#version 120
//
// vertexblend.vert
//
attribute vec3 position;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;

// ボーンのデータ
const int MAXBONES = 8;
uniform int numberOfBones;
uniform vec4 boneBottom[MAXBONES], boneTop[MAXBONES];
uniform mat4 blendMatrix[MAXBONES];

// 重みの算出に用いる指数
const float exponent = -16.0;

void main()
{
  vec4 p = modelViewMatrix * vec4(position, 1.0);
  vec4 q = vec4(0.0);
  for (int i = 0; i < numberOfBones; ++i) {
    vec4 v1 = boneTop[i] - boneBottom[i];
    vec4 v2 = p - boneBottom[i];
    float l = dot(v1, v1);
    if (l > 0.0) v2 -= v1 * clamp(dot(v1, v2) / l, 0.0, 1.0);
    q += blendMatrix[i] * p * pow(length(v2) + 1.0, exponent);
  }
  gl_Position = projectionMatrix * q;
}