一、作业总览
本次作业框架添加了Object Loader(用于加载三维模型), Vertex Shader 与Fragment Shader,并且支持了纹理映射。
需要完成的任务:
- 修改函数
rasterize_triangle(const Triangle& t)
in rasterizer.cpp- 在此处实现与作业2类似的插值算法,实现法向量、颜色、纹理颜色的插值。
- 修改函数
get_projection_matrix()
in main.cpp- 将你自己在之前的实验中实现的投影矩阵填到此处,此时你可以运行./Rasterizer output.png normal来观察法向量实现结果。
- 修改函数
phong_fragment_shader()
in main.cpp- 实现Blinn-Phong 模型计算Fragment Color.
- 修改函数
texture_fragment_shader()
in main.cpp- 在实现Blinn-Phong的基础上,将纹理颜色视为公式中的kd,实现Texture Shading Fragment Shader.
- 修改函数
bump_fragment_shader()
in main.cpp- 在实现Blinn-Phong 的基础上,仔细阅读该函数中的注释,实现Bump mapping.
- 修改函数
displacement_fragment_shader()
in main.cpp- 在实现Bump mapping 的基础上,实现displacement mapping.
二、参考代码
2.1 rasterize_triangle(const Triangle& t)
- 类似作业2的插值
void rst::rasterizer::rasterize_triangle(const Triangle& t, const std::array<Eigen::Vector3f, 3>& view_pos)
{// TODO: From your HW3, get the triangle rasterization code.auto v = t.toVector4();// TODO : Find out the bounding box of current triangle.int bounding_box_x_left = std::min(v[0].x(), std::min(v[1].x(), v[2].x()));int bounding_box_x_right = std::max(v[0].x(), std::max(v[1].x(), v[2].x()));int bounding_box_y_left = std::min(v[0].y(), std::min(v[1].y(), v[2].y()));int bounding_box_y_right = std::max(v[0].y(), std::max(v[1].y(), v[2].y()));// TODO: Inside your rasterization loop:// * v[i].w() is the vertex view space depth value z.// * Z is interpolated view space depth for the current pixel// * zp is depth between zNear and zFar, used for z-bufferfor(int x = bounding_box_x_left; x <= bounding_box_x_right; x++){for(int y = bounding_box_y_left; y <= bounding_box_y_right; y++){if(insideTriangle(x, y, t.v)){auto[alpha, beta, gamma] = computeBarycentric2D(x, y, t.v);float Z = 1.0 / (alpha / v[0].w() + beta / v[1].w() + gamma / v[2].w());float zp = alpha * v[0].z() / v[0].w() + beta * v[1].z() / v[1].w() + gamma * v[2].z() / v[2].w();zp *= Z;if(zp < depth_buf[get_index(x, y)]){// TODO: Interpolate the attributes:auto interpolated_color = interpolate(alpha, beta, gamma, t.color[0], t.color[1], t.color[2], 1);auto interpolated_normal = interpolate(alpha, beta, gamma, t.normal[0], t.normal[1], t.normal[2], 1);auto interpolated_texcoords = interpolate(alpha, beta, gamma, t.tex_coords[0], t.tex_coords[1], t.tex_coords[2], 1);auto interpolated_shadingcoords = interpolate(alpha, beta, gamma, view_pos[0], view_pos[1], view_pos[2], 1);fragment_shader_payload payload( interpolated_color, interpolated_normal.normalized(), interpolated_texcoords, texture ? &*texture : nullptr);payload.view_pos = interpolated_shadingcoords;//Instead of passing the triangle's color directly to the frame buffer, pass the color to the shaders first to get the final color;auto pixel_color = fragment_shader(payload);set_pixel(Eigen::Vector2i(x, y), pixel_color);}}}}
}
2.2 get_projection_matrix()
- 投影矩阵,详细内容参考LAB1
Eigen::Matrix4f get_projection_matrix(float eye_fov, float aspect_ratio, float zNear, float zFar)
{// TODO: Use the same projection matrix from the previous assignmentEigen::Matrix4f projection = Eigen::Matrix4f::Identity();// TODO: Implement this function// Create the projection matrix for the given parameters.// Then return it.Eigen::Matrix4f persp_matrix;//透视矩阵 Eigen::Matrix4f translate_matrix;//移动矩阵Eigen::Matrix4f scale_matirx;//缩放矩阵persp_matrix << zNear, 0, 0, 0,0, zNear, 0, 0,0, 0, zNear + zFar, -zNear * zFar,0, 0, 1, 0;float halfAngle = eye_fov / 2 / 180 * MY_PI;float height = -2 * std::tan(halfAngle) * zNear;//没有负号则三角形上下颠倒float width = height * aspect_ratio;translate_matrix << 1, 0, 0, 0,0, 1, 0, 0, 0, 0, 1, -(zNear + zFar) / 2,0, 0, 0, 1;scale_matirx << 2 / width, 0, 0, 0,0, 2 / height, 0, 0,0, 0, 2 / (zNear - zFar), 0,0, 0, 0, 1;projection = scale_matirx * translate_matrix * persp_matrix;return projection;
}
2.3 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::vector<light> lights = {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};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.auto l = (light.position - point).normalized();auto v = (eye_pos - point).normalized();auto h = (l + v).normalized();//距离平方auto r_square = (light.position - point).squaredNorm();//cwiseProduct: 逐元素进行乘法auto La = ka.cwiseProduct(amb_light_intensity);auto Ld = kd.cwiseProduct(light.intensity / r_square) * MAX(0, normal.dot(l)); auto Ls = ks.cwiseProduct(light.intensity / r_square) * (pow (MAX(0, normal.dot(h)), p));result_color = La + Ld + Ls;}return result_color * 255.f;
}
2.4 texture_fragment_shader()
- 在实现Blinn-Phong的基础上,将纹理颜色视为公式中的kd,实现Texture Shading 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 fragmentfloat u = payload.tex_coords.x();float v = payload.tex_coords.y();//获得u,v对应的纹理颜色return_color = payload.texture->getColor(u, v);}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::vector<light> lights = {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};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.auto l = (light.position - point).normalized();auto v = (eye_pos - point).normalized();auto r_square = (light.position - point).squaredNorm();auto h = (l + v).normalized();auto La = ka.cwiseProduct(amb_light_intensity);auto Ld = kd.cwiseProduct(light.intensity / r_square) * MAX(0, normal.dot(l));auto Ls = ks.cwiseProduct(light.intensity / r_square) * pow( MAX(0, normal.dot(h)), p);result_color += La + Ld + Ls;}return result_color * 255.f;
}
2.5 bump_fragment_shader()
-
在实现Blinn-Phong 的基础上,实现Bump mapping.
