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| cmake_minimum_required(VERSION 3.10) # specify the version of cmake | ||
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| ############################# | ||
| # set C++ detail | ||
| enable_language(CXX) # we are using C++ | ||
| set(CMAKE_CXX_STANDARD 17) # we are using C++ 17 | ||
| set(CMAKE_CXX_STANDARD_REQUIRED TRUE) # we are using STL library | ||
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| ############################# | ||
| # set project name | ||
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| project(task02) | ||
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| ############################# | ||
| # define macro | ||
| add_definitions(-DPROJECT_SOURCE_DIR="${PROJECT_SOURCE_DIR}") | ||
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| ############################# | ||
| # specifying libraries to use | ||
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| ######################## | ||
| # include, build, and link | ||
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| include_directories( | ||
| ${PROJECT_SOURCE_DIR}/../external | ||
| ${PROJECT_SOURCE_DIR}/../external/eigen | ||
| ${PROJECT_SOURCE_DIR}/../src | ||
| ) | ||
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| add_executable(${PROJECT_NAME} | ||
| main.cpp | ||
| ) | ||
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| target_link_libraries(${PROJECT_NAME} | ||
| # stdc++fs # uncomment here if <filesystem> cannot be included | ||
| ) |
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| # Task01: Rasterization of parametric curves | ||
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| **Deadline: April 25st (Thu) at 15:00pm** | ||
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| This is the blurred preview of the expected result: | ||
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|  | ||
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| When you execute the program, it will output an PNG image file (`output.png`) replacing the image below. Try making the image below and the image above look similar after doing the assignment. | ||
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|  | ||
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| ---- | ||
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| ## Instruction | ||
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| Please follow this instruction to prepare the environment to do the assignment | ||
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| If you did not do the [task01](../task01) assignment, you need to prepare **git**, **cmake**, and **C++ compiler** in your computer to complete this assignment. | ||
| Read the following document to install these. | ||
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| [How to Set Up C++ Programming Environment](../doc/setup_env.md) | ||
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| If you had some trouble with `git` in the local repository in the previous assignment, `clone` your remote repository again to avoid trouble. | ||
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| ```bash | ||
| $ git clone https://github.com/ACG-2024S/acg-<username>.git | ||
| ``` | ||
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| Go to the top of the local repository | ||
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| ```bash | ||
| $ cd acg-<username> # go to the local repository | ||
| ``` | ||
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| ### Update Local Repository | ||
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| Update the local repository on your computer | ||
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| ```bash | ||
| $ git checkout main # set main branch as the current branch | ||
| $ git fetch origin main # download the main branch from remote repository | ||
| $ git reset --hard origin/main # reset the local main branch same as remote repository | ||
| ``` | ||
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| After this command, you will see the local repository is synced with the remote repository at `https://github.com/ACG-2024S/acg-<username>` | ||
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| ### Create a Branch | ||
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| To do this assignment, you need to be in the branch `task02`. | ||
| You can always check your the current branch by | ||
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| ```bash | ||
| $ git branch -a # list all branches, showing the current branch | ||
| ``` | ||
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| You are probably in the `main` branch. Let's create the `task02` branch and set it as the current branch. | ||
