precision highp  float;

varying vec3 ModelPos;

uniform float isYUV;  // false: 0, true: 1.0
uniform sampler2D texture_video;

uniform vec3 focal_width_height;

vec2 SampleTex(vec3 pt3d)
{
    return focal_width_height.x / focal_width_height.yz * pt3d.xy / pt3d.z + 0.5;
}

void main()
{
    vec3 color = vec3(0,0,0);
    float shadow = 1.0;
    
    vec2 uv =  SampleTex( normalize(ModelPos) );

    if( isYUV < 0.5 )
    {
        color = texture2D(texture_video, uv).rgb;
    }else{
        const mat4 YUV2RGB = mat4
        (
            1.1643828125, 0, 1.59602734375, -.87078515625,
            1.1643828125, -.39176171875, -.81296875, .52959375,
            1.1643828125, 2.017234375, 0, -1.081390625,
            0, 0, 0, 1
        );    
        
        vec4 result = vec4( 
            texture2D( texture_video, vec2( uv.x,   uv.y * 0.666666 + 0.333333 ) ).x,
            texture2D( texture_video, vec2( uv.x * 0.5,        uv.y * 0.333333 ) ).x, 
            texture2D( texture_video, vec2( 0.5 + uv.x * 0.5,  uv.y * 0.333333 ) ).x,
            1
        ) * YUV2RGB;  

        color = clamp(result.rgb, 0.0, 1.0); 
    }
    if( uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0 )
    {
        color = vec3(0,0,0);
    }
    gl_FragColor = vec4(shadow * color * 1.0, 1.0); 
}