#endif
};
struct ScreenSpaceHiZ RaymarchInput
struct ScreenSpaceRaymarchInput
{
float3 rayOriginWS; // Ray origin (WS)
float3 rayDirWS; // Ray direction (WS)
// Check whether the depth of the ray is above the sampled depth
// Arguments are inversed linear depth
bool IsPositionAboveDepth(float r ayDepth, float invLinearDepth)
bool IsPositionAboveDepth(float invR ayDepth, float invLinearDepth)
return r ayDepth > invLinearDepth;
return invR ayDepth > invLinearDepth;
}
// Sample the Depth buffer at a specific mip and linear depth
#define SSRT_FUNC(name, SSRTID) name ## SSRTID
CBUFFER_START(SSRT_FUNC(UnityScreenSpaceRaymarching, SSRTID))
int SSRT_SETTING(RayLevel, SSRTID);
int SSRT_SETTING(RayMaxLinearIterations, SSRTID);
#ifdef DEBUG_DISPLAY
int SSRT_SETTING(DebuggedAlgorithm, SSRTID);
#endif
CBUFFER_END
bool SSRT_FUNC(ScreenSpaceProxyRaycast, SSRTID)(
#ifdef DEBUG_DISPLAY
DebugComputeCommonOutput(input.rayDirWS, hitSuccessful, hit);
if (input.debug && _DebugScreenSpaceTracingData[0].tracingModel == -1)
if (input.debug
&& _DebugScreenSpaceTracingData[0].tracingModel == -1
&& SSRT_SETTING(DebuggedAlgorithm, SSRTID) == PROJECTIONMODEL_PROXY
)
{
ScreenSpaceTracingDebug debug;
ZERO_INITIALIZE(ScreenSpaceTracingDebug, debug);
}
// -------------------------------------------------
// Algorithm: Linear Raymarching
// -------------------------------------------------
// Based on Digital Differential Analyzer and Morgan McGuire's Screen Space Ray Tracing (http://casual-effects.blogspot.fr/2014/08/screen-space-ray-tracing.html)
// Linear raymarching algorithm with precomputed properties
bool SSRT_FUNC(_ScreenSpaceLinearRaymarch, SSRTID)(
ScreenSpaceRaymarchInput input,
uint inputMaxIterations,
float3 startPositionSS,
float3 raySS,
uint2 bufferSize,
out ScreenSpaceRayHit hit
)
{
ZERO_INITIALIZE(ScreenSpaceRayHit, hit);
bool hitSuccessful = true;
uint iteration = 0u;
int mipLevel = min(max(SSRT_SETTING(RayLevel, SSRTID), 0), int(_DepthPyramidScale.z));
uint maxIterations = min(inputMaxIterations, uint(SSRT_SETTING(RayMaxIterations, SSRTID)));
float3 positionSS = startPositionSS;
raySS /= max(abs(raySS.x), abs(raySS.y));
raySS.xy *= int2(1, 1) << mipLevel;
// Offset by half a texel
positionSS += raySS * 0.5;
#ifdef DEBUG_DISPLAY
float3 debugIterationPositionSS = positionSS;
float debugIterationLinearDepthBuffer = 0;
uint debugIteration = iteration;
#endif
float invHiZDepth = 0;
for (iteration = 0u; iteration < maxIterations; ++iteration)
{
positionSS += raySS;
// Sampled as 1/Z so it interpolate properly in screen space.
invHiZDepth = LoadInvDepth(positionSS.xy, mipLevel);
#ifdef DEBUG_DISPLAY
// Fetch post iteration debug values
if (input.debug && _DebugStep >= iteration)
{
debugIterationPositionSS = positionSS;
debugIterationLinearDepthBuffer = 1 / invHiZDepth;
debugIteration = iteration;
}
#endif
if (!IsPositionAboveDepth(positionSS.z, invHiZDepth))
break;
// Check if we are out of the buffer
if (any(int2(positionSS.xy) > int2(bufferSize))
|| any(positionSS.xy < 0)
)
{
hitSuccessful = false;
break;
}
}
if (iteration >= maxIterations)
hitSuccessful = false;
hit.linearDepth = 1 / positionSS.z;
hit.positionNDC = float2(positionSS.xy) / float2(bufferSize);
hit.positionSS = uint2(positionSS.xy);
#ifdef DEBUG_DISPLAY
DebugComputeCommonOutput(input.rayDirWS, hitSuccessful, hit);
if (input.debug
&& _DebugScreenSpaceTracingData[0].tracingModel == -1
&& SSRT_SETTING(DebuggedAlgorithm, SSRTID) == PROJECTIONMODEL_LINEAR
)
{
// Build debug structure
ScreenSpaceTracingDebug debug;
ZERO_INITIALIZE(ScreenSpaceTracingDebug, debug);
debug.tracingModel = PROJECTIONMODEL_LINEAR;
debug.loopStartPositionSSX = uint(startPositionSS.x);
debug.loopStartPositionSSY = uint(startPositionSS.y);
debug.loopStartLinearDepth = 1 / startPositionSS.z;
debug.loopRayDirectionSS = raySS;
debug.loopIterationMax = iteration;
debug.iterationPositionSS = debugIterationPositionSS;
debug.iterationMipLevel = mipLevel;
debug.iteration = debugIteration;
debug.iterationLinearDepthBuffer = debugIterationLinearDepthBuffer;
debug.endHitSuccess = hitSuccessful;
debug.endLinearDepth = hit.linearDepth;
debug.endPositionSSX = hit.positionSS.x;
debug.endPositionSSY = hit.positionSS.y;
debug.iterationCellSizeW = 1 << mipLevel;
debug.iterationCellSizeH = 1 << mipLevel;
_DebugScreenSpaceTracingData[0] = debug;
}
#endif
return hitSuccessful;
}
bool SSRT_FUNC(ScreenSpaceLinearRaymarch, SSRTID)(
ScreenSpaceRaymarchInput input,
out ScreenSpaceRayHit hit
)
{
uint2 bufferSize = uint2(_DepthPyramidSize.xy);
float3 startPositionSS;
float3 raySS;
CalculateRaySS(
input.rayOriginWS,
input.rayDirWS,
bufferSize,
startPositionSS,
raySS
);
return SSRT_FUNC(_ScreenSpaceLinearRaymarch, SSRTID)(
input,
input.maxIterations,
startPositionSS,
raySS,
bufferSize,
hit
);
}
// -------------------------------------------------
// Algorithm: HiZ raymarching
// -------------------------------------------------
ScreenSpaceHiZRaymarchInput input,
ScreenSpaceRaymarchInput input,
out ScreenSpaceRayHit hit
)
{
startPositionSS,
raySS
);
if (SSRT_FUNC(_ScreenSpaceLinearRaymarch, SSRTID)(
input,
SSRT_SETTING(RayMaxLinearIterations, SSRTID),
startPositionSS,
raySS,
bufferSize,
hit
))
return true;
startPositionSS = float3(hit.positionSS, 1 / hit.linearDepth);
#ifdef DEBUG_DISPLAY
// Initialize debug variables
hit
);
if (input.debug && _DebugScreenSpaceTracingData[0].tracingModel == -1)
if (input.debug
&& _DebugScreenSpaceTracingData[0].tracingModel == -1
&& SSRT_SETTING(DebuggedAlgorithm, SSRTID) == PROJECTIONMODEL_HI_Z
)
{
// Build debug structure
ScreenSpaceTracingDebug debug;
Frédéric Vauchelles
7 年前