#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtx/string_cast.hpp>
#include<glm/gtc/type_ptr.hpp>
#include <iostream>
#include <vector>

#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

using point3 = glm::vec3;
using vec3 = glm::vec3;
struct ray
{
    const point3 orig;
    const vec3 dir;
    ray(const point3& o, const point3& d) : orig(o), dir(d)
    {    }

    point3 at(float t) {return orig + t*dir;}
};

void save_fig(const int& width, const int& height, const std::string& fname)
{
    const int channel_num = 3;
    std::vector<uint8_t> pixels(width*height*channel_num, 0);

    int index=0;
    for(int j = height-1; j>=0; j--)
    {
        for(int i = 0; i< width; i++)
        {
            float r = (1.f*i)/width;
            float g = (1.f*j)/height;
            float b = 0.3;
            int ir = int(255.99 * r);
            int ig = int(255.99 * g);
            int ib = int(255.99 * b);

            pixels[index++]= ir;
            pixels[index++]= ig;
            pixels[index++]= ib;
        }
    }

    stbi_write_png(fname.c_str(), width, height, channel_num, pixels.data(), width*channel_num);
}
int main()
{
    point3 eye = point3(0);
    vec3 dir = vec3(1, 1, 0);
    ray r(eye, dir);
    std::cout << glm::to_string(r.orig) << "\n";

    std::cout << glm::to_string(r.at(2)) << "\n";

    glm::vec4 pos00(0, 1, 0, 0);

    std::cout << glm::to_string(pos00) <<"\n";
    glm::vec3 pos01(2.5);
    std::cout << glm::to_string(pos01) <<"\n";

    glm::vec4 pos02(pos01, 1);
    std::cout << glm::to_string(pos02) <<"\n";

    glm::mat4 model = glm::mat4(1);
    std::cout << glm::to_string(model) <<"\n";
    glm::vec4 t1 = pos02 * model;
    std::cout << glm::to_string(t1) <<"\n";

    float* pm = glm::value_ptr(model);

    save_fig(200, 100, "slika_00.png");
    return 0;

}

C++ Online Compiler

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!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}