#include <vector>
#include <string>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <gl/gl_glew.h>
#include <GLFW/glfw3.h>
std::string vertShader = R"(
#version 460
layout(std430, binding = 0) buffer TVertex
{
vec4 vertex[];
};
uniform mat4 u_mvp;
uniform vec2 u_resolution;
uniform float u_thickness;
void main()
{
int line_i = gl_VertexID / 6;
int tri_i = gl_VertexID % 6;
vec4 va[4];
for (int i=0; i<4; ++i)
{
va[i] = u_mvp * vertex[line_i+i];
va[i].xyz /= va[i].w;
va[i].xy = (va[i].xy + 1.0) * 0.5 * u_resolution;
}
vec2 v_line = normalize(va[2].xy - va[1].xy);
vec2 nv_line = vec2(-v_line.y, v_line.x);
vec4 pos;
if (tri_i == 0 || tri_i == 1 || tri_i == 3)
{
vec2 v_pred = normalize(va[1].xy - va[0].xy);
vec2 v_miter = normalize(nv_line + vec2(-v_pred.y, v_pred.x));
pos = va[1];
pos.xy += v_miter * u_thickness * (tri_i == 1 ? -0.5 : 0.5) / dot(v_miter, nv_line);
}
else
{
vec2 v_succ = normalize(va[3].xy - va[2].xy);
vec2 v_miter = normalize(nv_line + vec2(-v_succ.y, v_succ.x));
pos = va[2];
pos.xy += v_miter * u_thickness * (tri_i == 5 ? 0.5 : -0.5) / dot(v_miter, nv_line);
}
pos.xy = pos.xy / u_resolution * 2.0 - 1.0;
pos.xyz *= pos.w;
gl_Position = pos;
}
)";
std::string fragShader = R"(
#version 460
out vec4 fragColor;
void main()
{
fragColor = vec4(1.0);
}
)";
// main
GLuint CreateSSBO(std::vector<glm::vec4> &varray)
{
GLuint ssbo;
glGenBuffers(1, &ssbo);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, ssbo );
glBufferData(GL_SHADER_STORAGE_BUFFER, varray.size()*sizeof(*varray.data()), varray.data(), GL_STATIC_DRAW);
return ssbo;
}
int main(void)
{
if ( glfwInit() == 0 )
throw std::runtime_error( "error initializing glfw" );
GLFWwindow *window = glfwCreateWindow( 800, 600, "GLFW OGL window", nullptr, nullptr );
if (window == nullptr)
{
glfwTerminate();
throw std::runtime_error("error initializing window");
}
glfwMakeContextCurrent(window);
if (glewInit() != GLEW_OK)
throw std::runtime_error("error initializing glew");
OpenGL::CContext::TDebugLevel debug_level = OpenGL::CContext::TDebugLevel::all;
OpenGL::CContext context;
context.Init( debug_level );
GLuint program = OpenGL::CreateProgram(vertShader, fragShader);
GLint loc_mvp = glGetUniformLocation(program, "u_mvp");
GLint loc_res = glGetUniformLocation(program, "u_resolution");
GLint loc_thi = glGetUniformLocation(program, "u_thickness");
glUseProgram(program);
glUniform1f(loc_thi, 20.0);
GLushort pattern = 0x18ff;
GLfloat factor = 2.0f;
std::vector<glm::vec4> varray;
varray.emplace_back(glm::vec4(0.0f, -1.0f, 0.0f, 1.0f));
varray.emplace_back(glm::vec4(1.0f, -1.0f, 0.0f, 1.0f));
for (int u=0; u <= 90; u += 10)
{
double a = u*M_PI/180.0;
double c = cos(a), s = sin(a);
varray.emplace_back(glm::vec4((float)c, (float)s, 0.0f, 1.0f));
}
varray.emplace_back(glm::vec4(-1.0f, 1.0f, 0.0f, 1.0f));
for (int u = 90; u >= 0; u -= 10)
{
double a = u * M_PI / 180.0;
double c = cos(a), s = sin(a);
varray.emplace_back(glm::vec4((float)c-1.0f, (float)s-1.0f, 0.0f, 1.0f));
}
varray.emplace_back(glm::vec4(1.0f, -1.0f, 0.0f, 1.0f));
varray.emplace_back(glm::vec4(1.0f, 0.0f, 0.0f, 1.0f));
GLuint ssbo = CreateSSBO(varray);
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, ssbo);
GLsizei N = (GLsizei)varray.size() - 2;
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glm::mat4(project);
int vpSize[2]{0, 0};
while (!glfwWindowShouldClose(window))
{
int w, h;
glfwGetFramebufferSize(window, &w, &h);
if (w != vpSize[0] || h != vpSize[1])
{
vpSize[0] = w; vpSize[1] = h;
glViewport(0, 0, vpSize[0], vpSize[1]);
float aspect = (float)w/(float)h;
project = glm::ortho(-aspect, aspect, -1.0f, 1.0f, -10.0f, 10.0f);
glUniform2f(loc_res, (float)w, (float)h);
}
glClear(GL_COLOR_BUFFER_BIT);
glm::mat4 modelview1( 1.0f );
modelview1 = glm::translate(modelview1, glm::vec3(-0.6f, 0.0f, 0.0f) );
modelview1 = glm::scale(modelview1, glm::vec3(0.5f, 0.5f, 1.0f) );
glm::mat4 mvp1 = project * modelview1;
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glUniformMatrix4fv(loc_mvp, 1, GL_FALSE, glm::value_ptr(mvp1));
glDrawArrays(GL_TRIANGLES, 0, 6*(N-1));
glm::mat4 modelview2( 1.0f );
modelview2 = glm::translate(modelview2, glm::vec3(0.6f, 0.0f, 0.0f) );
modelview2 = glm::scale(modelview2, glm::vec3(0.5f, 0.5f, 1.0f) );
glm::mat4 mvp2 = project * modelview2;
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glUniformMatrix4fv(loc_mvp, 1, GL_FALSE, glm::value_ptr(mvp2));
glDrawArrays(GL_TRIANGLES, 0, 6*(N-1));
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
} Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!
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