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| ```bash | ||
| $ git branch task02 # create task0 branch | ||
| $ git checkout task02 # switch into the task02 branch | ||
| $ git branch -a # make sure you are in the task02 branch | ||
| ``` | ||
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| The environment is ready. | ||
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| ## Problem1 | ||
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| Install eigen under `acg-<username>/external` by the following command | ||
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| ```bash | ||
| $ pwd # make sure you are in acg-<username> directory | ||
| $ git submodule update --init external/eigen # clone the "eigen" repository (this may take one or two minutes) | ||
| ``` | ||
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| Make sure you have a header file `Dense` at | ||
| ``` | ||
| acg-<username>/external/eigen/Eigen/Dense | ||
| ``` | ||
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| Eigen can be used as a header-only library. You do not need to compile it to do this task. | ||
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| Next, compile the code with **out-of-source** build by making a new directory for build `task02/build` and compile inside that directory | ||
| ```bash | ||
| $ cd task02 # you are in "acg-<username>/task02" directory | ||
| $ mkdir build | ||
| $ cd build | ||
| $ cmake -DCMAKE_BUILD_TYPE=Release .. # configure Release mode for fast execution | ||
| $ cmake --build . | ||
| ``` | ||
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| Now you will see the `output.png` is updated. The `output.png` will show an angular shape of the letter **R**. Now let's write a program to make the font shape smooth as the original one. | ||
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| ## Problem2 | ||
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| The code you compiled above uses the ***Jordan's curve theorem** to find whether the center of a pixel is inside or outside the character.The code counts the number of intersections of a ray against the boundary. | ||
| The boundary of the letter is represented by sequences of line segments and quadratic Bézier curves. The Problem1's output was angular because the Bézier curve was approximated as a line segment. | ||
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| Modify the code `main.cpp` around line #65 to compute the number of intersections of a ray against the Bézier curve. The output will be the letter ***R*** with smooth boundary. | ||
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| ### Submit | ||
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| Finally, you submit the document by pushing to the `task02` branch of the remote repository. | ||
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| ```bash | ||
| cd acg-<username> # go to the top of the repository | ||
| git status # check the changes | ||
| git add . # stage the changes | ||
| git status # check the staged changes | ||
| git commit -m "task02 finished" # the comment can be anything | ||
| git push --set-upstream origin task02 # update the task02 branch of the remote repository | ||
| ``` | ||
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| got to the GitHub webpage `https://github.com/ACG-2024S/acg-<username>`. | ||
| If everything looks good on this page, make a pull request. | ||
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|  | ||
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| ---- | ||
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| ## Trouble Shooting | ||
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| If you have trouble with `#include <filesystem>`, your C++ compilar is very old. Try update one. Following command may work tos specify which compilar to use on linux & Mac | ||
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| ``` | ||
| export CC=/usr/local/bin/gcc-8 | ||
| export CXX=/usr/local/bin/g++-8 | ||
| cmake .. | ||
| ``` | ||
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| ---- | ||
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| ## Reference | ||
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| - Coding Adventure: Rendering Text | ||
| : https://www.youtube.com/watch?v=SO83KQuuZvg | ||
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| - SIGGRAPH 2022 Talk - A Fast & Robust Solution for Cubic & Higher-Order Polynomials by Cem Yuksel: https://www.youtube.com/watch?v=ok0EZ0fBCMA | ||
