forked from bartvdbraak/blender
a754e35198
* Split GPUDisplay into two classes. PathTraceDisplay to implement the Cycles side, and DisplayDriver to implement the host application side. The DisplayDriver is now a fully abstract base class, embedded in the PathTraceDisplay. * Move copy_pixels_to_texture implementation out of the host side into the Cycles side, since it can be implemented in terms of the texture buffer mapping. * Move definition of DeviceGraphicsInteropDestination into display driver header, so that we do not need to expose private device headers in the public API. * Add more detailed comments about how the DisplayDriver should be implemented. The "driver" terminology might not be obvious, but is also used in other renderers. Differential Revision: https://developer.blender.org/D12626
202 lines
8.0 KiB
C++
202 lines
8.0 KiB
C++
/*
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* Copyright 2021 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include "render/display_driver.h"
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#include "util/util_half.h"
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#include "util/util_thread.h"
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#include "util/util_types.h"
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#include "util/util_unique_ptr.h"
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CCL_NAMESPACE_BEGIN
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class BufferParams;
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/* PathTraceDisplay is used for efficient render buffer display.
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*
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* The host applications implements a DisplayDriver, storing a render pass in a GPU-side
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* textures. This texture is continuously updated by the path tracer and drawn by the host
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* application.
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*
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* PathTraceDisplay is a wrapper around the DisplayDriver, adding thread safety, state tracking
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* and error checking. */
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class PathTraceDisplay {
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public:
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PathTraceDisplay(unique_ptr<DisplayDriver> driver);
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virtual ~PathTraceDisplay() = default;
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/* Reset the display for the new state of render session. Is called whenever session is reset,
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* which happens on changes like viewport navigation or viewport dimension change.
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*
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* This call will configure parameters for a changed buffer and reset the texture state. */
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void reset(const BufferParams &buffer_params);
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/* --------------------------------------------------------------------
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* Update procedure.
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*
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* These calls indicates a desire of the caller to update content of the displayed texture. */
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/* Returns true when update is ready. Update should be finished with update_end().
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*
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* If false is returned then no update is possible, and no update_end() call is needed.
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*
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* The texture width and height denotes an actual resolution of the underlying render result. */
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bool update_begin(int texture_width, int texture_height);
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void update_end();
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/* Get currently configured texture size of the display (as configured by `update_begin()`. */
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int2 get_texture_size() const;
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/* --------------------------------------------------------------------
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* Texture update from CPU buffer.
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*
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* NOTE: The PathTraceDisplay should be marked for an update being in process with
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* `update_begin()`.
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*
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* Most portable implementation, which must be supported by all platforms. Might not be the most
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* efficient one.
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*/
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/* Copy buffer of rendered pixels of a given size into a given position of the texture.
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*
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* This function does not acquire a lock. The reason for this is is to allow use of this function
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* for partial updates from different devices. In this case the caller will acquire the lock
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* once, update all the slices and release
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* the lock once. This will ensure that draw() will never use partially updated texture. */
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void copy_pixels_to_texture(
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const half4 *rgba_pixels, int texture_x, int texture_y, int pixels_width, int pixels_height);
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/* --------------------------------------------------------------------
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* Texture buffer mapping.
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*
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* This functionality is used to update GPU-side texture content without need to maintain CPU
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* side buffer on the caller.
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*
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* NOTE: The PathTraceDisplay should be marked for an update being in process with
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* `update_begin()`.
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*
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* NOTE: Texture buffer can not be mapped while graphics interoperability is active. This means
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* that `map_texture_buffer()` is not allowed between `graphics_interop_begin()` and
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* `graphics_interop_end()` calls.
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*/
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/* Map pixels memory form texture to a buffer available for write from CPU. Width and height will
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* define a requested size of the texture to write to.
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* Upon success a non-null pointer is returned and the texture buffer is to be unmapped.
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* If an error happens during mapping, or if mapping is not supported by this GPU display a
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* null pointer is returned and the buffer is NOT to be unmapped.
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*
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* NOTE: Usually the implementation will rely on a GPU context of some sort, and the GPU context
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* is often can not be bound to two threads simultaneously, and can not be released from a
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* different thread. This means that the mapping API should be used from the single thread only,
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*/
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half4 *map_texture_buffer();
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void unmap_texture_buffer();
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/* --------------------------------------------------------------------
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* Graphics interoperability.
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*
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* A special code path which allows to update texture content directly from the GPU compute
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* device. Complementary part of DeviceGraphicsInterop.
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*
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* NOTE: Graphics interoperability can not be used while the texture buffer is mapped. This means
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* that `graphics_interop_get()` is not allowed between `map_texture_buffer()` and
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* `unmap_texture_buffer()` calls. */
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/* Get PathTraceDisplay graphics interoperability information which acts as a destination for the
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* device API. */
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DisplayDriver::GraphicsInterop graphics_interop_get();
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/* (De)activate GPU display for graphics interoperability outside of regular display update
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* routines. */
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void graphics_interop_activate();
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void graphics_interop_deactivate();
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/* --------------------------------------------------------------------
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* Drawing.
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*/
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/* Clear the texture by filling it with all zeroes.
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*
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* This call might happen in parallel with draw, but can never happen in parallel with the
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* update.
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*
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* The actual zeroing can be deferred to a later moment. What is important is that after clear
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* and before pixels update the drawing texture will be fully empty, and that partial update
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* after clear will write new pixel values for an updating area, leaving everything else zeroed.
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*
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* If the GPU display supports graphics interoperability then the zeroing the display is to be
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* delegated to the device via the `DisplayDriver::GraphicsInterop`. */
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void clear();
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/* Draw the current state of the texture.
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*
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* Returns true if this call did draw an updated state of the texture. */
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bool draw();
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private:
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/* Display driver implemented by the host application. */
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unique_ptr<DisplayDriver> driver_;
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/* Current display parameters */
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thread_mutex mutex_;
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DisplayDriver::Params params_;
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/* Mark texture as its content has been updated.
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* Used from places which knows that the texture content has been brought up-to-date, so that the
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* drawing knows whether it can be performed, and whether drawing happened with an up-to-date
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* texture state. */
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void mark_texture_updated();
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/* State of the update process. */
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struct {
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/* True when update is in process, indicated by `update_begin()` / `update_end()`. */
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bool is_active = false;
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} update_state_;
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/* State of the texture, which is needed for an integration with render session and interactive
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* updates and navigation. */
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struct {
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/* Denotes whether possibly existing state of GPU side texture is still usable.
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* It will not be usable in cases like render border did change (in this case we don't want
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* previous texture to be rendered at all).
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*
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* However, if only navigation or object in scene did change, then the outdated state of the
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* texture is still usable for draw, preventing display viewport flickering on navigation and
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* object modifications. */
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bool is_usable = false;
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/* Texture is considered outdated after `reset()` until the next call of
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* `copy_pixels_to_texture()`. */
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bool is_outdated = true;
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/* Texture size in pixels. */
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int2 size = make_int2(0, 0);
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} texture_state_;
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/* State of the texture buffer. Is tracked to perform sanity checks. */
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struct {
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/* True when the texture buffer is mapped with `map_texture_buffer()`. */
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bool is_mapped = false;
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} texture_buffer_state_;
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};
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CCL_NAMESPACE_END
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