GAMES101-现代计算机图形学学习笔记（4）作业3
前言
上篇作业2
本篇将更新作业3相关内容
作业3相关链接
games的作业3链接
我的源码
作业3简述
- 插值计算
- 各种shader实现
作业3相关知识笔记
- Barycentric Coordinates
- Blinn -Phong(Lambertian(Diffuse) Shading、Specular Shading、Ambient Shading)
- Flat shading、Gouraud shading、Phong shading
- Texture Magnification（Nearest、Bilinear、Bicubic)
- MipMap(Range Query、Trilinear interpolation)
- Anisotropic Filtering 、EWA filtering
- Environment Map(Spherical Environment Map)、Cube Map 、Bump/normal map 、 Displacement mapping
作业3思路
注意：后面有代码展示，一定要自己先做一遍再看，而且我的设计不一定正确规范高效。
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根据作业2补充上透视矩阵，这里就不再赘述了
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实现rasterize_triangle（）插值
void rst::rasterizer::rasterize_triangle(const Triangle& t, const std::array运行效果：
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补充 phong_fragment_shader()
Eigen::Vector3f phong_fragment_shader(const fragment_shader_payload& payload) { Eigen::Vector3f ka = Eigen::Vector3f(0.005, 0.005, 0.005); Eigen::Vector3f kd = payload.color; Eigen::Vector3f ks = Eigen::Vector3f(0.7937, 0.7937, 0.7937); auto l1 = light{{20, 20, 20}, {500, 500, 500}}; auto l2 = light{{-20, 20, 0}, {500, 500, 500}}; std::vectorlights = {l1, l2}; Eigen::Vector3f amb_light_intensity{10, 10, 10}; Eigen::Vector3f eye_pos{0, 0, 10}; float p = 150; Eigen::Vector3f color = payload.color; Eigen::Vector3f point = payload.view_pos; Eigen::Vector3f normal = payload.normal; Eigen::Vector3f result_color = {0, 0, 0}; Eigen::Vector3f v = (eye_pos - point).normalized(); for (auto& light : lights) { // TODO: For each light source in the code, calculate what the *ambient*, *diffuse*, and *specular* // components are. Then, accumulate that result on the *result_color* object. Eigen::Vector3f l = (light.position - point).normalized(); Eigen::Vector3f h = (v + l).normalized(); auto r2 = (light.position - point).squaredNorm(); auto ambient = ka.cwiseProduct(amb_light_intensity); auto diffuse = kd.cwiseProduct(light.intensity/r2 * MAX(0.0f,normal.dot(l))); auto specular = ks.cwiseProduct(light.intensity/r2 * std::pow(MAX(0.0f,normal.dot(h)),p)); result_color += ambient + diffuse + specular; } return result_color * 255.f; } 运行效果：
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补充texture_fragment_shader()
Eigen::Vector3f texture_fragment_shader(const fragment_shader_payload& payload) { Eigen::Vector3f return_color = {0, 0, 0}; if (payload.texture) { // TODO: Get the texture value at the texture coordinates of the current fragment return_color = payload.texture -> getColor(payload.tex_coords.x(),payload.tex_coords.y()); //return_color = payload.texture -> getColorBilinear(payload.tex_coords.x(),payload.tex_coords.y()); } Eigen::Vector3f texture_color; texture_color << return_color.x(), return_color.y(), return_color.z(); Eigen::Vector3f ka = Eigen::Vector3f(0.005, 0.005, 0.005); Eigen::Vector3f kd = texture_color / 255.f; Eigen::Vector3f ks = Eigen::Vector3f(0.7937, 0.7937, 0.7937); auto l1 = light{{20, 20, 20}, {500, 500, 500}}; auto l2 = light{{-20, 20, 0}, {500, 500, 500}}; std::vectorlights = {l1, l2}; Eigen::Vector3f amb_light_intensity{10, 10, 10}; Eigen::Vector3f eye_pos{0, 0, 10}; float p = 150; Eigen::Vector3f color = texture_color; Eigen::Vector3f point = payload.view_pos; Eigen::Vector3f normal = payload.normal; Eigen::Vector3f result_color = {0, 0, 0}; Eigen::Vector3f