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| - True Type: https://en.wikipedia.org/wiki/TrueType |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,105 @@ | ||
| #include <filesystem> | ||
| // #include <experimental/filesystem> // uncomment here if the <filesystem> cannot be included above | ||
| // | ||
| #define STB_IMAGE_WRITE_IMPLEMENTATION | ||
| #include "stb_image_write.h" | ||
| #include "Eigen/Core" | ||
| // | ||
| #include "parse_svg.h" | ||
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| /*** | ||
| * signed area of a triangle connecting points (p0, p1, p2) in counter-clockwise order. | ||
| * @param p0 1st point xy-coordinate | ||
| * @param p1 2nd point xy-coordinate | ||
| * @param p2 3rd point xy-coordinate | ||
| * @return signed area (float) | ||
| */ | ||
| float area( | ||
| const Eigen::Vector2f &p0, | ||
| const Eigen::Vector2f &p1, | ||
| const Eigen::Vector2f &p2) { | ||
| const auto v01 = p1 - p0; | ||
| const auto v02 = p2 - p0; | ||
| // return 0.5f * (v01[0] * v02[1] - v01[1] * v02[0]); // right handed coordinate | ||
| return 0.5f * (v01[1] * v02[0] - v01[0] * v02[1]); // left-handed coordinate (because pixel y-coordinate is going down) | ||
| } | ||
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| /*** | ||
| * compute number of intersection of a ray against a line segment | ||
| * @param org ray origin | ||
| * @param dir ray direction (unit normal) | ||
| * @param ps one of the two end points | ||
| * @param pe the other end point | ||
| * @return number of intersection | ||
| */ | ||
| int number_of_intersection_ray_against_edge( | ||
| const Eigen::Vector2f &org, | ||
| const Eigen::Vector2f &dir, | ||
| const Eigen::Vector2f &ps, | ||
| const Eigen::Vector2f &pe) { | ||
| auto a = area(org, org + dir, ps); | ||
| auto b = area(org, pe, org + dir); | ||
| auto c = area(org, ps, pe); | ||
| auto d = area(org + dir, ps, pe); | ||
| if (a * b > 0.f && d * c > 0.f && fabs(d) > fabs(c)) { return 1; } | ||
| return 0; | ||
| } | ||
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| /*** | ||
| * | ||
| * @param org ray origin | ||
| * @param dir ray direction (unit vector) | ||
| * @param ps one of the two end points | ||
| * @param pc control point | ||
| * @param pe the other end point | ||
| * @return the number of intersections | ||
| */ | ||
| int number_of_intersection_ray_against_quadratic_bezier( | ||
| const Eigen::Vector2f &org, | ||
| const Eigen::Vector2f &dir, | ||
| const Eigen::Vector2f &ps, | ||
| const Eigen::Vector2f &pc, | ||
| const Eigen::Vector2f &pe) { | ||
| // comment out below to do the assignment | ||
| return number_of_intersection_ray_against_edge(org, dir, ps, pe); | ||
| // write some code below to find the intersection between ray and the quadratic | ||
| } | ||
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| int main() { | ||
| const auto input_file_path = std::filesystem::path(PROJECT_SOURCE_DIR) / ".." / "asset" / "r.svg"; | ||
| const auto [width, height, shape] = acg::svg_get_image_size_and_shape(input_file_path); | ||
| if (width == 0) { // something went wrong in loading the function | ||
| std::cout << "file open failure" << std::endl; | ||
| abort(); | ||
| } | ||
| const std::vector<std::string> outline_path = acg::svg_outline_path_from_shape(shape); | ||
| const std::vector<std::vector<acg::Edge>> loops = acg::svg_loops_from_outline_path(outline_path); | ||
| // | ||
| std::vector<unsigned char> img_data(width * height, 255); // grayscale image initialized white | ||
| for (unsigned int ih = 0; ih < height; ++ih) { | ||
| for (unsigned int iw = 0; iw < width; ++iw) { | ||
| const auto org = Eigen::Vector2f(iw + 0.5, ih + 0.5); // pixel center | ||
| const auto dir = Eigen::Vector2f(60., 20.); // search direction | ||
| int count_cross = 0; | ||
| for (const auto &loop: loops) { // loop over loop (letter R have internal/external loops) | ||
| for (const auto &edge: loop) { // loop over edge in the loop | ||
| if (edge.is_bezier) { // in case the edge is a quadratic Bézier | ||
| count_cross += number_of_intersection_ray_against_quadratic_bezier( | ||
| org, dir, | ||
| edge.ps, edge.pc, edge.pe); | ||
| } else { // in case the edge is a line segment | ||
| count_cross += number_of_intersection_ray_against_edge( | ||
| org, dir, | ||
| edge.ps, edge.pe); | ||
| } | ||
| } | ||
| } | ||
| if (count_cross % 2 == 1) { // Jordan's curve theory | ||
| img_data[ih * width + iw] = 0; // paint black if it is inside | ||
| } | ||
| } | ||
| } | ||
| const auto output_file_path = std::filesystem::path(PROJECT_SOURCE_DIR) / "output.png"; | ||
| stbi_write_png(output_file_path.string().c_str(), width, height, 1, img_data.data(), width); | ||
| } |
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