sample_gl2.cpp

// sample_gl2.cpp - public domain
// authored from 2012-2013 by Adrien Herubel 


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <cmath>
#include <iostream>

#include "glew/glew.h"
#ifdef __APPLE__
#include <OpenGL/gl.h>
#else
#include <GL/gl.h>
#endif
#include "GL/glfw.h"

#include "imgui.h"
#include "imguiRenderGL2.h"

int main( int argc, char **argv )
{
    int width = 1024, height=768;

    // Initialise GLFW
    if( !glfwInit() )
    {
        fprintf( stderr, "Failed to initialize GLFW\n" );
        exit( EXIT_FAILURE );
    }

    // Open a window and create its OpenGL context
    if( !glfwOpenWindow( width, height, 0,0,0,0, 24,0, GLFW_WINDOW ) )
    {
        fprintf( stderr, "Failed to open GLFW window\n" );
        glfwTerminate();
        exit( EXIT_FAILURE );
    }

    glfwSetWindowTitle( "imgui sample imguiRenderGL2" );
    GLenum err = glewInit();
    if (GLEW_OK != err)
    {
          /* Problem: glewInit failed, something is seriously wrong. */
          fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
          exit( EXIT_FAILURE );
    }

    // Ensure we can capture the escape key being pressed below
    glfwEnable( GLFW_STICKY_KEYS );

    // Enable vertical sync (on cards that support it)
    glfwSwapInterval( 1 );

    // Init UI
    if (!imguiRenderGLInit("DroidSans.ttf"))
    {
        fprintf(stderr, "Could not init GUI renderer.\n");
        exit(EXIT_FAILURE);
    }

    glClearColor(0.8f, 0.8f, 0.8f, 1.f);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glDisable(GL_DEPTH_TEST);

    // imgui states
    bool checked1 = false;
    bool checked2 = false;
    bool checked3 = true;
    bool checked4 = false;
    float value1 = 50.f;
    float value2 = 30.f;
    int scrollarea1 = 0;
    int scrollarea2 = 0;

    // glfw scrolling
    int glfwscroll = 0;
    do
    {
        glfwGetWindowSize(&width, &height);
        glViewport(0, 0, width, height);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // Mouse states
        unsigned char mousebutton = 0;
        int currentglfwscroll = glfwGetMouseWheel();
        int mscroll = 0;
        if (currentglfwscroll < glfwscroll)
            mscroll = 2;
         if (currentglfwscroll > glfwscroll)
            mscroll = -2;
        glfwscroll = currentglfwscroll;
        int mousex; int mousey;
        glfwGetMousePos(&mousex, &mousey);
        mousey = height - mousey;
        int leftButton = glfwGetMouseButton( GLFW_MOUSE_BUTTON_LEFT );
        int rightButton = glfwGetMouseButton( GLFW_MOUSE_BUTTON_RIGHT );
        int middleButton = glfwGetMouseButton( GLFW_MOUSE_BUTTON_MIDDLE );
        int toggle = 0;
        if( leftButton == GLFW_PRESS )
            mousebutton |= IMGUI_MBUT_LEFT;
    
        // Draw UI
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        float projection[16] = { 2.f/width, 0.f, 0.f,  0.f,
                                 0.f, 2.f/height,  0.f,  0.f,
                                 0.f,  0.f, -2.f, 0.f,
                                 -1.f, -1.f,  -1.f,  1.f };
        glLoadMatrixf(projection);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        glUseProgram(0);


        imguiBeginFrame(mousex, mousey, mousebutton, mscroll);

        imguiBeginScrollArea("Scroll area", 10, 10, width / 5, height - 20, &scrollarea1);
        imguiSeparatorLine();
        imguiSeparator();

