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181 lines
4.9 KiB
181 lines
4.9 KiB
#include <iostream>
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#include <fstream>
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#include <sstream>
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#include <variant>
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#include <chrono>
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#include "commander.hpp"
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#include "nlohmann/json.hpp"
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#include <GL/glew.h>
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#define GLFW_DLL
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#include <GLFW/glfw3.h>
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std::variant<std::array<float,18>, std::vector<float>> points = std::array<float,18> {
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-1.0f, 1.0f, 0.0f,
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1.0f, -1.0f, 0.0f,
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-1.0f, -1.0f, 0.0f,
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1.0f, -1.0f, 0.0f,
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1.0f, 1.0f, 0.0f,
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-1.0f, 1.0f, 0.0f
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};
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std::string check_shader(GLuint shader)
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{
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std::array<char,4096> text_buffer;
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GLsizei size;
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glGetShaderInfoLog(shader, text_buffer.size(),&size,text_buffer.data());
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return std::string{text_buffer.begin(), text_buffer.begin()+size};
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}
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std::string vertex_shader =
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"#version 400\n"
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"in vec3 vp;"
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"void main() {"
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" gl_Position = vec4(vp, 1.0);"
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"}";
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std::string fragment_shader =
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"#version 400\n"
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"out vec4 frag_colour;"
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"void main() {"
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" frag_colour = vec4(1.0, 0.0, 0.0, 1.0);"
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"}";
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std::pair<int,int> parse_resolution(const std::string& str)
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{
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auto x_it = std::find(str.begin(),str.end(),'x');
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auto x_str = std::string{str.begin(),x_it};
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auto y_str = std::string(x_it+1,str.end());
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return std::make_pair(std::stoi(x_str),std::stoi(y_str));
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}
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std::string slurp_file(const std::string& path)
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{
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std::ifstream input(path);
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std::stringstream sstr;
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while(input >> sstr.rdbuf());
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return sstr.str();
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}
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int main(int argc, char** argv)
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{
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// start GL context and O/S window using the GLFW helper library
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if (!glfwInit()) {
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std::cerr<<"ERROR: could not start GLFW3\n";
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return 1;
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}
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CMD::commander cli_args{argc,argv};
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auto res_str = cli_args.getFlagValue("-r");
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auto res = parse_resolution(res_str.empty()?"800x800":res_str);
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auto mesh_path = cli_args.getFlagValue("--mesh");
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if(!mesh_path.empty()) {
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auto mesh = nlohmann::json::parse(slurp_file(mesh_path));
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assert(mesh.is_array());
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points = std::vector<float>{mesh.begin(), mesh.end()};
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}
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auto vertshad_path = cli_args.getFlagValue("--vshader");
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if(!vertshad_path.empty()) {
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vertex_shader = slurp_file(vertshad_path);
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}
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auto fragshad_path = cli_args.getFlagValue("--fshader");
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if(!fragshad_path.empty()) {
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fragment_shader = slurp_file(fragshad_path);
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}
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// uncomment these lines if on Apple OS X
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/*glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
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glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
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glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);*/
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GLFWwindow* window = glfwCreateWindow(res.first, res.second, "sh_render", NULL, NULL);
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if (!window) {
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std::cerr<<"ERROR: could not open window with GLFW3\n";
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glfwTerminate();
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return 1;
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}
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glfwMakeContextCurrent(window);
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// start GLEW extension handler
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glewExperimental = GL_TRUE;
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glewInit();
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// get version info
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const GLubyte* renderer = glGetString(GL_RENDERER); // get renderer string
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const GLubyte* version = glGetString(GL_VERSION); // version as a string
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std::cout <<"Renderer: "<<renderer<<"\n"
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<<"OpenGL version supported "<<version<<"\n";
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// tell GL to only draw onto a pixel if the shape is closer to the viewer
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glEnable(GL_DEPTH_TEST); // enable depth-testing
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glDepthFunc(GL_LESS); // depth-testing interprets a smaller value as "closer"
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{
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GLuint vbo = 0;
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glGenBuffers(1, &vbo);
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glBindBuffer(GL_ARRAY_BUFFER, vbo);
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glBufferData(
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GL_ARRAY_BUFFER,
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std::visit([](auto& v)->size_t{return v.size();},points) * sizeof(float),
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std::visit([](auto& v)->float* {return (float*)v.data();},points),
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GL_STATIC_DRAW
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);
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auto num_triangles = std::visit([](auto& v)->size_t{return v.size();},points)/9;
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GLuint vao = 0;
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glGenVertexArrays(1, &vao);
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glBindVertexArray(vao);
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glEnableVertexAttribArray(0);
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glBindBuffer(GL_ARRAY_BUFFER, vbo);
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glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
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GLuint vs = glCreateShader(GL_VERTEX_SHADER);
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auto vsh = vertex_shader.data();
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glShaderSource(vs, 1, &vsh, NULL);
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glCompileShader(vs);
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std::cout<<"Vertex shader:"<<check_shader(vs)<<"\n";
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GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
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auto fsh = fragment_shader.data();
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glShaderSource(fs, 1, &fsh, NULL);
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glCompileShader(fs);
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std::cout<<"Fragment shader:"<<check_shader(fs)<<"\n";
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GLuint shader_programme = glCreateProgram();
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glAttachShader(shader_programme, fs);
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glAttachShader(shader_programme, vs);
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glLinkProgram(shader_programme);
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while(!glfwWindowShouldClose(window)) {
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// wipe the drawing surface clear
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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glUseProgram(shader_programme);
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glBindVertexArray(vao);
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// draw points 0-4 from the currently bound VAO with current in-use shader
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for(size_t tri_it = 0; tri_it<num_triangles; tri_it++) {
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glDrawArrays(GL_TRIANGLES, tri_it*3, 3);
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}
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// update other events like input handling
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glfwPollEvents();
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// put the stuff we've been drawing onto the display
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glfwSwapBuffers(window);
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}
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}
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// close GL context and any other GLFW resources
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glfwTerminate();
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return 0;
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}
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