QT+OpenGL材质
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材质
在现实世界中，每个物体会对光照产生不同的反应
在OpenGL中模拟多种类型的物体，必须为每种物体分别定义一个材质属性
struct Material { vec3 ambient; vec3 diffuse; vec3 specular; float shininess; } uniform Material material;
这个时候如果我们再去掉shader内写死的环境光的分量的话
#version 330 core struct Material { vec3 ambient; vec3 diffuse; vec3 specular; float shininess; }; uniform Material material; out vec4 FragColor; uniform vec3 lightColor; uniform vec3 lightPos; uniform vec3 viewPos; in vec3 Normal; in vec3 fragPos; void main() { // ambient vec3 ambient = lightColor; // diffuse vec3 norm = normalize(Normal); vec3 lightDir = normalize(lightPos - fragPos); float diff = max(dot(norm, lightDir), 0.0); vec3 diffuse = diff * lightColor; // specular vec3 viewDir = normalize(viewPos - fragPos); vec3 reflectDir = reflect(-lightDir, norm); float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32); vec3 specular = spec * lightColor; vec3 result = (ambient * material.ambient + diffuse * material.diffuse + specular * material.specular); FragColor = vec4(result, 1.0); }
整体显示会非常亮
添加材质，并且改变颜色
shader_program_.setUniformValue("material.ambient", 1.0f, 0.5f, 0.31f); shader_program_.setUniformValue("material.diffuse", 1.0f, 0.5f, 0.31f); shader_program_.setUniformValue("material.specular", 0.5f, 0.5f, 0.5f); shader_program_.setUniformValue("material.shininess", 32.0f); lightColor.setX(sin(time/100 *2.0f)); lightColor.setY(sin(time/100 *0.7f)); lightColor.setZ(sin(time/100 *1.3f)); QVector3D diffuseColor = lightColor * QVector3D(0.5, 0.5, 0.5); QVector3D ambientColor = lightColor * QVector3D(0.2, 0.2, 0.2); shader_program_.setUniformValue("light.ambient", ambientColor); shader_program_.setUniformValue("light.diffuse", diffuseColor); // 将光照调暗了一些以搭配场景 shader_program_.setUniformValue("light.specular", lightColor);
光照贴图
现实世界中的物体通常不只有一种材质，而是由多种材质组成
● 所以我们需要拓展之前的系统，引入漫反射和镜面光贴图
漫反射贴图
移除了环境材质颜色向量，因为环境光颜色在几乎所有情况下都等于漫反射颜色
注意sampler2D是所谓的不透明类型(Opaque Type)，也就是说我们不能将它实例化，只能通过uniform来定义它。如果我们使用除uniform以外的方法（比如函数的参数）实例化这个结构体，GLSL会抛出一些奇怪的错误。这同样也适用于任何封装了不透明类型的结构体。
struct Material { sampler2D diffuse; vec3 specular; float shininess; };
镜面光贴图
struct Material { sampler2D diffuse; sampler2D specular; float shininess; };
平行光
现实世界中，我们有很多种类的光照，每种的表现都不同。当一个光源处于很远的地方时，来自光源的每条光线就会近似于相互平行
struct Light { // vec3 position; // 使用定向光就不再需要了 vec3 direction; vec3 ambient; vec3 diffuse; vec3 specular; }; ... void main() { vec3 lightDir = normalize(-light.direction); ... }
点光源
点光源是处于世界中的某一个位置的光源，他会朝着所有方向发光，但是光线会随着距离逐渐衰减。想象作为投光物的火把或者灯泡，他们都是点光源。
衰减：
点光源会随着光线传播距离的增长逐渐削减光的强度。
衰减公式如下：
在这里d代表了片段距光源的距离。接下来为了计算衰减值，我们定义3个（可配置的）项：常数项Kc、一次项Kl和二次项Kq。
#version 330 core struct Material { sampler2D diffuse; sampler2D specular; float shininess; }; uniform Material material; struct Light { vec3 position; vec3 ambient; vec3 diffuse; vec3 specular; float constant; float linear; float quadratic; }; uniform Light light; out vec4 FragColor; uniform vec3 lightPos; uniform vec3 viewPos; in vec3 Normal; in vec3 fragPos; in vec2 TexCoords; void main() { vec3 diffuseColor = vec3(texture(material.diffuse, TexCoords)); vec3 specularColor = vec3(texture(material.specular, TexCoords)); float distance = length(light.position - fragPos); float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance)); // ambient vec3 ambient = diffuseColor * light.ambient; // diffuse vec3 norm = normalize(Normal); vec3 lightDir = normalize(light.position - fragPos); float diff = max(dot(norm, lightDir), 0.0); vec3 diffuse = diff * diffuseColor * light.diffuse; // specular vec3 viewDir = normalize(viewPos - fragPos); vec3 reflectDir = reflect(-lightDir, norm); float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32); vec3 specular = spec * light.specular * specularColor; // mix ambient *= attenuation; diffuse *= attenuation; specular *= attenuation; vec3 result = ambient + diffuse + specular; FragColor = vec4(result, 1.0); }
聚光
LightDir ： 从片段指向光源的向量
SpotDir： 聚光所指方向
Phi ϕ \phiϕ: 指定了聚光半径的切光角。落在这个角度之外的物体都不会被这个聚光所照亮
Theta θ \thetaθ：LightDir向量和SpotDir向量之间的夹角。在聚光内部的话θ \thetaθ值应该比ϕ \phiϕ值小。
手电筒就是普通的聚光灯，但是他的位置和方向会随着人的运动而改变。
