hlsl的 投影和view矩阵

hlsl的 投影和view矩阵

float4x4 LookAtMatrix(float3 eyePosition, float3 lookAt, float3 up)

{

    float3 zaxis = normalize(lookAt - eyePosition);

    float3 yaxis = normalize(up);

    float3 xaxis = normalize(cross(yaxis, zaxis));

    yaxis = normalize(cross(zaxis, xaxis));

    

    float4x4 result = float4x4(xaxis.x, yaxis.x, zaxis.x, 0.0,

                               xaxis.y, yaxis.y, zaxis.y, 0.0,

                               xaxis.z, yaxis.z, zaxis.z, 0.0,

     -dot(xaxis, eyePosition), -dot(yaxis, eyePosition), -dot(zaxis, eyePosition), 1.0);

                   

    return result;

}

#define MATH_PI_DIV_180  0.0174532925

float4x4 DxPorjMatrix(float fov_y, float aspect, float zNear, float zFar)

{

    // Left Hand

    float f_n = 1.0f / (zFar - zNear);

    float yScale = 1.0 / tan(MATH_PI_DIV_180 * (fov_y) * 0.5f);

    float xScale = yScale / aspect;

    float4x4 result = float4x4(xScale, 0.0, 0.0, 0.0,

                               0.0, yScale, 0.0, 0.0,

                               0.0, 0.0, zFar*f_n, 1.0,

                               0.0, 0.0, -zNear * zFar * f_n, 1.0);

    return result;

}

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