uniform float4x4 u_Projection;
uniform float4x4 u_View;
uniform float4x4 u_Model;
uniform float4 u_Color;
uniform bool u_HasTexture;
uniform Sampler2D u_Texture;

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

struct Fragment {
  float4 color;
};

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

float4 someFunction(float4 color) {
  return color * float4(0.5, 0.5, 0.5, 1.0);
}

[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(u_Model, mul(u_View, u_Projection))
  );

  return output;
}

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