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CLK/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
Thomas Harte e7ce03c418 Attempts to ensure initial finalised line texture state.
This was an attempt to remove the vertical line on the left of a composite display. Obviously the cause is not as suspected.
2020-09-09 13:15:21 -04:00

564 lines
22 KiB
Metal

//
// ScanTarget.metal
// Clock Signal
//
// Created by Thomas Harte on 04/08/2020.
// Copyright © 2020 Thomas Harte. All rights reserved.
//
#include <metal_stdlib>
using namespace metal;
// TODO: I'm being very loose, so far, in use of alpha. Sometimes it's 0.64, somtimes its 1.0.
// Apply some rigour, for crying out loud.
struct Uniforms {
// This is used to scale scan positions, i.e. it provides the range
// for mapping from scan-style integer positions into eye space.
int2 scale;
// Applies a multiplication to all cyclesSinceRetrace values.
float cycleMultiplier;
// This provides the intended height of a scan, in eye-coordinate terms.
float lineWidth;
// Provides a scaling factor in order to preserve 4:3 central content.
float aspectRatioMultiplier;
// Provides zoom and offset to scale the source data.
float zoom;
float2 offset;
// Provides conversions to and from RGB for the active colour space.
half3x3 toRGB;
half3x3 fromRGB;
// Describes the filter in use for chroma filtering; it'll be
// 15 coefficients but they're symmetrical around the centre.
half3 chromaKernel[8];
// Describes the filter in use for luma filtering; 15 coefficients
// symmetrical around the centre.
half lumaKernel[8];
// Sets the opacity at which output strips are drawn.
half outputAlpha;
// Sets the gamma power to which output colours are raised.
half outputGamma;
// Sets a brightness multiplier for output colours.
half outputMultiplier;
};
namespace {
constexpr sampler standardSampler( coord::pixel,
address::clamp_to_edge, // Although arbitrary, stick with this address mode for compatibility all the way to MTLFeatureSet_iOS_GPUFamily1_v1.
filter::nearest);
constexpr sampler linearSampler( coord::pixel,
address::clamp_to_edge, // Although arbitrary, stick with this address mode for compatibility all the way to MTLFeatureSet_iOS_GPUFamily1_v1.
filter::linear);
}
// MARK: - Structs used for receiving data from the emulation.
// This is intended to match the net effect of `Scan` as defined by the BufferingScanTarget.
struct Scan {
struct EndPoint {
uint16_t position[2];
uint16_t dataOffset;
int16_t compositeAngle;
uint16_t cyclesSinceRetrace;
} endPoints[2];
uint8_t compositeAmplitude;
uint16_t dataY;
uint16_t line;
};
// This matches the BufferingScanTarget's `Line`.
struct Line {
struct EndPoint {
uint16_t position[2];
int16_t compositeAngle;
uint16_t cyclesSinceRetrace;
} endPoints[2];
uint8_t compositeAmplitude;
uint16_t line;
};
// MARK: - Intermediate structs.
struct SourceInterpolator {
float4 position [[position]];
float2 textureCoordinates;
float unitColourPhase; // i.e. one unit per circle.
float colourPhase; // i.e. 2*pi units per circle, just regular radians.
float colourAmplitude [[flat]];
};
struct CopyInterpolator {
float4 position [[position]];
float2 textureCoordinates;
};
// MARK: - Vertex shaders.
float2 textureLocation(constant Line *line, float offset, constant Uniforms &uniforms) {
return float2(
uniforms.cycleMultiplier * mix(line->endPoints[0].cyclesSinceRetrace, line->endPoints[1].cyclesSinceRetrace, offset),
line->line + 0.5f);
}
float2 textureLocation(constant Scan *scan, float offset, constant Uniforms &) {
return float2(
mix(scan->endPoints[0].dataOffset, scan->endPoints[1].dataOffset, offset),
scan->dataY + 0.5f);
}
template <typename Input> SourceInterpolator toDisplay(
constant Uniforms &uniforms [[buffer(1)]],
constant Input *inputs [[buffer(0)]],
uint instanceID [[instance_id]],
uint vertexID [[vertex_id]]) {
SourceInterpolator output;
// Get start and end vertices in regular float2 form.
