import "includes/structs";

struct Varyings {
    float4 positionCS : SV_Position;
    nointerpolation uint instance;
    float2 texCoord;
}

struct GuiImage {
    float4 tint;
    float2 positionSSPX;
    float2 sizePX;
    float2 uvMin;
    float2 uvMax;
    uint16_t texture;
}

[[vk::binding(0, 0)]] ConstantBuffer<GlobalUniforms> _Global;
[[vk::binding(1, 0)]] StructuredBuffer<GuiImage> _Images;
[[vk::binding(2, 0)]] SamplerState _Sampler;
[[vk::binding(3, 0)]] Texture2D _Textures[];

static const float2 VERTICES[4] = {
    float2(0, 1),
    float2(1, 1),
    float2(0, 0),
    float2(1, 0),
};

[shader("vertex")]
Varyings vertexMain(uint vertexID : SV_VulkanVertexID, uint instanceID : SV_VulkanInstanceID) {
    Varyings out;

    let vertex = VERTICES[vertexID];
    let image = _Images[instanceID];

    let positionSSPX = vertex * image.sizePX + image.positionSSPX;
    let positionCS = float4(mul(_Global.matrixSSPXtoCS, float3(positionSSPX, 1.0)), 0.0, 1.0);

    let texCoord = vertex * (image.uvMax - image.uvMin) + image.uvMin;

    out.positionCS = positionCS;
    out.instance = instanceID;
    out.texCoord = texCoord;
    return out;
}

[shader("fragment")]
float4 fragmentMain(Varyings frag) : SV_Target {
    let image = _Images[frag.instance];
    let texel = _Textures[image.texture].Sample(_Sampler, frag.texCoord);
    return texel * image.tint;
}