleton<GlfContextCaps>;
121 };
122 
123 GLF_API_TEMPLATE_CLASS(TfSingleton<GlfContextCaps>);
124 
125 PXR_NAMESPACE_CLOSE_SCOPE
126 
127 #endif // PXR_IMAGING_GLF_CONTEXT_CAPS_H
128 
129