const float2 start = float2(
float(inputs[instanceID].endPoints[0].position[0]) / float(uniforms.scale.x),
float(inputs[instanceID].endPoints[0].position[1]) / float(uniforms.scale.y)
);
const float2 end = float2(
float(inputs[instanceID].endPoints[1].position[0]) / float(uniforms.scale.x),
float(inputs[instanceID].endPoints[1].position[1]) / float(uniforms.scale.y)
);
// Calculate the tangent and normal.
const float2 tangent = (end - start);
const float2 normal = float2(tangent.y, -tangent.x) / length(tangent);
// Load up the colour details.
output.colourAmplitude = float(inputs[instanceID].compositeAmplitude) / 255.0f;
output.unitColourPhase = mix(
float(inputs[instanceID].endPoints[0].compositeAngle),
float(inputs[instanceID].endPoints[1].compositeAngle),
float((vertexID&2) >> 1)
) / 64.0f;
output.colourPhase = 2.0f * 3.141592654f * output.unitColourPhase;
// Hence determine this quad's real shape, using vertexID to pick a corner.
// position2d is now in the range [0, 1].
float2 position2d = start + (float(vertexID&2) * 0.5f) * tangent + (float(vertexID&1) - 0.5f) * normal * uniforms.lineWidth;
// Apply the requested offset and zoom, to map the desired area to the range [0, 1].
position2d = (position2d + uniforms.offset) * uniforms.zoom;
// Remap from [0, 1] to Metal's [-1, 1] and then apply the aspect ratio correction.
position2d = (position2d * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f)) * float2(uniforms.aspectRatioMultiplier, 1.0f);
output.position = float4(
position2d,
0.0f,
1.0f
);
output.textureCoordinates = textureLocation(&inputs[instanceID], float((vertexID&2) >> 1), uniforms);
return output;
}
// These next two assume the incoming geometry to be a four-vertex triangle strip; each instance will therefore
// produce a quad.
vertex SourceInterpolator scanToDisplay( constant Uniforms &uniforms [[buffer(1)]],
constant Scan *scans [[buffer(0)]],
uint instanceID [[instance_id]],
uint vertexID [[vertex_id]]) {
return toDisplay(uniforms, scans, instanceID, vertexID);
}
vertex SourceInterpolator lineToDisplay( constant Uniforms &uniforms [[buffer(1)]],
constant Line *lines [[buffer(0)]],
uint instanceID [[instance_id]],
uint vertexID [[vertex_id]]) {
return toDisplay(uniforms, lines, instanceID, vertexID);
}
// This assumes that it needs to generate endpoints for a line segment.
vertex SourceInterpolator scanToComposition( constant Uniforms &uniforms [[buffer(1)]],
constant Scan *scans [[buffer(0)]],
uint instanceID [[instance_id]],
uint vertexID [[vertex_id]],
texture2d<float> texture [[texture(0)]]) {
SourceInterpolator result;
// Populate result as if direct texture access were available.
result.position.x = uniforms.cycleMultiplier * mix(scans[instanceID].endPoints[0].cyclesSinceRetrace, scans[instanceID].endPoints[1].cyclesSinceRetrace, float(vertexID));
result.position.y = scans[instanceID].line;
result.position.zw = float2(0.0f, 1.0f);
result.textureCoordinates.x = mix(scans[instanceID].endPoints[0].dataOffset, scans[instanceID].endPoints[1].dataOffset, float(vertexID));
result.textureCoordinates.y = scans[instanceID].dataY;
result.unitColourPhase = mix(
float(scans[instanceID].endPoints[0].compositeAngle),
float(scans[instanceID].endPoints[1].compositeAngle),
float(vertexID)
) / 64.0f;
result.colourPhase = 2.0f * 3.141592654f * result.unitColourPhase;
result.colourAmplitude = float(scans[instanceID].compositeAmplitude) / 255.0f;
// Map position into eye space, allowing for target texture dimensions.