#version 330 core struct Material { sampler2D diffuse; sampler2D specular; float shininess; }; uniform Material material; struct Light { vec3 position; vec3 direction; vec3 ambient; vec3 diffuse; vec3 specular; float constant; float linear; float quadratic; float cutOff; }; uniform Light light; out vec4 FragColor; uniform vec3 lightPos; uniform vec3 viewPos; in vec3 Normal; in vec3 fragPos; in vec2 TexCoords; void main() { vec3 diffuseColor = vec3(texture(material.diffuse, TexCoords)); vec3 specularColor = vec3(texture(material.specular, TexCoords)); vec3 lightDir = normalize(fragPos - light.position); float theta = dot(lightDir, normalize(light.direction)); if(theta > light.cutOff) { // ambient vec3 ambient = diffuseColor * light.ambient; // diffuse vec3 norm = normalize(Normal); vec3 lightDir = normalize(light.position - fragPos); float diff = max(dot(norm, lightDir), 0.0); vec3 diffuse = diff * diffuseColor * light.diffuse; // specular vec3 viewDir = normalize(viewPos - fragPos); vec3 reflectDir = reflect(-lightDir, norm); float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32); vec3 specular = spec * light.specular * specularColor; // attenuation float distance = length(light.position - fragPos); float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance)); // mix ambient *= attenuation; diffuse *= attenuation; specular *= attenuation; vec3 result = ambient + diffuse + specular; FragColor = vec4(result, 1.0); } else { FragColor = vec4(light.ambient * diffuseColor, 1.0); } }
聚光边缘太过生硬，因此需要对边缘进行平滑软化；公式如下
多光源
创建一个包含六个光源的场景，我们将模拟一个类似太阳的定向光源，四个分散在场景中的点光源和一个手电筒
#version 330 core struct Material { sampler2D diffuse; sampler2D specular; float shininess; }; uniform Material material; struct SpotLight { vec3 position; vec3 direction; vec3 ambient; vec3 diffuse; vec3 specular; float constant; float linear; float quadratic; float cutOff; float outerCutOff; }; struct DirLight { vec3 direction; vec3 ambient; vec3 diffuse; vec3 specular; }; uniform DirLight dirLight; uniform SpotLight spotLight; out vec4 FragColor; uniform vec3 lightPos; uniform vec3 viewPos; in vec3 Normal; in vec3 fragPos; in vec2 TexCoords; vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 viewDir); vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir); vec3 diffuseColor = vec3(texture(material.diffuse, TexCoords)); vec3 specularColor = vec3(texture(material.specular, TexCoords)); void main() { vec3 norm = normalize(Normal); vec3 viewDir = normalize(viewPos - fragPos); vec3 result = vec3(0); result += CalcSpotLight(spotLight, norm, viewDir); result += CalcDirLight(dirLight, norm, viewDir); FragColor = vec4(result, 1.0); } vec3 CalcSpotLight(SpotLight light, vec3 normal, vec3 viewDir) { vec3 lightDir = normalize(light.position - fragPos); // ambient vec3 ambient = diffuseColor * light.ambient; // diffuse float diff = max(dot(normal, lightDir), 0.0); vec3 diffuse = diff * diffuseColor * light.diffuse; // specular vec3 reflectDir = reflect(-lightDir, normal); float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess); vec3 specular = spec * light.specular * specularColor; // attenuation float distance = length(light.position - fragPos); float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance)); //ambient *= attenuation; diffuse *= attenuation; specular *= attenuation; //smooth float theta = dot(lightDir, normalize(-light.direction)); float epsilon = light.cutOff - light.outerCutOff; float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0); diffuse *= intensity; specular *= intensity; return (ambient + diffuse + specular); } vec3 CalcDirLight(DirLight light, vec3 normal, vec3 viewDir) { vec3 lightDir = normalize(-light.direction); // ambient float diff = max(dot(normal, lightDir), 0.0); // specular vec3 reflectDir = reflect(-lightDir, normal); float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess); // attenuation vec3 ambient = light.ambient * diffuseColor; vec3 diffuse = light.diffuse * diff * diffuseColor; vec3 specular = light.specular * spec * specularColor; return (ambient + diffuse + specular); }
光照部分到此结束， 实现部分请参照gitee代码。如果您不能运行，可以联系私信博主咨询。
