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| Resources and derived objects |
| ============================= |
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| Resources represent objects that hold data: textures and buffers. |
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| They are mostly modelled after the resources in Direct3D 10/11, but with a |
| different transfer/update mechanism, and more features for OpenGL support. |
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| Resources can be used in several ways, and it is required to specify all planned uses through an appropriate set of bind flags. |
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| TODO: write much more on resources |
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| Transfers |
| --------- |
| |
| Transfers are the mechanism used to access resources with the CPU. |
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| OpenGL: OpenGL supports mapping buffers and has inline transfer functions for both buffers and textures |
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| D3D11: D3D11 lacks transfers, but has special resource types that are mappable to the CPU address space |
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| TODO: write much more on transfers |
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| Resource targets |
| ---------------- |
| |
| Resource targets determine the type of a resource. |
| |
| Note that drivers may not actually have the restrictions listed regarding |
| coordinate normalization and wrap modes, and in fact efficient OpenCL |
| support will probably require drivers that don't have any of them, which |
| will probably be advertised with an appropriate cap. |
| |
| TODO: document all targets. Note that both 3D and cube have restrictions |
| that depend on the hardware generation. |
| |
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| PIPE_BUFFER |
| ^^^^^^^^^^^ |
| |
| Buffer resource: can be used as a vertex, index, constant buffer |
| (appropriate bind flags must be requested). |
| |
| Buffers do not really have a format, it's just bytes, but they are required |
| to have their type set to a R8 format (without a specific "just byte" format, |
| R8_UINT would probably make the most sense, but for historic reasons R8_UNORM |
| is ok too). (This is just to make some shared buffer/texture code easier so |
| format size can be queried.) |
| width0 serves as size, most other resource properties don't apply but must be |
| set appropriately (depth0/height0/array_size must be 1, last_level 0). |
| |
| They can be bound to stream output if supported. |
| TODO: what about the restrictions lifted by the several later GL transform feedback extensions? How does one advertise that in Gallium? |
| |
| They can be also be bound to a shader stage (for sampling) as usual by |
| creating an appropriate sampler view, if the driver supports PIPE_CAP_TEXTURE_BUFFER_OBJECTS. |
| This supports larger width than a 1d texture would |
| (TODO limit currently unspecified, minimum must be at least 65536). |
| Only the "direct fetch" sample opcodes are supported (TGSI_OPCODE_TXF, |
| TGSI_OPCODE_SAMPLE_I) so the sampler state (coord wrapping etc.) |
| is mostly ignored (with SAMPLE_I there's no sampler state at all). |
| |
| They can be also be bound to the framebuffer (only as color render target, not |
| depth buffer, also there cannot be a depth buffer bound at the same time) as usual |
| by creating an appropriate view (this is not usable in OpenGL). |
| TODO there's no CAP bit currently for this, there's also unspecified size etc. limits |
| TODO: is there any chance of supporting GL pixel buffer object acceleration with this? |
| |
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| OpenGL: vertex buffers in GL 1.5 or GL_ARB_vertex_buffer_object |
| |
| - Binding to stream out requires GL 3.0 or GL_NV_transform_feedback |
| - Binding as constant buffers requires GL 3.1 or GL_ARB_uniform_buffer_object |
| - Binding to a sampling stage requires GL 3.1 or GL_ARB_texture_buffer_object |
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| D3D11: buffer resources |
| - Binding to a render target requires D3D_FEATURE_LEVEL_10_0 |
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| PIPE_TEXTURE_1D / PIPE_TEXTURE_1D_ARRAY |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1D surface accessed with normalized coordinates. |
| 1D array textures are supported depending on PIPE_CAP_MAX_TEXTURE_ARRAY_LAYERS. |
| |
| - If PIPE_CAP_NPOT_TEXTURES is not supported, |
| width must be a power of two |
| - height0 must be 1 |
| - depth0 must be 1 |
| - array_size must be 1 for PIPE_TEXTURE_1D |
| - Mipmaps can be used |
| - Must use normalized coordinates |
| |
| OpenGL: GL_TEXTURE_1D in GL 1.0 |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to GL 2.0 or GL_ARB_texture_non_power_of_two |
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| D3D11: 1D textures in D3D_FEATURE_LEVEL_10_0 |