v = (eye_pos - point).normalized(); for (auto& light : lights) { // TODO: For each light source in the code, calculate what the *ambient*, *diffuse*, and *specular* // components are. Then, accumulate that result on the *result_color* object. Eigen::Vector3f l = (light.position - point).normalized(); Eigen::Vector3f h = (v + l).normalized(); auto r2 = (light.position - point).squaredNorm(); auto ambient = ka.cwiseProduct(amb_light_intensity); auto diffuse = kd.cwiseProduct(light.intensity/r2 * MAX(0.0f,normal.dot(l))); auto specular = ks.cwiseProduct(light.intensity/r2 * std::pow(MAX(0.0f,normal.dot(h)),p)); result_color += ambient + diffuse + specular; } return result_color * 255.f; } 运行效果：
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补充bump_fragment_shader()
Eigen::Vector3f bump_fragment_shader(const fragment_shader_payload& payload) { Eigen::Vector3f ka = Eigen::Vector3f(0.005, 0.005, 0.005); Eigen::Vector3f kd = payload.color; Eigen::Vector3f ks = Eigen::Vector3f(0.7937, 0.7937, 0.7937); auto l1 = light{{20, 20, 20}, {500, 500, 500}}; auto l2 = light{{-20, 20, 0}, {500, 500, 500}}; std::vectorlights = {l1, l2}; Eigen::Vector3f amb_light_intensity{10, 10, 10}; Eigen::Vector3f eye_pos{0, 0, 10}; float p = 150; Eigen::Vector3f color = payload.color; Eigen::Vector3f point = payload.view_pos; Eigen::Vector3f normal = payload.normal; float kh = 0.2, kn = 0.1; // TODO: Implement bump mapping here //Let n = normal = (x, y, z) Eigen::Vector3f n = normal; float x = n.x(); float y = n.y(); float z = n.z(); //Vector t = (x*y/sqrt(x*x+z*z),sqrt(x*x+z*z),z*y/sqrt(x*x+z*z)) Eigen::Vector3f t = {x*y/sqrt(x*x+z*z),sqrt(x*x+z*z),z*y/sqrt(x*x+z*z)}; //Vector b = n cross product t Eigen::Vector3f b = n.cross(t); t.normalize(); b.normalize(); //Matrix TBN = [t b n] Eigen::Matrix3f TBN = Eigen::Matrix3f::Identity(); TBN << t.x(),b.x(),n.x(),\ t.y(),b.y(),n.y(),\ t.z(),b.z(),n.z(); //dU = kh * kn * (h(u+1/w,v)-h(u,v)) //dV = kh * kn * (h(u,v+1/h)-h(u,v)) //Vector ln = (-dU, -dV, 1) float u = payload.tex_coords.x(); float v = payload.tex_coords.y(); float w = payload.texture -> width; float h = payload.texture -> height; float dU = kh * kn * (payload.texture -> getColor(u+1.0f/w,v).norm() - payload.texture -> getColor (u,v).norm()); float dV = kh * kn * (payload.texture -> getColor(u,v+1.0f/h).norm() - payload.texture -> getColor(u,v).norm()); Eigen::Vector3f ln = Eigen::Vector3f(-dU,-dV,1).normalized(); //Normal n = normalize(TBN * ln) normal = (TBN * ln).normalized(); Eigen::Vector3f result_color = {0, 0, 0}; result_color = normal; return result_color * 255.f; } 运行效果：
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补充displacement_fragment_shader()
Eigen::Vector3f displacement_fragment_shader(const fragment_shader_payload& payload) { Eigen::Vector3f ka = Eigen::Vector3f(0.005, 0.005, 0.005); Eigen::Vector3f kd = payload.color; Eigen::Vector3f ks = Eigen::Vector3f(0.7937, 0.7937, 0.7937); auto l1 = light{{20, 20, 20}, {500, 500, 500}}; auto l2 = light{{-20, 20, 0}, {500, 500, 500}}; std::vectorlights = {l1, l2}; Eigen::Vector3f amb_light_intensity{10, 10, 10}; Eigen::Vector3f eye_pos{0, 0, 10}; float p = 150; Eigen::Vector3f color = payload.color; Eigen::Vector3f point = payload.view_pos; Eigen::Vector3f normal = payload.normal; float kh = 0.2, kn = 0.1; // TODO: Implement displacement mapping here // Let n = normal = (x, y, z) Eigen::Vector3f n = normal; float x = n.x(); float y = n.y(); float z = n.z(); // Vector t = (x*y/sqrt(x*x+z*z),sqrt(x*x+z*z),z*y/sqrt(x*x+z*z)) Eigen::Vector3f t = {x*y/sqrt(x*x+z*z),sqrt(x*x+z*z),z*y/sqrt(x*x+z*z)}; // Vector b = n cross product t Eigen::Vector3f b = n.cross(t); t.normalize(); b.normalize(); // Matrix TBN = [t b n] Eigen::Matrix3f TBN = Eigen::Matrix3f::Identity(); TBN << t.x(),b.x(),n.x(),\ t.y(),b.y(),n.y(),\ t.z(),b.z(),n.z(); // dU = kh * kn * (h(u+1/w,v)-h(u,v)) // dV = kh * kn * (h(u,v+1/h)-h(u,v)) // Vector ln = (-dU, -dV, 1) float u = payload.tex_coords.x(); float v = payload.tex_coords.y(); float w = payload.texture -> width; float h = payload.texture -> height; float dU = kh * kn * (payload.texture -> getColor(u+1.0f/w,v).norm() - payload.texture -> getColor (u,v).norm()); float dV = kh * kn * (payload.texture -> getColor(u,v+1.0f/h).norm() - payload.texture -> getColor(u,v).norm()); Eigen::Vector3f ln = Eigen::Vector3f(-dU,-dV,1).normalized(); // Position p = p + kn * n * h(u,v) point += kn * n * (payload.texture -> getColor (u,v).norm()); // Normal n = normalize(TBN * ln) normal = (TBN * ln).normalized(); Eigen::Vector3f result_color = {0, 0, 0}; Eigen::Vector3f view = (eye_pos - point).normalized(); for (auto& light : lights) { // TODO: For each light source in the code, calculate what the *ambient*, *diffuse*, and *specular* // components are. Then, accumulate that result on the *result_color* object. Eigen::Vector3f l = (light.position - point).normalized(); Eigen::Vector3f h = (view + l).normalized(); auto r2 = (light.position - point).squaredNorm(); auto ambient = ka.cwiseProduct(amb_light_intensity); auto diffuse = kd.cwiseProduct(light.intensity/r2 * MAX(0.0f,normal.dot(l))); auto specular = ks.cwiseProduct(light.intensity/r2 * std::pow(MAX(0.0f,normal.dot(h)),p)); result_color += ambient + diffuse + specular; } return result_color * 255.f; } 运行效果：
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提高部分
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换用其他模型，更改main.cpp中obj_path和对应obj文件、texture文件即可
这里为了方便观察我另外修改了eye_pos,注意不要过近。
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双线性插值
Eigen::Vector3f getColorBilinear(float u,float v) { if(u<0)u=0; if(u>1)u=1; if(v<0)v=0; if(v>1)v=1; auto u_img = u * (width - 1); auto v_img = (1 - v) * (height - 1); /* Eigen::Vector2f u00(std::floor(u_img), std::floor(v_img)); Eigen::Vector2f u10(std::ceil(u_img), std::floor(v_img)); Eigen::Vector2f u00(std::floor(u_img), std::ceil(v_img)); Eigen::Vector2f u00(std::ceil(u_img), std::ceil(v_img)); */ auto color00 = getColor((std::floor(u_img))/width,1-(std::floor(v_img))/height); auto color10 = getColor((std::ceil(u_img))/width, 1-(std::floor(v_img))/height); auto color01 = getColor((std::floor(u_img))/width,1-(std::ceil(v_img))/height); auto color11 = getColor((std::ceil(u_img))/width, 1-(std::ceil(v_img))/height); float s = u_img - std::floor(u_img); float t = v_img - std::floor(v_img); auto color0 = lerp(s,color00,color10); auto color1 = lerp(s,color10,color11); auto color = lerp(s,color0,color1); return Eigen::Vector3f(color[0], color[1], color[2]); }Eigen::Vector3f lerp(float coefficient,Eigen::Vector3f color_a,Eigen::Vector3f color_b) { return (1-coefficient) * color_a + coefficient * color_b; }对比：
边缘细节显然双插值更好。
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