mirror of
https://github.com/ncblakely/GiantsTools
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96 lines
2.8 KiB
HLSL
96 lines
2.8 KiB
HLSL
//
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// Copyright (c) Microsoft. All rights reserved.
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// This code is licensed under the MIT License (MIT).
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// THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
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// ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
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// IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
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// PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
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//
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// Developed by Minigraph
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//
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// Author: James Stanard
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//
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#ifndef __PIXEL_PACKING_VELOCITY_HLSLI__
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#define __PIXEL_PACKING_VELOCITY_HLSLI__
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#if 1
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// This is a custom packing that devotes 10 bits each to X and Y velocity but 12 bits to Z velocity. Floats
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// are used instead of SNORM to increase precision around small deltas, which are the majority of deltas.
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// With TAA and Motion Blur, velocities are clamped, giving little reason to express them precisely in terms
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// of the size of the screen.
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#define packed_velocity_t uint
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// Designed to compress (-256.0, +256.0) with a signed 6e3 float
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uint PackXY( float x )
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{
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uint signbit = asuint(x) >> 31;
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x = clamp(abs(x / 32768.0), 0, asfloat(0x3BFFE000));
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return (f32tof16(x) + 8) >> 4 | signbit << 9;
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}
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float UnpackXY( uint x )
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{
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return f16tof32((x & 0x1FF) << 4 | (x >> 9) << 15) * 32768.0;
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}
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// Designed to compress (-1.0, 1.0) with a signed 8e3 float
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uint PackZ( float x )
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{
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uint signbit = asuint(x) >> 31;
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x = clamp(abs(x / 128.0), 0, asfloat(0x3BFFE000));
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return (f32tof16(x) + 2) >> 2 | signbit << 11;
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}
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float UnpackZ( uint x )
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{
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return f16tof32((x & 0x7FF) << 2 | (x >> 11) << 15) * 128.0;
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}
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// Pack the velocity to write to R10G10B10A2_UNORM
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packed_velocity_t PackVelocity( float3 Velocity )
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{
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return PackXY(Velocity.x) | PackXY(Velocity.y) << 10 | PackZ(Velocity.z) << 20;
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}
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// Unpack the velocity from R10G10B10A2_UNORM
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float3 UnpackVelocity( packed_velocity_t Velocity )
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{
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return float3(UnpackXY(Velocity & 0x3FF), UnpackXY((Velocity >> 10) & 0x3FF), UnpackZ(Velocity >> 20));
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}
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#elif 1
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#define packed_velocity_t float4
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// Pack the velocity to write to R10G10B10A2_UNORM
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packed_velocity_t PackVelocity( float3 Velocity )
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{
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// Stretch dx,dy from [-64, 63.875] to [-512, 511] to [-0.5, 0.5) to [0, 1)
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// Velocity.xy = (0,0) must be representable.
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return float4(Velocity * float3(8, 8, 4096) / 1024.0 + 512 / 1023.0, 0);
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}
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// Unpack the velocity from R10G10B10A2_UNORM
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float3 UnpackVelocity( packed_velocity_t Velocity )
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{
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return (Velocity.xyz - 512.0 / 1023.0) * float3(1024, 1024, 2) / 8.0;
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}
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#else
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#define packed_velocity_t float4
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// Pack the velocity to write to R16G16B16A16_FLOAT
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packed_velocity_t PackVelocity( float3 Velocity )
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{
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return float4(Velocity * float3(16, 16, 32*1024), 0);
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}
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// Unpack the velocity from R10G10B10A2_UNORM
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float3 UnpackVelocity( packed_velocity_t Velocity )
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{
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return Velocity.xyz / float3(16, 16, 32*1024);
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}
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#endif
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#endif // __PIXEL_PACKING_HLSLI__
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