Similar to using larger buffers and sub-allocating from those, a developer could use texture arrays for popular dimensions and re-use individual layers. The developer can also use it as view on a sub-resource, for example individual texture layer or mipmap in an array texture.
ARB_texture_view (core 4.3) introduced the concept of casting texture formats to different types as long as they have the same texel size. glTextureStorage is the better alternative for the driver. The classic glTexImage never “knew” how many mip-maps would actually be specified, often causing lazy allocation. ARB_texture_storage (core 4.2) provides immutable textures whose definition is complete up-front. We also encourage the use of few but rather large buffers as suggested in the memory management blog post. This would allow an identical workflow to Vulkan. Ideally the developer uses persistent mapped buffers for all buffers that he expects to for reading or writing access on the CPU. ARB_buffer_storage (core 4.4) should be preferred over the classic glBufferData, as it gives better usage hints than glBufferData. Some of these functions may also be available under EXT_direct_state_access, the primary difference between ARB and EXT is that ARB requires the use of glCreate”Resource” rather than working from glGen”Resource” object handles. In this case the “indirection” by passing the object handle, may cause additional work. “Bind to Edit” can still be beneficial in the hot loop, for example when the same buffer is updated very often by glBufferSubData, or glUniforms for the active program are changed. glBindBuffer would most likely only be used with the ELEMENT_ARRAY, DRAW_INDIRECT in the rendering loop. glBindBuffersBase / glBindBuffersRange for UNIFORM, SHADER_STORAGE, ATOMIC_COUNTER, TRANSFORM_FEEDBACK. Within the rendering hot loop the new set of binding calls is encouraged, as they only affect rendering state: Using DSA makes object manipulation cleaner as it doesn’t affect the binding state used for rendering, therefore is also middleware friendly. Vulkan follows an object-oriented design and we always manipulate objects directly with their handles.ĪRB_direct_state_access (DSA), OpenGL 4.5 core, allows direct manipulation of objects (textures, buffers, fbos…) rather than the classic “bind to edit”. With additional extensions those fast paths can become even more general purpose and similar to Vulkan. These results show that very fast paths in OpenGL exist. The “multi draw indirect” renderer has to use dynamic indexing into larger buffers to access the shader parameters per draw-call, which may not work as well for less simple data. Renderers with the “ubo” tag pass object matrix and material information by binding UBO ranges. The test draws around 44k objects which have only few triangles per object (typical CPU-limited scenario) and is not using hardware instancing. The cadscene sample was used to compare different rendering techniques in a scenario where state changes where minimized. OpenGL rendering statistics from a CAD scene benchmark. Here are some tips that will make a transition to Vulkan smoother and help to improve performance in OpenGL as well, many of which are also known as “AZDO” techniques. Literally translating a traditional OpenGL/state-machine based renderer to Vulkan is possible, but most likely ends up in lower performance. Even if going Vulkan is not an option at the moment, its concepts do show where modern rendering architectures are heading. In a previous blog post we have discussed the usage scenarios of Vulkan and OpenGL.
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