hello-triangle

#include <iostream>

// Include GLEW PRIJE GLFW!
#include <GL/glew.h>    // u ovom programu nije potrebno

// Include GLFW
#include <GLFW/glfw3.h>

// GLM
#include <glm/glm.hpp>  // u ovom programu nije potrebno
using namespace glm;

//[5]
#include "shader.h"

int main()
{
    // GLFW inicijalizacija
    if( !glfwInit() )
    {
        std::cerr << "GLFW nije inicijaliziran\n";
        getchar();
        return -1;
    }

    glfwWindowHint(GLFW_SAMPLES, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // samo za MacOS
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // kreiranje prozora i OpenGL context
    GLFWwindow* window = glfwCreateWindow( 1024, 768, "prog_01", nullptr, nullptr);
    if( window == nullptr )
    {
        std::cerr << "Nije prošao init glfw prozora. Npr. neki Intel GPU nisu 3.3 kompatibilni.\n";
        getchar();
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    // GLEW inicijalizacija
    if (glewInit() != GLEW_OK)
    {
        std::cerr << "GLEW nije inicijaliziran\n";
        getchar();
        glfwTerminate();
        return -1;
    }

    // sticky key press capture
    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

    // pozadina
    glClearColor(0.0f, 0.0f, 0.4f, 0.0f);

    //[1 Vertex Array Object
    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);
    //]
    // [2 An array of three vectors which represents three vertices
    static const GLfloat g_vertex_buffer_data[] = {
       -1.0f, -1.0f, 0.0f,
       1.0f, -1.0f, 0.0f,
       0.0f,  1.0f, 0.0f,
    };
    //]
    //[3
    GLuint vertexbuffer;    // This will identify our vertex buffer
    glGenBuffers(1, &vertexbuffer);     // Generate 1 buffer, put the resulting identifier in vertexbuffer
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);    // The following commands will talk about our 'vertexbuffer' buffer
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);  // Give our vertices to OpenGL.
    //]
    // [5] Create and compile our GLSL program from the shaders
    GLuint programID = loadShaders( "vertex.glsl", "fragment.glsl" );

    // napokon, loop
    do {
        // Brisanje ekrana
        // glClear( GL_COLOR_BUFFER_BIT );
        //[6
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glUseProgram(programID);    // Use our shader
        //]

        //[4 first attribute buffer : vertices
        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
        glVertexAttribPointer(
           0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
           3,                  // size
           GL_FLOAT,           // type
           GL_FALSE,           // normalized?
           0,                  // stride
           (void*)0            // array buffer offset
        );
        // Draw the triangle !
        glDrawArrays(GL_TRIANGLES, 0, 3); // Starting from vertex 0; 3 vertices total -> 1 triangle
        glDisableVertexAttribArray(0);
        //]

        // Swap buffers
        glfwSwapBuffers(window);
        glfwPollEvents();

    } // loop se vrti sve dok ne stisnemo ESC ili dok se prozor ne zatvori
    while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
           glfwWindowShouldClose(window) == 0 );

    // zatvaranje OpenGL prozora i GLFW
    glfwTerminate();

    return 0;
}