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| PIPE_TEXTURE_RECT |
| ^^^^^^^^^^^^^^^^^ |
| 2D surface with OpenGL GL_TEXTURE_RECTANGLE semantics. |
| |
| - depth0 must be 1 |
| - array_size must be 1 |
| - last_level must be 0 |
| - Must use unnormalized coordinates |
| - Must use a clamp wrap mode |
| |
| OpenGL: GL_TEXTURE_RECTANGLE in GL 3.1 or GL_ARB_texture_rectangle or GL_NV_texture_rectangle |
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| OpenCL: can create OpenCL images based on this, that can then be sampled arbitrarily |
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| D3D11: not supported (only PIPE_TEXTURE_2D with normalized coordinates is supported) |
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| PIPE_TEXTURE_2D / PIPE_TEXTURE_2D_ARRAY |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 2D surface accessed with normalized coordinates. |
| 2D array textures are supported depending on PIPE_CAP_MAX_TEXTURE_ARRAY_LAYERS. |
| |
| - If PIPE_CAP_NPOT_TEXTURES is not supported, |
| width and height must be powers of two |
| - depth0 must be 1 |
| - array_size must be 1 for PIPE_TEXTURE_2D |
| - Mipmaps can be used |
| - Must use normalized coordinates |
| - No special restrictions on wrap modes |
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| OpenGL: GL_TEXTURE_2D in GL 1.0 |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to GL 2.0 or GL_ARB_texture_non_power_of_two |
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| OpenCL: can create OpenCL images based on this, that can then be sampled arbitrarily |
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| D3D11: 2D textures |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to D3D_FEATURE_LEVEL_9_3 |
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| PIPE_TEXTURE_3D |
| ^^^^^^^^^^^^^^^ |
| |
| 3-dimensional array of texels. |
| Mipmap dimensions are reduced in all 3 coordinates. |
| |
| - If PIPE_CAP_NPOT_TEXTURES is not supported, |
| width, height and depth must be powers of two |
| - array_size must be 1 |
| - Must use normalized coordinates |
| |
| OpenGL: GL_TEXTURE_3D in GL 1.2 or GL_EXT_texture3D |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to GL 2.0 or GL_ARB_texture_non_power_of_two |
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| D3D11: 3D textures |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to D3D_FEATURE_LEVEL_10_0 |
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| PIPE_TEXTURE_CUBE / PIPE_TEXTURE_CUBE_ARRAY |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| Cube maps consist of 6 2D faces. |
| The 6 surfaces form an imaginary cube, and sampling happens by mapping an |
| input 3-vector to the point of the cube surface in that direction. |
| Cube map arrays are supported depending on PIPE_CAP_CUBE_MAP_ARRAY. |
| |
| Sampling may be optionally seamless if a driver supports it (PIPE_CAP_SEAMLESS_CUBE_MAP), |
| resulting in filtering taking samples from multiple surfaces near to the edge. |
| |
| - Width and height must be equal |
| - depth0 must be 1 |
| - array_size must be a multiple of 6 |
| - If PIPE_CAP_NPOT_TEXTURES is not supported, |
| width and height must be powers of two |
| - Must use normalized coordinates |
| |
| OpenGL: GL_TEXTURE_CUBE_MAP in GL 1.3 or EXT_texture_cube_map |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to GL 2.0 or GL_ARB_texture_non_power_of_two |
| - Seamless cube maps require GL 3.2 or GL_ARB_seamless_cube_map or GL_AMD_seamless_cubemap_per_texture |
| - Cube map arrays require GL 4.0 or GL_ARB_texture_cube_map_array |
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| D3D11: 2D array textures with the D3D11_RESOURCE_MISC_TEXTURECUBE flag |
| |
| - PIPE_CAP_NPOT_TEXTURES is equivalent to D3D_FEATURE_LEVEL_10_0 |
| - Cube map arrays require D3D_FEATURE_LEVEL_10_1 |
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| Surfaces |
| -------- |
| |
| Surfaces are views of a resource that can be bound as a framebuffer to serve as the render target or depth buffer. |
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| TODO: write much more on surfaces |
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| OpenGL: FBOs are collections of surfaces in GL 3.0 or GL_ARB_framebuffer_object |
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| D3D11: render target views and depth/stencil views |
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| Sampler views |
| ------------- |
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| Sampler views are views of a resource that can be bound to a pipeline stage to be sampled from shaders. |
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| TODO: write much more on sampler views |
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| OpenGL: texture objects are actually sampler view and resource in a single unit |
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| D3D11: shader resource views |