在渲染一个具体的物体之前，Ogre会查找与该物体相关的光源，根据光源的范围，内角和外角(如果是聚光灯)等参数进行计算，如果物体受到光源的影响，则将此光源的参数传入着色器进行光照计算。如果没有找到一个光源，那么传入一个空白的光源参数给着色器。

查找物体相关的光源代码如下：

bool Light::isInLightRange(const Ogre::Sphere& container) const
	{
		bool isIntersect = true;
		//directional light always intersects (check only spotlight and point)
		if (mLightType != LT_DIRECTIONAL)
		{
			//Check that the sphere is within the sphere of the light
			isIntersect = container.intersects(Sphere(mDerivedPosition, mRange));
			//If this is a spotlight, check that the sphere is within the cone of the spot light
			if ((isIntersect) && (mLightType == LT_SPOTLIGHT))
			{
				//check first check of the sphere surrounds the position of the light
				//(this covers the case where the center of the sphere is behind the position of the light
				// something which is not covered in the next test).
				isIntersect = container.intersects(mDerivedPosition);
				//if not test cones
				if (!isIntersect)
				{
					//Calculate the cone that exists between the sphere and the center position of the light
					Ogre::Vector3 lightSphereConeDirection = container.getCenter() - mDerivedPosition;
					Ogre::Radian halfLightSphereConeAngle = Math::ASin(container.getRadius() / lightSphereConeDirection.length());

					//Check that the light cone and the light-position-to-sphere cone intersect)
					Radian angleBetweenConeDirections = lightSphereConeDirection.angleBetween(mDerivedDirection);
					isIntersect = angleBetweenConeDirections <=  halfLightSphereConeAngle + mSpotOuter * 0.5;
				}
			}
		}
		return isIntersect;
	}

空白光源的定义如下：

    Light mBlankLight;

    Light::Light()
		: mLightType(LT_POINT),
          mPosition(Vector3::ZERO),
          mDiffuse(ColourValue::White),
          mSpecular(ColourValue::Black),
          mDirection(Vector3::UNIT_Z),
		  mSpotOuter(Degree(40.0f)),
          mSpotInner(Degree(30.0f)),
          mSpotFalloff(1.0f),
          mSpotNearClip(0.0f),
		  mRange(100000),
		  mAttenuationConst(1.0f),
		  mAttenuationLinear(0.0f),
          mAttenuationQuad(0.0f),
		  mPowerScale(1.0f),
		  mIndexInFrame(0),
		  mOwnShadowFarDist(false),
		  mShadowFarDist(0),
		  mShadowFarDistSquared(0),
		  mShadowNearClipDist(-1),
		  mShadowFarClipDist(-1),
          mDerivedPosition(Vector3::ZERO),
          mDerivedDirection(Vector3::UNIT_Z),
		  mDerivedCamRelativePosition(Vector3::ZERO),
		  mDerivedCamRelativeDirty(false),
		  mCameraToBeRelativeTo(0),
          mDerivedTransformDirty(false),
		  mCustomShadowCameraSetup()
    {
		//mMinPixelSize should always be zero for lights otherwise lights will disapear
    	mMinPixelSize = 0;
    }


    mBlankLight.setDiffuseColour(ColourValue::Black);
    mBlankLight.setSpecularColour(ColourValue::Black);
    mBlankLight.setAttenuation(0,1,0,0);

以下因为光源参数设置不当，导致使用了空板光源参数，而产生错误的渲染效果

 注意：其他参数不正确是因为hsls中没有使用这些变量，所以ogre没有传入这些参数的值，导致这些对应的变量没有得到初始化！