79 lines
2.5 KiB
Plaintext
79 lines
2.5 KiB
Plaintext
////
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- Copyright (c) 2024, Google
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-
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- SPDX-License-Identifier: Apache-2.0
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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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////
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= Order-independent transparency with depth peeling
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ifdef::site-gen-antora[]
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TIP: The source for this sample can be found in the https://github.com/KhronosGroup/Vulkan-Samples/tree/main/samples/api/oit_depth_peeling[Khronos Vulkan samples github repository].
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endif::[]
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:pp: {plus}{plus}
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image::./images/sample.png[Sample]
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== Overview
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This sample implements an order-independent transparency (OIT) algorithm using depth peeling.
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It renders a single torus whose opacity can be controlled via the UI.
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It produces pixel-perfect results.
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It is based on the https://developer.download.nvidia.com/assets/gamedev/docs/OrderIndependentTransparency.pdf[original paper] from Cass Everitt.
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== Algorithm
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The OIT algorithm consists of several _gather_ passes followed by one _combine_ pass.
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Each _gather_ pass renders one layer of transparent geometry.
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The first pass renders the first layer, the second pass the second layer, etc.
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The N^th^ layer consists of all the N^th^ fragments of each pixel when the fragments are ordered from front to back.
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The _combine_ pass is a screen-space operation.
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It merges the layer images from back to front to produce the final result.
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The algorithm can produce pixel-perfect results, even with intersecting geometry.
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When there are more geometry layers than gather passes, the backmost layers get skipped, but the visual results stay stable (i.e. no flickering pixels).
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== Options
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[cols="2,4,4"]
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|===
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| Option | Description | Comments
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| Camera auto-rotation
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| Enable the automatic rotation of the camera
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| Background grayscale
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| Specify the grayscale value by which the background color is multiplied (0.0 to 1.0)
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| Object alpha
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| Specify the opacity of the transparent object (0.0 to 1.0)
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| Front layer index
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| The first layer to be rendered (0 to 7).
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| Back layer index
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| The last layer to be rendered (0 to 7).
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| This cannot be less that the front layer index.
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|===
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