- 法线贴图可以定义表面上任何不同位置的相对高度
- 相对高度发生变化,导致法线发生变化,导致shading发生变化(出现明暗对比)
- 逻辑上的高度改变
- 法线贴图可以定义表面上任何不同位置的相对高度
-
对于二维:
- 通过凹凸贴图算切线(1, dp);
- 求法线(-dp, 1)
-
对于三维:
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::vector<light> lights = {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)// Vector 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// Matrix TBN = [t b n]// 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)// Normal n = normalize(TBN * ln)auto x = normal.x();auto y = normal.y();auto z = normal.z();Vector3f t(x*y / sqrt(x*x+z*z), sqrt(x*x+z*z), z*y/sqrt(x*x+z*z));Vector3f b(normal.cross(t));Matrix3f TBN;TBN << t.x(), b.x(), normal.x(),t.y(), b.y(), normal.y(),t.z(), b.z(), normal.z();auto u = payload.tex_coords.x();auto v = payload.tex_coords.y();auto w = payload.texture->width;auto h = payload.texture->height;auto du = kh * kn * ( (payload.texture->getColor(u + 1.0f / w, v) - payload.texture->getColor(u, v)).norm() );auto dv = kh * kn * ( (payload.texture->getColor(u, v + 1.0 / h) - payload.texture->getColor(u, v)).norm() );Vector3f ln(-du, -dv, 1);normal = TBN * ln;Vector3f result_color = normal.normalized();return result_color * 255.f;
}
2.6 displacement_fragment_shader()
- 在实现Bump mapping 的基础上,实现displacement mapping.
- 几何体物理上表面高度改变
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::vector<light> lights = {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)// Vector 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// Matrix TBN = [t b n]// 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)// Position p = p + kn * n * h(u,v)// Normal n = normalize(TBN * ln)auto x = normal.x();auto y = normal.y();auto z = normal.z();Vector3f t(x*y / sqrt(x*x+z*z), sqrt(x*x+z*z), z*y/sqrt(x*x+z*z));Vector3f b(normal.cross(t));Matrix3f TBN;TBN << t.x(), b.x(), normal.x(),t.y(), b.y(), normal.y(),t.z(), b.z(), normal.z();auto u = payload.tex_coords.x();auto v = payload.tex_coords.y();auto w = payload.texture->width;auto h = payload.texture->height;auto du = kh * kn * ( (payload.texture->getColor(u + 1.0f / w, v) - payload.texture->getColor(u, v)).norm() );auto dv = kh * kn * ( (payload.texture->getColor(u, v + 1.0 / h) - payload.texture->getColor(u, v)).norm() );Vector3f ln{-du, -dv, 1.0f};// 目标点位置发生变化point = point + kn * normal * (payload.texture->getColor(u, v).norm());normal = TBN * ln;normal.normalized();Eigen::Vector3f result_color = {0, 0, 0};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.auto l = (light.position - point).normalized();auto v = (eye_pos - point).normalized();auto r_square = (light.position - point).squaredNorm();auto h = (l + v).normalized();auto La = ka.cwiseProduct(amb_light_intensity);auto Ld = kd.cwiseProduct(light.intensity / r_square) * MAX(0, normal.dot(l));auto Ls = ks.cwiseProduct(light.intensity / r_square) * pow( MAX(0, normal.dot(h)), p);result_color += La + Ld + Ls;}return result_color * 255.f;
}
三、编译
mkdir build
cd ./build
cmake …
make
texture: 使用代码中的texture shader.
使用举例: ./Rasterizer output.png texture
normal: 使用代码中的normal shader.
使用举例: ./Rasterizer output.png normal
phong: 使用代码中的blinn-phong shader.
使用举例: ./Rasterizer output.png phong
bump: 使用代码中的bump shader.
使用举例: ./Rasterizer output.png bump
displacement: 使用代码中的displacement shader.
使用举例: ./Rasterizer output.png displacement
当你修改代码之后,你需要重新make 才能看到新的结果
附件
作业3压缩包