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#include <metal_common>
#include <metal_texture>
#include <metal_matrix>
using namespace metal;
// These should mirror the definitions in SDL_render_metal.m
#define TONEMAP_NONE 0
#define TONEMAP_LINEAR 1
#define TONEMAP_CHROME 2
#define TEXTURETYPE_NONE 0
#define TEXTURETYPE_RGB 1
#define TEXTURETYPE_NV12 2
#define TEXTURETYPE_NV21 3
#define TEXTURETYPE_YUV 4
#define INPUTTYPE_UNSPECIFIED 0
#define INPUTTYPE_SRGB 1
#define INPUTTYPE_SCRGB 2
#define INPUTTYPE_HDR10 3
struct ShaderConstants
{
float scRGB_output;
float texture_type;
float input_type;
float color_scale;
float tonemap_method;
float tonemap_factor1;
float tonemap_factor2;
float sdr_white_point;
};
struct YUVDecode
{
float3 offset;
float3x3 matrix;
};
float sRGBtoLinear(float v)
{
if (v <= 0.04045) {
v = (v / 12.92);
} else {
v = pow(abs(v + 0.055) / 1.055, 2.4);
}
return v;
}
float sRGBfromLinear(float v)
{
if (v <= 0.0031308) {
v = (v * 12.92);
} else {
v = (pow(abs(v), 1.0 / 2.4) * 1.055 - 0.055);
}
return v;
}
float3 PQtoLinear(float3 v, float sdr_white_point)
{
const float c1 = 0.8359375;
const float c2 = 18.8515625;
const float c3 = 18.6875;
const float oo_m1 = 1.0 / 0.1593017578125;
const float oo_m2 = 1.0 / 78.84375;
float3 num = max(pow(abs(v), oo_m2) - c1, 0.0);
float3 den = c2 - c3 * pow(abs(v), oo_m2);
return (10000.0 * pow(abs(num / den), oo_m1) / sdr_white_point);
}
float3 ApplyTonemap(float3 v, float input_type, float tonemap_method, float tonemap_factor1, float tonemap_factor2)
{
const float3x3 mat709to2020 = {
{ 0.627404, 0.329283, 0.043313 },
{ 0.069097, 0.919541, 0.011362 },
{ 0.016391, 0.088013, 0.895595 }
};
const float3x3 mat2020to709 = {
{ 1.660496, -0.587656, -0.072840 },
{ -0.124547, 1.132895, -0.008348 },
{ -0.018154, -0.100597, 1.118751 }
};
if (tonemap_method == TONEMAP_LINEAR) {
v *= tonemap_factor1;
} else if (tonemap_method == TONEMAP_CHROME) {
if (input_type == INPUTTYPE_SCRGB) {
// Convert to BT.2020 colorspace for tone mapping
v = v * mat709to2020;
}
float vmax = max(v.r, max(v.g, v.b));
if (vmax > 0.0) {
float scale = (1.0 + tonemap_factor1 * vmax) / (1.0 + tonemap_factor2 * vmax);
v *= scale;
}
if (input_type == INPUTTYPE_SCRGB) {
// Convert to BT.709 colorspace after tone mapping
v = v * mat2020to709;
}
}
return v;
}
float4 GetOutputColorSimple(float4 rgba, float color_scale)
{
float4 output;
output.rgb = rgba.rgb * color_scale;
output.a = rgba.a;
return output;
}
float3 GetOutputColorFromSRGB(float3 rgb, float scRGB_output, float color_scale)
{
float3 output;
if (scRGB_output) {
rgb.r = sRGBtoLinear(rgb.r);
rgb.g = sRGBtoLinear(rgb.g);
rgb.b = sRGBtoLinear(rgb.b);
}
output = rgb * color_scale;
return output;
}
float3 GetOutputColorFromLinear(float3 rgb, float scRGB_output, float color_scale)
{
float3 output;
output = rgb * color_scale;
if (!scRGB_output) {
output.r = sRGBfromLinear(output.r);
output.g = sRGBfromLinear(output.g);
output.b = sRGBfromLinear(output.b);
output = clamp(output, 0.0, 1.0);
}
return output;
}
float4 GetOutputColor(float4 rgba, constant ShaderConstants &c)
{
const float3x3 mat2020to709 = {
{ 1.660496, -0.587656, -0.072840 },
{ -0.124547, 1.132895, -0.008348 },
{ -0.018154, -0.100597, 1.118751 }
};
float4 output;
if (c.input_type == INPUTTYPE_HDR10) {
rgba.rgb = PQtoLinear(rgba.rgb, c.sdr_white_point);
}
if (c.tonemap_method != TONEMAP_NONE) {
rgba.rgb = ApplyTonemap(rgba.rgb, c.input_type, c.tonemap_method, c.tonemap_factor1, c.tonemap_factor2);
}
if (c.input_type == INPUTTYPE_SRGB) {
