绘制流程。
使用是：
1.创建light
2light到场景。
2.调用render方法。
解析render方法对light处理过程。
this.render = function ( scene, camera, renderTarget, forceClear )
- 会将确定当前需要绘制scene和camera。从而确定当前需要渲染哪些。其中场景决定了哪些灯光需要参与渲染。
- render会调用renderState.setupLights(camera).
- setupLights调用webGLLights.setup(lights, shadows, camera)
- 重点是setup方法
function setup( lights, shadows, camera ) {
var r = 0, g = 0, b = 0;
var directionalLength = 0;
var pointLength = 0;
var spotLength = 0;
var rectAreaLength = 0;
var hemiLength = 0;
var viewMatrix = camera.matrixWorldInverse;
for ( var i = 0, l = lights.length; i < l; i ++ ) {
var light = lights[ i ];
var color = light.color;
var intensity = light.intensity;
var distance = light.distance;
var shadowMap = ( light.shadow && light.shadow.map ) ? light.shadow.map.texture : null;
if ( light.isAmbientLight ) {
r += color.r * intensity;
g += color.g * intensity;
b += color.b * intensity;
} else if ( light.isDirectionalLight ) {
var uniforms = cache.get( light );
uniforms.color.copy( light.color ).multiplyScalar( light.intensity );
uniforms.direction.setFromMatrixPosition( light.matrixWorld );
vector3.setFromMatrixPosition( light.target.matrixWorld );
uniforms.direction.sub( vector3 );
uniforms.direction.transformDirection( viewMatrix );
uniforms.shadow = light.castShadow;
if ( light.castShadow ) {
var shadow = light.shadow;
uniforms.shadowBias = shadow.bias;
uniforms.shadowRadius = shadow.radius;
uniforms.shadowMapSize = shadow.mapSize;
}
state.directionalShadowMap[ directionalLength ] = shadowMap;
state.directionalShadowMatrix[ directionalLength ] = light.shadow.matrix;
state.directional[ directionalLength ] = uniforms;
directionalLength ++;
} else if ( light.isSpotLight ) {
var uniforms = cache.get( light );
uniforms.position.setFromMatrixPosition( light.matrixWorld );
uniforms.position.applyMatrix4( viewMatrix );
uniforms.color.copy( color ).multiplyScalar( intensity );
uniforms.distance = distance;
uniforms.direction.setFromMatrixPosition( light.matrixWorld );
vector3.setFromMatrixPosition( light.target.matrixWorld );
uniforms.direction.sub( vector3 );
uniforms.direction.transformDirection( viewMatrix );
uniforms.coneCos = Math.cos( light.angle );
uniforms.penumbraCos = Math.cos( light.angle * ( 1 - light.penumbra ) );
uniforms.decay = light.decay;
uniforms.shadow = light.castShadow;
if ( light.castShadow ) {
var shadow = light.shadow;
uniforms.shadowBias = shadow.bias;
uniforms.shadowRadius = shadow.radius;
uniforms.shadowMapSize = shadow.mapSize;
}
state.spotShadowMap[ spotLength ] = shadowMap;
state.spotShadowMatrix[ spotLength ] = light.shadow.matrix;
state.spot[ spotLength ] = uniforms;
spotLength ++;
} else if ( light.isRectAreaLight ) {
var uniforms = cache.get( light );
// (a) intensity is the total visible light emitted
//uniforms.color.copy( color ).multiplyScalar( intensity / ( light.width * light.height * Math.PI ) );
// (b) intensity is the brightness of the light
uniforms.color.copy( color ).multiplyScalar( intensity );
uniforms.position.setFromMatrixPosition( light.matrixWorld );
uniforms.position.applyMatrix4( viewMatrix );
// extract local rotation of light to derive width/height half vectors
matrix42.identity();
matrix4.copy( light.matrixWorld );
matrix4.premultiply( viewMatrix );
matrix42.extractRotation( matrix4 );
uniforms.halfWidth.set( light.width * 0.5, 0.0, 0.0 );
uniforms.halfHeight.set( 0.0, light.height * 0.5, 0.0 );
uniforms.halfWidth.applyMatrix4( matrix42 );
uniforms.halfHeight.applyMatrix4( matrix42 );
// TODO (abelnation): RectAreaLight distance?
// uniforms.distance = distance;
state.rectArea[ rectAreaLength ] = uniforms;
rectAreaLength ++;
} else if ( light.isPointLight ) {
var uniforms = cache.get( light );
uniforms.position.setFromMatrixPosition( light.matrixWorld );
uniforms.position.applyMatrix4( viewMatrix );
uniforms.color.copy( light.color ).multiplyScalar( light.intensity );
uniforms.distance = light.distance;
uniforms.decay = light.decay;
uniforms.shadow = light.castShadow;
if ( light.castShadow ) {
var shadow = light.shadow;
uniforms.shadowBias = shadow.bias;
uniforms.shadowRadius = shadow.radius;
uniforms.shadowMapSize = shadow.mapSize;
uniforms.shadowCameraNear = shadow.camera.near;
uniforms.shadowCameraFar = shadow.camera.far;
}
state.pointShadowMap[ pointLength ] = shadowMap;
state.pointShadowMatrix[ pointLength ] = light.shadow.matrix;
state.point[ pointLength ] = uniforms;
pointLength ++;
} else if ( light.isHemisphereLight ) {
var uniforms = cache.get( light );
uniforms.direction.setFromMatrixPosition( light.matrixWorld );
uniforms.direction.transformDirection( viewMatrix );
uniforms.direction.normalize();
uniforms.skyColor.copy( light.color ).multiplyScalar( intensity );
uniforms.groundColor.copy( light.groundColor ).multiplyScalar( intensity );
state.hemi[ hemiLength ] = uniforms;
hemiLength ++;
}
}
state.ambient[ 0 ] = r;
state.ambient[ 1 ] = g;
state.ambient[ 2 ] = b;
state.directional.length = directionalLength;
state.spot.length = spotLength;
state.rectArea.length = rectAreaLength;
state.point.length = pointLength;
state.hemi.length = hemiLength;
state.hash.stateID = state.id;
state.hash.directionalLength = directionalLength;
state.hash.pointLength = pointLength;
state.hash.spotLength = spotLength;
state.hash.rectAreaLength = rectAreaLength;
state.hash.hemiLength = hemiLength;
state.hash.shadowsLength = shadows.length;
}
上面的代码是将灯光装换成uniforms数据，最终传递给GLSL。
- 上面的流程中并没有将灯光进行传递，接下来。回到render方法，设置了灯光之后，设置渲染目标，确定背景，接下来调用renderObjects去渲染场景下的所有网格。
- renderObjects通过循环调用renderObject
- renderobject通过判断是否需要即时渲染而调用renderObjectImmediate，或者使用renderBufferDirect。
- 最终 renderObjectImmediate和renderBufferDirect都会调用setProgram().
- 在setProgram()中会判断是否需要initMaterial()；
- 在getParameters的时候，会将lights全部设置到属性中
var parameters = programCache.getParameters(
material,
lights.state,
shadowsArray,
fog,
_clipping.numPlanes,
_clipping.numIntersection,
object );
总结一下
- 当render的时候，threejs会先初始化renderState
- 为renderState添加sense中的lights，
- 在renderObject时，将材质中的lights合并到renderState中。
- 最后通过webGLPrograms.getParamesters(),将光照设置到Programs中。
