// 应用顶点光照 Blinn-Phone光照模型;
public static void ApplyVertexLightings(List <IPosLight> lights,
Vector3 eyeWorldPos, Vector3 ptWorldPos, Vector3 ptWorldNorm, ref Vertex2D pt)
{
if (!enableLightings)
{
return;
}
if (null == lights)
{
return;
}
int lightCount = lights.Count;
for (int i = 0; i < lightCount; ++i)
{
IPosLight light = lights[i];
if (null == light || !light.Enable)
{
continue;
}
ApplyLighting(light, eyeWorldPos, ptWorldPos, ptWorldNorm, ref pt);
}
// 环境光;
AmbientLight ambientLight = AmbientLight.Instance;
if (null != ambientLight && ambientLight.Enable)
{
pt.diffuse = ambientLight.LightColor + pt.diffuse;
}
}
private static void ApplyLighting(IPosLight light, Vector3 eyeWorldPos, Vector3 worldPos, Vector3 worldNorm, ref Vertex2D pt)
{
var lightDir = Vector3.Normalize(light.Position - worldPos);
// 反射角;
float diffuse = Math.Max(0, Vector3.Dot(worldNorm, lightDir));
diffuse = diffuse < 0f ? 0f : diffuse;
// apply diffuse;
pt.diffuse += Color.Multiply(light.LightColor, diffuse);
// apply specular;
Vector3 inViewDir = Vector3.Normalize(eyeWorldPos - worldPos);
Vector3 helfDir = Vector3.Normalize(inViewDir + lightDir);
float specular = 0;
if (diffuse != 0)
{
//防止出现光源在物体背面产生高光的情况;
float sp = MathUtil.Clamp(Math.Max(0, Vector3.Dot(helfDir, worldNorm)));
specular = (float)System.Math.Pow(sp, 4);
}
pt.specular += Color.Multiply(light.LightColor, specular);
}
