//
//  Shaders.metal
//  LenzCameraNativeModuleForRN
//
//  Created by 王昭威 on 2023/1/26.
//

#include "LenzCommon.h"
#include <metal_stdlib>

using namespace metal;

typedef struct{
//    float3 position [[attribute]];
}VertextIn;

typedef struct{
    float4 position [[position]];
    float2 uv;
}VertextOut;


vertex VertextOut vert_main(uint vertId [[vertex_id]]){
    float4x4 vertices = float4x4(
                                 float4( -1.0, -1.0, 0.0, 1.0 ),
                                 float4(  1.0, -1.0, 0.0, 1.0 ),
                                 float4( -1.0,  1.0, 0.0, 1.0 ),
                                 float4(  1.0,  1.0, 0.0, 1.0 )
                                 );
    
    float4x2 uvs = float4x2(
                            float2( 0.0, 1.0 ),
                            float2( 1.0, 1.0 ),
                            float2( 0.0, 0.0 ),
                            float2( 1.0, 0.0 )
                            );
    
    return VertextOut{
        .position = vertices[vertId],
        .uv = uvs[vertId],
    };
}

fragment half4 frag_main(VertextOut in [[stage_in]], texture2d<float> texture [[texture(CameraCapturedTexture)]]){
    sampler s = sampler(address::clamp_to_edge,
                        filter::linear);
    if(is_null_texture(texture)){
        return half4(0, 0, 0, 1);
    }
    return half4(texture.sample(s, in.uv));
}