        imguiButton("Button");
        imguiButton("Disabled button", false);
        imguiItem("Item");
        imguiItem("Disabled item", false);
        toggle = imguiCheck("Checkbox", checked1);
        if (toggle)
            checked1 = !checked1;
        toggle = imguiCheck("Disabled checkbox", checked2, false);
        if (toggle)
            checked2 = !checked2;
        toggle = imguiCollapse("Collapse", "subtext", checked3);
        if (checked3)
        {
            imguiIndent();
            imguiLabel("Collapsible element");
            imguiUnindent();
        }
        if (toggle)
            checked3 = !checked3;
        toggle = imguiCollapse("Disabled collapse", "subtext", checked4, false);
        if (toggle)
            checked4 = !checked4;
        imguiLabel("Label");
        imguiValue("Value");
        imguiSlider("Slider", &value1, 0.f, 100.f, 1.f);
        imguiSlider("Disabled slider", &value2, 0.f, 100.f, 1.f, false);
        imguiIndent();
        imguiLabel("Indented");
        imguiUnindent();
        imguiLabel("Unindented");

        imguiEndScrollArea();

        imguiBeginScrollArea("Scroll area", 20 + width / 5, 500, width / 5, height - 510, &scrollarea2);
        imguiSeparatorLine();
        imguiSeparator();
        for (int i = 0; i < 100; ++i)
            imguiLabel("A wall of text");

        imguiEndScrollArea();
        imguiEndFrame();

        imguiDrawText(30 + width / 5 * 2, height - 20, IMGUI_ALIGN_LEFT, "Free text",  imguiRGBA(32,192, 32,192));
        imguiDrawText(30 + width / 5 * 2 + 100, height - 40, IMGUI_ALIGN_RIGHT, "Free text",  imguiRGBA(32, 32, 192, 192));
        imguiDrawText(30 + width / 5 * 2 + 50, height - 60, IMGUI_ALIGN_CENTER, "Free text",  imguiRGBA(192, 32, 32,192));

        imguiDrawLine(30 + width / 5 * 2, height - 80, 30 + width / 5 * 2 + 100, height - 60, 1.f, imguiRGBA(32,192, 32,192));
        imguiDrawLine(30 + width / 5 * 2, height - 100, 30 + width / 5 * 2 + 100, height - 80, 2.f, imguiRGBA(32, 32, 192, 192));
        imguiDrawLine(30 + width / 5 * 2, height - 120, 30 + width / 5 * 2 + 100, height - 100, 3.f, imguiRGBA(192, 32, 32,192));

        imguiDrawRoundedRect(30 + width / 5 * 2, height - 240, 100, 100, 5.f, imguiRGBA(32,192, 32,192));
        imguiDrawRoundedRect(30 + width / 5 * 2, height - 350, 100, 100, 10.f, imguiRGBA(32, 32, 192, 192));
        imguiDrawRoundedRect(30 + width / 5 * 2, height - 470, 100, 100, 20.f, imguiRGBA(192, 32, 32,192));
        
        imguiDrawRect(30 + width / 5 * 2, height - 590, 100, 100, imguiRGBA(32, 192, 32, 192));
        imguiDrawRect(30 + width / 5 * 2, height - 710, 100, 100, imguiRGBA(32, 32, 192, 192));
        imguiDrawRect(30 + width / 5 * 2, height - 830, 100, 100, imguiRGBA(192, 32, 32,192));

        imguiRenderGLDraw(width, height); 

        // Check for errors
        GLenum err = glGetError();
        if(err != GL_NO_ERROR)
        {
            fprintf(stderr, "OpenGL Error : %s\n", gluErrorString(err));
        }

        // Swap buffers
        glfwSwapBuffers();

    } // Check if the ESC key was pressed or the window was closed
    while( glfwGetKey( GLFW_KEY_ESC ) != GLFW_PRESS &&
           glfwGetWindowParam( GLFW_OPENED ) );

    // Clean UI
    imguiRenderGLDestroy();

    // Close OpenGL window and terminate GLFW
    glfwTerminate();

    exit( EXIT_SUCCESS );
}