/*
 * Copyright 2009, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// The 4x4 world view projection matrix.
float4x4 worldViewProjection : WorldViewProjection;
float4x4 worldInverseTranspose : WorldInverseTranspose;
float4x4 world : World;

float4 ambientIntensity;
float4 lightIntensity;
float4 ambient;
float4 diffuse;
float3 lightWorldPos;

// input parameters for our vertex shader
struct VertexShaderInput {
  float4 position : POSITION;  // Position vector of vertex
  float4 normal : NORMAL;
};

// input parameters for our pixel shader
struct PixelShaderInput {
  float4 position : POSITION;
  float3 normal : TEXCOORD0;
  float3 worldPosition : TEXCOORD1;
};

/**
 * Our vertex shader.
 */
PixelShaderInput vertexShaderFunction(VertexShaderInput input) {
  PixelShaderInput output;

  // Transform position into clip space.
  output.position = mul(input.position, worldViewProjection);

  // Transform normal into world space, where we can do lighting
  // calculations even if the world transform contains scaling.
  output.normal = mul(input.normal, worldInverseTranspose).xyz;

  // Calculate surface position in world space.
  output.worldPosition = mul(input.position, world).xyz;

  return output;
}

/**
 * Our pixel shader.
 */
float4 pixelShaderFunction(PixelShaderInput input): COLOR {
  float3 surfaceToLight = normalize(lightWorldPos - input.worldPosition);

  float3 worldNormal = normalize(input.normal);

  // Apply diffuse lighting in world space in case the world transform
  // contains scaling.
  float4 directionalIntensity = lightIntensity *
      saturate(dot(worldNormal, surfaceToLight));
  float4 outColor = ambientIntensity * ambient + directionalIntensity * diffuse;
  return float4(outColor.rgb, diffuse.a);
}

// Here we tell our effect file *which* functions are
// our vertex and pixel shaders.

// #o3d VertexShaderEntryPoint vertexShaderFunction
// #o3d PixelShaderEntryPoint pixelShaderFunction
// #o3d MatrixLoadOrder RowMajor