if (c.texture_type == TEXTURETYPE_RGB) {
// The sampler has already converted to linear if necessary
output.rgb = rgba.rgb * c.color_scale;
} else {
output.rgb = GetOutputColorFromSRGB(rgba.rgb, c.scRGB_output, c.color_scale);
}
} else if (c.input_type == INPUTTYPE_SCRGB) {
output.rgb = GetOutputColorFromLinear(rgba.rgb, c.scRGB_output, c.color_scale);
} else if (c.input_type == INPUTTYPE_HDR10) {
rgba.rgb = rgba.rgb * mat2020to709;
output.rgb = GetOutputColorFromLinear(rgba.rgb, c.scRGB_output, c.color_scale);
} else {
// Unexpected input type, use magenta error color
output.rgb = float3(1.0, 0.0, 1.0);
}
output.a = rgba.a;
return output;
}
struct SolidVertexInput
{
float2 position [[attribute(0)]];
float4 color [[attribute(1)]];
};
struct SolidVertexOutput
{
float4 position [[position]];
float4 color;
float pointSize [[point_size]];
};
vertex SolidVertexOutput SDL_Solid_vertex(SolidVertexInput in [[stage_in]],
constant float4x4 &projection [[buffer(2)]],
constant float4x4 &transform [[buffer(3)]])
{
SolidVertexOutput v;
v.position = (projection * transform) * float4(in.position, 0.0f, 1.0f);
v.color = in.color;
v.pointSize = 1.0f;
return v;
}
fragment float4 SDL_Solid_fragment(SolidVertexInput in [[stage_in]],
constant ShaderConstants &c [[buffer(0)]])
{
return GetOutputColorSimple(1.0, c.color_scale) * in.color;
}
struct CopyVertexInput
{
float2 position [[attribute(0)]];
float4 color [[attribute(1)]];
float2 texcoord [[attribute(2)]];
};
struct CopyVertexOutput
{
float4 position [[position]];
float4 color;
float2 texcoord;
};
vertex CopyVertexOutput SDL_Copy_vertex(CopyVertexInput in [[stage_in]],
constant float4x4 &projection [[buffer(2)]],
constant float4x4 &transform [[buffer(3)]])
{
CopyVertexOutput v;
v.position = (projection * transform) * float4(in.position, 0.0f, 1.0f);
v.color = in.color;
v.texcoord = in.texcoord;
return v;
}
fragment float4 SDL_Copy_fragment(CopyVertexOutput vert [[stage_in]],
constant ShaderConstants &c [[buffer(0)]],
texture2d<float> tex [[texture(0)]],
sampler s [[sampler(0)]])
{
float4 rgba = tex.sample(s, vert.texcoord);
return GetOutputColor(rgba, c) * vert.color;
}
fragment float4 SDL_YUV_fragment(CopyVertexOutput vert [[stage_in]],
constant ShaderConstants &c [[buffer(0)]],
constant YUVDecode &decode [[buffer(1)]],
texture2d<float> texY [[texture(0)]],
texture2d_array<float> texUV [[texture(1)]],
sampler s [[sampler(0)]])
{
float3 yuv;
yuv.x = texY.sample(s, vert.texcoord).r;
yuv.y = texUV.sample(s, vert.texcoord, 0).r;
yuv.z = texUV.sample(s, vert.texcoord, 1).r;
float4 rgba;
rgba.rgb = (yuv + decode.offset) * decode.matrix;
rgba.a = 1.0;
return GetOutputColor(rgba, c) * vert.color;
}
fragment float4 SDL_NV12_fragment(CopyVertexOutput vert [[stage_in]],
constant ShaderConstants &c [[buffer(0)]],
constant YUVDecode &decode [[buffer(1)]],
texture2d<float> texY [[texture(0)]],
texture2d<float> texUV [[texture(1)]],
sampler s [[sampler(0)]])
{
float4 rgba;
if (c.texture_type == TEXTURETYPE_NV12) {
float3 yuv;
yuv.x = texY.sample(s, vert.texcoord).r;
yuv.yz = texUV.sample(s, vert.texcoord).rg;
rgba.rgb = (yuv + decode.offset) * decode.matrix;
} else if (c.texture_type == TEXTURETYPE_NV21) {
float3 yuv;
yuv.x = texY.sample(s, vert.texcoord).r;
yuv.yz = texUV.sample(s, vert.texcoord).gr;
rgba.rgb = (yuv + decode.offset) * decode.matrix;
} else {
// Unexpected texture type, use magenta error color
rgba.rgb = float3(1.0, 0.0, 1.0);
}
rgba.a = 1.0;
return GetOutputColor(rgba, c) * vert.color;
}
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