const float2 textureSize = float2(texture.get_width(), texture.get_height());
result.position.xy =
((result.position.xy + float2(0.0f, 0.5f)) / textureSize)
* float2(2.0f, -2.0f) + float2(-1.0f, 1.0f);
return result;
}
vertex CopyInterpolator copyVertex(uint vertexID [[vertex_id]], texture2d<float> texture [[texture(0)]]) {
CopyInterpolator vert;
const uint x = vertexID & 1;
const uint y = (vertexID >> 1) & 1;
vert.textureCoordinates = float2(
x * texture.get_width(),
y * texture.get_height()
);
vert.position = float4(
float(x) * 2.0 - 1.0,
1.0 - float(y) * 2.0,
0.0,
1.0
);
return vert;
}
// MARK: - Various input format conversion samplers.
float2 quadrature(float phase) {
return float2(cos(phase), sin(phase));
}
float4 composite(float level, float2 quadrature, float amplitude) {
return float4(
level,
float2(0.5f) + quadrature*0.5f,
amplitude
);
}
// The luminance formats can be sampled either in their natural format, or to the intermediate
// composite format used for composition. Direct sampling is always for final output, so the two
// 8-bit formats also provide a gamma option.
fragment float4 sampleLuminance1(SourceInterpolator vert [[stage_in]], texture2d<ushort> texture [[texture(0)]], constant Uniforms &uniforms [[buffer(0)]]) {
const float luminance = clamp(float(texture.sample(standardSampler, vert.textureCoordinates).r), 0.0f, 1.0f) * uniforms.outputMultiplier;
return float4(float3(luminance), uniforms.outputAlpha);
}
fragment float4 compositeSampleLuminance1(SourceInterpolator vert [[stage_in]], texture2d<ushort> texture [[texture(0)]]) {
return composite(texture.sample(standardSampler, vert.textureCoordinates).r, quadrature(vert.colourPhase), vert.colourAmplitude);
}
fragment float4 sampleLuminance8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]], constant Uniforms &uniforms [[buffer(0)]]) {
return float4(texture.sample(standardSampler, vert.textureCoordinates).rrr * uniforms.outputMultiplier, uniforms.outputAlpha);
}
fragment float4 compositeSampleLuminance8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
return composite(texture.sample(standardSampler, vert.textureCoordinates).r, quadrature(vert.colourPhase), vert.colourAmplitude);
}
fragment float4 compositeSamplePhaseLinkedLuminance8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
const int offset = int(vert.unitColourPhase * 4.0f) & 3;
const float snappedColourPhase = float(offset) * (0.5f * 3.141592654f); // TODO: plus machine-supplied offset.
auto sample = texture.sample(standardSampler, vert.textureCoordinates);
return composite(sample[offset], quadrature(snappedColourPhase), vert.colourAmplitude);
}
// The luminance/phase format can produce either composite or S-Video.
/// @returns A 2d vector comprised where .x = luminance; .y = chroma.
float2 convertLuminance8Phase8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
const auto luminancePhase = texture.sample(standardSampler, vert.textureCoordinates).rg;
const float phaseOffset = 3.141592654 * 4.0 * luminancePhase.g;
const float rawChroma = step(luminancePhase.g, 0.75) * cos(vert.colourPhase + phaseOffset);
return float2(luminancePhase.r, rawChroma);
}
fragment float4 sampleLuminance8Phase8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
const float2 luminanceChroma = convertLuminance8Phase8(vert, texture);
const float2 qam = quadrature(vert.colourPhase) * 0.5f;
return float4(luminanceChroma.r,
float2(0.5f) + luminanceChroma.g*qam,
1.0);
}
fragment float4 compositeSampleLuminance8Phase8(SourceInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
const float2 luminanceChroma = convertLuminance8Phase8(vert, texture);
const float level = mix(luminanceChroma.r, luminanceChroma.g, vert.colourAmplitude);
return composite(level, quadrature(vert.colourPhase), vert.colourAmplitude);
}
// All the RGB formats can produce RGB, composite or S-Video.
