reference/shaders-msl/vert/functions.vert

#pragma clang diagnostic ignored "-Wmissing-prototypes"

#include <metal_stdlib>
#include <simd/simd.h>

using namespace metal;

struct UBO
{
    float4x4 uMVP;
    float3 rotDeg;
    float3 rotRad;
    int2 bits;
};

struct main0_out
{
    float3 vNormal [[user(locn0)]];
    float3 vRotDeg [[user(locn1)]];
    float3 vRotRad [[user(locn2)]];
    int2 vLSB [[user(locn3)]];
    int2 vMSB [[user(locn4)]];
    float4 gl_Position [[position]];
};

struct main0_in
{
    float4 aVertex [[attribute(0)]];
    float3 aNormal [[attribute(1)]];
};

// Implementation of the GLSL radians() function
template<typename T>
T radians(T d)
{
    return d * T(0.01745329251);
}

// Implementation of the GLSL degrees() function
template<typename T>
T degrees(T r)
{
    return r * T(57.2957795131);
}

// Implementation of the GLSL findLSB() function
template<typename T>
T findLSB(T x)
{
    return select(ctz(x), T(-1), x == T(0));
}

// Implementation of the signed GLSL findMSB() function
template<typename T>
T findSMSB(T x)
{
    T v = select(x, T(-1) - x, x < T(0));
    return select(clz(T(0)) - (clz(v) + T(1)), T(-1), v == T(0));
}

// Returns the determinant of a 2x2 matrix.
inline float spvDet2x2(float a1, float a2, float b1, float b2)
{
    return a1 * b2 - b1 * a2;
}

// Returns the determinant of a 3x3 matrix.
inline float spvDet3x3(float a1, float a2, float a3, float b1, float b2, float b3, float c1, float c2, float c3)
{
    return a1 * spvDet2x2(b2, b3, c2, c3) - b1 * spvDet2x2(a2, a3, c2, c3) + c1 * spvDet2x2(a2, a3, b2, b3);
}

// Returns the inverse of a matrix, by using the algorithm of calculating the classical
// adjoint and dividing by the determinant. The contents of the matrix are changed.
float4x4 spvInverse4x4(float4x4 m)
{
    float4x4 adj;	// The adjoint matrix (inverse after dividing by determinant)

    // Create the transpose of the cofactors, as the classical adjoint of the matrix.
    adj[0][0] =  spvDet3x3(m[1][1], m[1][2], m[1][3], m[2][1], m[2][2], m[2][3], m[3][1], m[3][2], m[3][3]);
    adj[0][1] = -spvDet3x3(m[0][1], m[0][2], m[0][3], m[2][1], m[2][2], m[2][3], m[3][1], m[3][2], m[3][3]);
    adj[0][2] =  spvDet3x3(m[0][1], m[0][2], m[0][3], m[1][1], m[1][2], m[1][3], m[3][1], m[3][2], m[3][3]);
    adj[0][3] = -spvDet3x3(m[0][1], m[0][2], m[0][3], m[1][1], m[1][2], m[1][3], m[2][1], m[2][2], m[2][3]);

    adj[1][0] = -spvDet3x3(m[1][0], m[1][2], m[1][3], m[2][0], m[2][2], m[2][3], m[3][0], m[3][2], m[3][3]);
    adj[1][1] =  spvDet3x3(m[0][0], m[0][2], m[0][3], m[2][0], m[2][2], m[2][3], m[3][0], m[3][2], m[3][3]);
    adj[1][2] = -spvDet3x3(m[0][0], m[0][2], m[0][3], m[1][0], m[1][2], m[1][3], m[3][0], m[3][2], m[3][3]);
    adj[1][3] =  spvDet3x3(m[0][0], m[0][2], m[0][3], m[1][0], m[1][2], m[1][3], m[2][0], m[2][2], m[2][3]);

    adj[2][0] =  spvDet3x3(m[1][0], m[1][1], m[1][3], m[2][0], m[2][1], m[2][3], m[3][0], m[3][1], m[3][3]);
    adj[2][1] = -spvDet3x3(m[0][0], m[0][1], m[0][3], m[2][0], m[2][1], m[2][3], m[3][0], m[3][1], m[3][3]);
    adj[2][2] =  spvDet3x3(m[0][0], m[0][1], m[0][3], m[1][0], m[1][1], m[1][3], m[3][0], m[3][1], m[3][3]);
    adj[2][3] = -spvDet3x3(m[0][0], m[0][1], m[0][3], m[1][0], m[1][1], m[1][3], m[2][0], m[2][1], m[2][3]);

    adj[3][0] = -spvDet3x3(m[1][0], m[1][1], m[1][2], m[2][0], m[2][1], m[2][2], m[3][0], m[3][1], m[3][2]);
    adj[3][1] =  spvDet3x3(m[0][0], m[0][1], m[0][2], m[2][0], m[2][1], m[2][2], m[3][0], m[3][1], m[3][2]);
    adj[3][2] = -spvDet3x3(m[0][0], m[0][1], m[0][2], m[1][0], m[1][1], m[1][2], m[3][0], m[3][1], m[3][2]);
    adj[3][3] =  spvDet3x3(m[0][0], m[0][1], m[0][2], m[1][0], m[1][1], m[1][2], m[2][0], m[2][1], m[2][2]);

    // Calculate the determinant as a combination of the cofactors of the first row.
    float det = (adj[0][0] * m[0][0]) + (adj[0][1] * m[1][0]) + (adj[0][2] * m[2][0]) + (adj[0][3] * m[3][0]);

    // Divide the classical adjoint matrix by the determinant.
    // If determinant is zero, matrix is not invertable, so leave it unchanged.
    return (det != 0.0f) ? (adj * (1.0f / det)) : m;
}

vertex main0_out main0(main0_in in [[stage_in]], constant UBO& _18 [[buffer(0)]])
{
    main0_out out = {};
    out.gl_Position = spvInverse4x4(_18.uMVP) * in.aVertex;
    out.vNormal = in.aNormal;
    out.vRotDeg = degrees(_18.rotRad);
    out.vRotRad = radians(_18.rotDeg);
    out.vLSB = findLSB(_18.bits);
    out.vMSB = findSMSB(_18.bits);
    return out;
}