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| #define GLEW_STATIC
#include <GL/glew.h>
#include <GL/GL.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#pragma region Setting
static GLFWwindow* window;
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
const unsigned int MAX_COUNT = 800 * 600;
static void InitializeWindow()
{
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Test", NULL, NULL);
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, [](GLFWwindow* window, int width, int height) { glViewport(0, 0, width, height); });
glewExperimental = GL_TRUE;
glewInit();
}
static void ProcessInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
#pragma endregion
#pragma region InitializeVertex
static struct point
{
int x, y;
point() : x(0), y(0) {}
point(int _x, int _y) : x(_x), y(_y) {}
};
static float vertices[MAX_COUNT * 3 * 2];
static unsigned int VAO, VBO;
static unsigned int count = 0;
static void Normalize(float& x, float& y)
{
x = (x - (SCR_WIDTH / 2)) / (SCR_WIDTH / 2);
y = (y - (SCR_HEIGHT / 2)) / (SCR_HEIGHT / 2);
}
template <typename T>
static void Swap(T& a, T& b) { T temp(a); a = b; b = temp; }
const int LEFT = SCR_WIDTH / 4;
const int RIGHT = SCR_WIDTH / 4 * 3;
const int BOTTOM = SCR_HEIGHT / 4;
const int TOP = SCR_HEIGHT / 4 * 3;
static void DrawBoundary()
{
for (int i = 0; i < SCR_HEIGHT; i++)
{
vertices[count * 3] = LEFT, vertices[count * 3 + 1] = i;
Normalize(vertices[count * 3], vertices[count * 3 + 1]), count++;
vertices[count * 3] = RIGHT, vertices[count * 3 + 1] = i;
Normalize(vertices[count * 3], vertices[count * 3 + 1]), count++;
}
for (int i = 0; i < SCR_WIDTH; i++)
{
vertices[count * 3] = i, vertices[count * 3 + 1] = BOTTOM;
Normalize(vertices[count * 3], vertices[count * 3 + 1]), count++;
vertices[count * 3] = i, vertices[count * 3 + 1] = TOP;
Normalize(vertices[count * 3], vertices[count * 3 + 1]), count++;
}
}
static void Bresenham(int x1, int y1, int x2, int y2)
{
bool steep = abs(y2 - y1) > abs(x2 - x1);
if (steep) Swap(x1, y1), Swap(x2, y2);
if (x1 > x2) Swap(x1, x2), Swap(y1, y2);
int dx = x2 - x1, dy = y2 - y1;
int d = -dx;
for (int i = 0, x = x1, y = y1; i <= dx; i++, count++)
{
vertices[count * 3] = !steep ? x : y;
vertices[count * 3 + 1] = !steep ? y : x;
Normalize(vertices[count * 3], vertices[count * 3 + 1]);
x++;
d += 2 * abs(dy);
if (d > 0) y += (dy > 0 ? 1 : -1), d -= 2 * dx;
}
}
const int IN_SIDE = 0x0000;
const int LEFT_SIDE = 0x0001;
const int RIGHT_SIDE = 0x0010;
const int BOTTOM_SIDE = 0x0100;
const int TOP_SIDE = 0x1000;
static int EncodePoint(int x, int y)
{
int code = IN_SIDE;
if (x < LEFT) code |= LEFT_SIDE;
if (RIGHT < x) code |= RIGHT_SIDE;
if (y < BOTTOM) code |= BOTTOM_SIDE;
if (TOP < y) code |= TOP_SIDE;
return code;
}
static void CohenSutherland(int x0, int y0, int x1, int y1)
{
int code0 = EncodePoint(x0, y0), code1 = EncodePoint(x1, y1);
for (;;)
{
if ( (code0 | code1) == 0 ) break;
if ( (code0 & code1) != 0 ) return;
int outCode = code0 ? code0 : code1;
double x, y, z;
if (outCode & LEFT_SIDE) { x = LEFT; float t = (x - x0) / (x1 - x0); y = (1 - t) * y0 + t * y1; }
else if(outCode & RIGHT_SIDE) { x = RIGHT; float t = (x - x0) / (x1 - x0); y = (1 - t) * y0 + t * y1; }
else if(outCode & BOTTOM_SIDE) { y = BOTTOM; float t = (y - y0) / (y1 - y0); x = (1 - t) * x0 + t * x1; }
else if(outCode & TOP_SIDE) { y = TOP; float t = (y - y0) / (y1 - y0); x = (1 - t) * x0 + t * x1; }
if (outCode == code0) x0 = x, y0 = y, code0 = EncodePoint(x0, y0);
else x1 = x, y1 = y, code1 = EncodePoint(x1, y1);
}
Bresenham(x0, y0, x1, y1);
}
static void InitializeVertex()
{
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
}
#pragma endregion
void Render()
{
glClearColor(0.5, 0.5, 0.5, 1);
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(VAO);
glDrawArrays(GL_POINTS, 0, count);
}
int main()
{
int x0, y0, x1, y1;
std::cin >> x0 >> y0 >> x1 >> y1;
InitializeWindow();
DrawBoundary();
CohenSutherland(x0, y0, x1, y1);
InitializeVertex();
while (!glfwWindowShouldClose(window))
{
ProcessInput(window);
Render();
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
|