//
// Note on the below: in Metal you may not call a fragment function (so e.g. svideoSampleX can't just cann sampleX).
// Also I can find no functioning way to offer a templated fragment function. So I don't currently know how
// I could avoid the macro mess below.
// TODO: is the calling convention here causing `vert` and `texture` to be copied?
float3 convertRed8Green8Blue8(SourceInterpolator vert, texture2d<float> texture) {
return float3(texture.sample(standardSampler, vert.textureCoordinates));
}
float3 convertRed4Green4Blue4(SourceInterpolator vert, texture2d<ushort> texture) {
const auto sample = texture.sample(standardSampler, vert.textureCoordinates).rg;
return float3(sample.r&15, (sample.g >> 4)&15, sample.g&15);
}
float3 convertRed2Green2Blue2(SourceInterpolator vert, texture2d<ushort> texture) {
const auto sample = texture.sample(standardSampler, vert.textureCoordinates).r;
return float3((sample >> 4)&3, (sample >> 2)&3, sample&3);
}
float3 convertRed1Green1Blue1(SourceInterpolator vert, texture2d<ushort> texture) {
const auto sample = texture.sample(standardSampler, vert.textureCoordinates).r;
return float3(sample&4, sample&2, sample&1);
}
// TODO: don't hard code the 0.64 in sample##name.
#define DeclareShaders(name, pixelType) \
fragment float4 sample##name(SourceInterpolator vert [[stage_in]], texture2d<pixelType> texture [[texture(0)]]) { \
return float4(convert##name(vert, texture), 0.64); \
} \
\
fragment float4 svideoSample##name(SourceInterpolator vert [[stage_in]], texture2d<pixelType> texture [[texture(0)]], constant Uniforms &uniforms [[buffer(0)]]) { \
const auto colour = float3x3(uniforms.fromRGB) * clamp(convert##name(vert, texture), float(0.0f), float(1.0f)); \
const float2 qam = quadrature(vert.colourPhase); \
const float chroma = dot(colour.gb, qam); \
return float4( \
colour.r, \
float2(0.5f) + chroma*qam*0.5f, \
1.0f \
); \
} \
\
fragment float4 compositeSample##name(SourceInterpolator vert [[stage_in]], texture2d<pixelType> texture [[texture(0)]], constant Uniforms &uniforms [[buffer(0)]]) { \
const auto colour = float3x3(uniforms.fromRGB) * clamp(convert##name(vert, texture), float3(0.0f), float3(1.0f)); \
const float2 colourSubcarrier = quadrature(vert.colourPhase); \
const float level = mix(colour.r, dot(colour.gb, colourSubcarrier), vert.colourAmplitude); \
return composite(level, colourSubcarrier, vert.colourAmplitude); \
}
DeclareShaders(Red8Green8Blue8, float)
DeclareShaders(Red4Green4Blue4, ushort)
DeclareShaders(Red2Green2Blue2, ushort)
DeclareShaders(Red1Green1Blue1, ushort)
fragment float4 copyFragment(CopyInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
return texture.sample(standardSampler, vert.textureCoordinates);
}
fragment float4 interpolateFragment(CopyInterpolator vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
return texture.sample(linearSampler, vert.textureCoordinates);
}
fragment float4 clearFragment() {
return float4(0.0, 0.0, 0.0, 0.64);
}
// MARK: - Compute kernels
/// Given input pixels of the form (luminance, 0.5 + 0.5*chrominance*cos(phase), 0.5 + 0.5*chrominance*sin(phase)), applies a lowpass
/// filter to the two chrominance parts, then uses the toRGB matrix to convert to RGB and stores.
