uniform float4x4 projection;
uniform float4x4 view;
uniform float4x4 model;
uniform float4 color;
uniform bool hasTexture;
uniform Sampler2D texture;

struct AssembledVertex {
  float3 position : POSITION;
  float2 texcoord : TEXCOORD;
};

struct Fragment {
  float4 color;
};

struct VertexStageOutput {
  float2 uv : UV;
  float4 sv_position : SV_Position;
};

[shader("vertex")]
VertexStageOutput vertexMain(
  AssembledVertex assembledVertex
) {
  VertexStageOutput output;

  float3 position = assembledVertex.position;

  output.uv = assembledVertex.texcoord;

  output.sv_position = mul(
    float4(position, 1.0),
    mul(model, mul(view, projection))
  );

  return output;
}

[shader("fragment")]
Fragment fragmentMain(
  float2 uv: UV
) : SV_Target {
  Fragment output;
  
  if (hasTexture) {
    output.color = texture.Sample(uv) * color;
  } else {
    output.color = color;
  }
  
  return output;
}