( phong)明暗处理采用了法矢量双线性插值的方法先求出多边形内部各点法矢量再求颜色, ( )明暗处理采用了亮度双线性插值的方法求出多边形内部各点颜色。
时间: 2024-02-03 07:03:06 浏览: 16
第一个空应该是“Gouraud”,即Gouraud明暗处理采用了法矢量双线性插值的方法先求出多边形表面顶点法矢量,再根据光照模型计算每个顶点的颜色,最后使用插值算法计算多边形表面内部各点的颜色。第二个空应该是“Phong”,即Phong明暗处理采用了亮度双线性插值的方法先计算多边形表面内各点的法矢量,再根据光照模型计算每个点的颜色。这两种明暗处理方法都是计算机图形学中常见的光照处理方法。
相关问题
[1] 编码实现 Gouraud 明暗处理方法 [2] 编码实现 Phong 明暗处理方法
[1]
Gouraud 明暗处理方法是一种基于顶点颜色插值的渲染技术,可以实现较为逼真的光照效果。具体实现步骤如下:
1. 计算每个顶点的法向量和颜色值;
2. 对于每个光源,计算每个顶点的光照强度;
3. 对于每个像素,使用顶点颜色值的插值计算该像素的颜色值。
代码实现如下:
// 顶点结构体
struct Vertex {
vec3 position;
vec3 normal;
vec3 color;
};
// 光源结构体
struct Light {
vec3 position;
vec3 color;
};
// 计算顶点光照强度
float calculateIntensity(Vertex vertex, Light light) {
vec3 lightDirection = normalize(light.position - vertex.position);
float diffuse = max(dot(vertex.normal, lightDirection), 0.0);
return diffuse * length(light.color);
}
// Gouraud 明暗处理方法
void gouraudShading(Vertex vertex1, Vertex vertex2, Vertex vertex3, Light light) {
// 计算每个顶点的光照强度
float intensity1 = calculateIntensity(vertex1, light);
float intensity2 = calculateIntensity(vertex2, light);
float intensity3 = calculateIntensity(vertex3, light);
// 插值计算每个像素的颜色值
for (int i = 0; i < SCREEN_WIDTH; i++) {
for (int j = 0; j < SCREEN_HEIGHT; j++) {
vec2 pixel = vec2(i, j);
vec3 barycentric = calculateBarycentric(vertex1.position, vertex2.position, vertex3.position, pixel);
vec3 color = barycentric.x * vertex1.color + barycentric.y * vertex2.color + barycentric.z * vertex3.color;
float intensity = barycentric.x * intensity1 + barycentric.y * intensity2 + barycentric.z * intensity3;
setPixelColor(pixel, color * intensity);
}
}
}
[2]
Phong 明暗处理方法是一种基于像素法向量插值的渲染技术,可以实现更加真实的光照效果。具体实现步骤如下:
1. 计算每个顶点的法向量;
2. 对于每个像素,使用顶点法向量的插值计算该像素的法向量;
3. 对于每个光源,计算每个像素的光照强度;
4. 对于每个像素,使用插值后的法向量和光照强度计算该像素的颜色值。
代码实现如下:
// 计算像素法向量插值
vec3 calculateInterpolatedNormal(Vertex vertex1, Vertex vertex2, Vertex vertex3, vec2 pixel) {
vec3 barycentric = calculateBarycentric(vertex1.position, vertex2.position, vertex3.position, pixel);
vec3 normal1 = normalize(vertex1.normal);
vec3 normal2 = normalize(vertex2.normal);
vec3 normal3 = normalize(vertex3.normal);
return normalize(barycentric.x * normal1 + barycentric.y * normal2 + barycentric.z * normal3);
}
// 计算像素光照强度
float calculateIntensity(Vertex vertex, vec3 lightDirection, vec3 viewDirection, float specularPower) {
vec3 reflectDirection = reflect(-lightDirection, vertex.normal);
float diffuse = max(dot(vertex.normal, lightDirection), 0.0);
float specular = pow(max(dot(reflectDirection, viewDirection), 0.0), specularPower);
return diffuse + specular;
}
// Phong 明暗处理方法
void phongShading(Vertex vertex1, Vertex vertex2, Vertex vertex3, Light light, vec3 viewDirection, float specularPower) {
// 插值计算每个像素的法向量
for (int i = 0; i < SCREEN_WIDTH; i++) {
for (int j = 0; j < SCREEN_HEIGHT; j++) {
vec2 pixel = vec2(i, j);
vec3 normal = calculateInterpolatedNormal(vertex1, vertex2, vertex3, pixel);
// 计算每个像素的光照强度
vec3 lightDirection = normalize(light.position - pixel);
float intensity = calculateIntensity(vertex, lightDirection, viewDirection, specularPower);
// 计算每个像素的颜色值
vec3 color = vertex.color * intensity;
setPixelColor(pixel, color);
}
}
}
(1) 在必做题基础上添加Blinn-Phong光照模型,将光源设置为聚光灯模式,并模拟点光源的衰减;对于这个问题给出详细代码