template <bool applyGamma> void filterChromaKernel( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
constexpr half4 moveToZero(0.0f, 0.5f, 0.5f, 0.0f);
const half4 rawSamples[] = {
inTexture.read(gid + uint2(0, offset)) - moveToZero,
inTexture.read(gid + uint2(1, offset)) - moveToZero,
inTexture.read(gid + uint2(2, offset)) - moveToZero,
inTexture.read(gid + uint2(3, offset)) - moveToZero,
inTexture.read(gid + uint2(4, offset)) - moveToZero,
inTexture.read(gid + uint2(5, offset)) - moveToZero,
inTexture.read(gid + uint2(6, offset)) - moveToZero,
inTexture.read(gid + uint2(7, offset)) - moveToZero,
inTexture.read(gid + uint2(8, offset)) - moveToZero,
inTexture.read(gid + uint2(9, offset)) - moveToZero,
inTexture.read(gid + uint2(10, offset)) - moveToZero,
inTexture.read(gid + uint2(11, offset)) - moveToZero,
inTexture.read(gid + uint2(12, offset)) - moveToZero,
inTexture.read(gid + uint2(13, offset)) - moveToZero,
inTexture.read(gid + uint2(14, offset)) - moveToZero,
};
#define Sample(x, y) uniforms.chromaKernel[y] * rawSamples[x].rgb
const half3 colour =
Sample(0, 0) + Sample(1, 1) + Sample(2, 2) + Sample(3, 3) + Sample(4, 4) + Sample(5, 5) + Sample(6, 6) +
Sample(7, 7) +
Sample(8, 6) + Sample(9, 5) + Sample(10, 4) + Sample(11, 3) + Sample(12, 2) + Sample(13, 1) + Sample(14, 0);
#undef Sample
const half4 output = half4(uniforms.toRGB * colour * uniforms.outputMultiplier, uniforms.outputAlpha);
if(applyGamma) {
outTexture.write(pow(output, uniforms.outputGamma), gid + uint2(7, offset));
} else {
outTexture.write(output, gid + uint2(7, offset));
}
}
kernel void filterChromaKernelNoGamma( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
filterChromaKernel<false>(inTexture, outTexture, gid, uniforms, offset);
}
kernel void filterChromaKernelWithGamma( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
filterChromaKernel<true>(inTexture, outTexture, gid, uniforms, offset);
}
void setSeparatedLumaChroma(half luminance, half4 centreSample, texture2d<half, access::write> outTexture, uint2 gid, int offset) {
// The mix/steps below ensures that the absence of a colour burst leads the colour subcarrier to be discarded.
const half isColour = step(half(0.01f), centreSample.a);
const half chroma = (centreSample.r - luminance) / mix(half(1.0f), centreSample.a, isColour);
outTexture.write(half4(
luminance / mix(half(1.0f), (half(1.0f) - centreSample.a), isColour),
isColour * (centreSample.gb - half2(0.5f)) * chroma + half2(0.5f),
1.0f
),
gid + uint2(7, offset));
}
/// Given input pixels of the form:
///
/// (composite sample, cos(phase), sin(phase), colour amplitude), applies a lowpass
///
/// Filters to separate luminance, subtracts that and scales and maps the remaining chrominance in order to output
/// pixels in the form:
///
/// (luminance, 0.5 + 0.5*chrominance*cos(phase), 0.5 + 0.5*chrominance*sin(phase))
///
/// i.e. the input form for the filterChromaKernel, above].