好的,这里给出一个使用 Three.js 实现的带有 Blinn-Phong 光照模型和聚光灯模式的多个立方体的代码示例:
```javascript
// 初始化场景、相机、渲染器等
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
// 添加聚光灯光源
var spotLight = new THREE.SpotLight(0xffffff, 1);
spotLight.position.set(0, 100, 0);
spotLight.angle = Math.PI / 4;
spotLight.penumbra = 0.05;
spotLight.decay = 2;
spotLight.distance = 200;
scene.add(spotLight);
// 添加多个立方体
var cube1 = new THREE.Mesh(
new THREE.BoxGeometry(1, 1, 1),
new THREE.MeshPhongMaterial({ map: THREE.ImageUtils.loadTexture('texture1.png') })
);
cube1.position.set(-2, 0, -5);
scene.add(cube1);
var cube2 = new THREE.Mesh(
new THREE.BoxGeometry(1, 1, 1),
new THREE.MeshPhongMaterial({ map: THREE.ImageUtils.loadTexture('texture2.png') })
);
cube2.position.set(0, 0, -5);
scene.add(cube2);
var cube3 = new THREE.Mesh(
new THREE.BoxGeometry(1, 1, 1),
new THREE.MeshPhongMaterial({ map: THREE.ImageUtils.loadTexture('texture3.png') })
);
cube3.position.set(2, 0, -5);
scene.add(cube3);
// 设置相机位置和控制器
camera.position.z = 5;
var controls = new THREE.OrbitControls(camera, renderer.domElement);
// 渲染循环
function render() {
requestAnimationFrame(render);
// 计算每个立方体的 Blinn-Phong 光照
cube1.material.needsUpdate = true;
cube2.material.needsUpdate = true;
cube3.material.needsUpdate = true;
spotLight.position.copy(camera.position);
spotLight.lookAt(cube1.position);
var distance = spotLight.position.distanceTo(cube1.position);
var intensity = spotLight.intensity / (spotLight.decay * distance * distance);
cube1.material.uniforms.lightPosition.value = spotLight.position;
cube1.material.uniforms.lightColor.value = spotLight.color;
cube1.material.uniforms.lightIntensity.value = intensity;
cube1.material.uniforms.lightDistance.value = distance;
cube1.material.uniforms.lightAngle.value = spotLight.angle;
cube1.material.uniforms.lightPenumbra.value = spotLight.penumbra;
cube1.material.uniforms.lightDecay.value = spotLight.decay;
spotLight.lookAt(cube2.position);
distance = spotLight.position.distanceTo(cube2.position);
intensity = spotLight.intensity / (spotLight.decay * distance * distance);
cube2.material.uniforms.lightPosition.value = spotLight.position;
cube2.material.uniforms.lightColor.value = spotLight.color;
cube2.material.uniforms.lightIntensity.value = intensity;
cube2.material.uniforms.lightDistance.value = distance;
cube2.material.uniforms.lightAngle.value = spotLight.angle;
cube2.material.uniforms.lightPenumbra.value = spotLight.penumbra;
cube2.material.uniforms.lightDecay.value = spotLight.decay;
spotLight.lookAt(cube3.position);
distance = spotLight.position.distanceTo(cube3.position);
intensity = spotLight.intensity / (spotLight.decay * distance * distance);
cube3.material.uniforms.lightPosition.value = spotLight.position;
cube3.material.uniforms.lightColor.value = spotLight.color;
cube3.material.uniforms.lightIntensity.value = intensity;
cube3.material.uniforms.lightDistance.value = distance;
cube3.material.uniforms.lightAngle.value = spotLight.angle;
cube3.material.uniforms.lightPenumbra.value = spotLight.penumbra;
cube3.material.uniforms.lightDecay.value = spotLight.decay;
renderer.render(scene, camera);
}
render();
```
其中,纹理贴图的加载需要使用 `THREE.ImageUtils.loadTexture()` 方法,同时为了实现 Blinn-Phong 光照模型,需要在材质中添加 uniform 变量,并在渲染循环中对每个立方体的材质进行更新。具体的实现细节可以参考代码中的注释。