kernel void separateLumaKernel15( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
const half4 centreSample = inTexture.read(gid + uint2(7, offset));
const half rawSamples[] = {
inTexture.read(gid + uint2(0, offset)).r, inTexture.read(gid + uint2(1, offset)).r,
inTexture.read(gid + uint2(2, offset)).r, inTexture.read(gid + uint2(3, offset)).r,
inTexture.read(gid + uint2(4, offset)).r, inTexture.read(gid + uint2(5, offset)).r,
inTexture.read(gid + uint2(6, offset)).r,
centreSample.r,
inTexture.read(gid + uint2(8, offset)).r,
inTexture.read(gid + uint2(9, offset)).r, inTexture.read(gid + uint2(10, offset)).r,
inTexture.read(gid + uint2(11, offset)).r, inTexture.read(gid + uint2(12, offset)).r,
inTexture.read(gid + uint2(13, offset)).r, inTexture.read(gid + uint2(14, offset)).r,
};
#define Sample(x, y) uniforms.lumaKernel[y] * rawSamples[x]
const half luminance =
Sample(0, 0) + Sample(1, 1) + Sample(2, 2) + Sample(3, 3) + Sample(4, 4) + Sample(5, 5) + Sample(6, 6) +
Sample(7, 7) +
Sample(8, 6) + Sample(9, 5) + Sample(10, 4) + Sample(11, 3) + Sample(12, 2) + Sample(13, 1) + Sample(14, 0);
#undef Sample
return setSeparatedLumaChroma(luminance, centreSample, outTexture, gid, offset);
}
kernel void separateLumaKernel9( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
const half4 centreSample = inTexture.read(gid + uint2(7, offset));
const half rawSamples[] = {
inTexture.read(gid + uint2(3, offset)).r, inTexture.read(gid + uint2(4, offset)).r,
inTexture.read(gid + uint2(5, offset)).r, inTexture.read(gid + uint2(6, offset)).r,
centreSample.r,
inTexture.read(gid + uint2(8, offset)).r, inTexture.read(gid + uint2(9, offset)).r,
inTexture.read(gid + uint2(10, offset)).r, inTexture.read(gid + uint2(11, offset)).r
};
#define Sample(x, y) uniforms.lumaKernel[y] * rawSamples[x]
const half luminance =
Sample(0, 3) + Sample(1, 4) + Sample(2, 5) + Sample(3, 6) +
Sample(4, 7) +
Sample(5, 6) + Sample(6, 5) + Sample(7, 4) + Sample(8, 3);
#undef Sample
return setSeparatedLumaChroma(luminance, centreSample, outTexture, gid, offset);
}
kernel void separateLumaKernel7( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
const half4 centreSample = inTexture.read(gid + uint2(7, offset));
const half rawSamples[] = {
inTexture.read(gid + uint2(4, offset)).r,
inTexture.read(gid + uint2(5, offset)).r, inTexture.read(gid + uint2(6, offset)).r,
centreSample.r,
inTexture.read(gid + uint2(8, offset)).r, inTexture.read(gid + uint2(9, offset)).r,
inTexture.read(gid + uint2(10, offset)).r
};
#define Sample(x, y) uniforms.lumaKernel[y] * rawSamples[x]
const half luminance =
Sample(0, 4) + Sample(1, 5) + Sample(2, 6) +
Sample(3, 7) +
Sample(4, 6) + Sample(5, 5) + Sample(6, 4);
#undef Sample
return setSeparatedLumaChroma(luminance, centreSample, outTexture, gid, offset);
}
kernel void separateLumaKernel5( texture2d<half, access::read> inTexture [[texture(0)]],
texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]],
constant Uniforms &uniforms [[buffer(0)]],
constant int &offset [[buffer(1)]]) {
const half4 centreSample = inTexture.read(gid + uint2(7, offset));
const half rawSamples[] = {
inTexture.read(gid + uint2(5, offset)).r, inTexture.read(gid + uint2(6, offset)).r,
centreSample.r,
inTexture.read(gid + uint2(8, offset)).r, inTexture.read(gid + uint2(9, offset)).r,
};
#define Sample(x, y) uniforms.lumaKernel[y] * rawSamples[x]
const half luminance =
Sample(0, 5) + Sample(1, 6) +
Sample(2, 7) +
Sample(3, 6) + Sample(4, 5);
#undef Sample
return setSeparatedLumaChroma(luminance, centreSample, outTexture, gid, offset);
}
kernel void clearKernel( texture2d<half, access::write> outTexture [[texture(1)]],
uint2 gid [[thread_position_in_grid]]) {
outTexture.write(half4(0.0f, 0.0f, 0.0f, 1.0f), gid);
}