stuff-from-scratch/src/graphics/opengl/OpenGlPainter.cpp

#include "OpenGlPainter.h"

#include "DrawingContext.h"
#include "DrawingSurface.h"
#include "Scene.h"
#include "TriMesh.h"

#include "FontsManager.h"
#include "FontGlyph.h"

#include "OpenGlFontTexture.h"
#include "OpenGlShaderProgram.h"
#include "TextData.h"

#include "File.h"

#ifdef _WIN32
#include <windows.h>
#endif

#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glx.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <iostream>

OpenGlPainter::OpenGlPainter()
{

}

void OpenGlPainter::initializeMeshShader()
{
    if (auto context = glXGetCurrentContext())
    {
        std::cout << "has valid context" << std::endl;
    }
    else
    {
        std::cout << "no valid context" << std::endl;
    }

    int major_version{0};
    int minor_version{0};
    glGetIntegerv(GL_MAJOR_VERSION, &major_version);
    glGetIntegerv(GL_MINOR_VERSION, &minor_version);
    std::cout << "Using opengl version " << major_version << "|" << minor_version << std::endl;

    auto vert_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/default.vert";
    auto frag_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/default.frag";

    mMeshShaderProgram = std::make_unique<OpenGlShaderProgram>(vert_shader_path, frag_shader_path);
}

void OpenGlPainter::initializeTextShader()
{
    auto vert_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/text.vert";
    auto frag_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/text.frag";

    mTextShaderProgram = std::make_unique<OpenGlShaderProgram>(vert_shader_path, frag_shader_path);
}

void OpenGlPainter::renderTextLayer(const TextData& textData, DrawingContext* context)
{
    if (!mTextShaderProgram)
    {
        initializeTextShader();
    }

    auto first_char = textData.mContent[0];
    auto iter = mFontTextures.find(first_char);
    OpenGlFontTexture* working_texture{nullptr};
    if (iter == mFontTextures.end())
    {
        auto glyph = context->getFontsManager()->getGlyph(first_char);
        auto new_texture = std::make_unique<OpenGlFontTexture>(nullptr);
        working_texture = new_texture.get();
        mFontTextures[first_char] = std::move(new_texture);
    }
    else
    {
        working_texture = iter->second.get();
    }

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}

void OpenGlPainter::renderMeshLayer(TriMesh* mesh, DrawingContext* context)
{
    if (!mMeshShaderProgram)
    {
        initializeMeshShader();
    }

    float vertices[] = {
         0.5f,  0.5f, 0.0f,  // top right
         0.5f, -0.5f, 0.0f,  // bottom right
        -0.5f, -0.5f, 0.0f,  // bottom left
        -0.5f,  0.5f, 0.0f   // top left
    };

    unsigned int indices[] = {  // note that we start from 0!
        0, 1, 3,   // first triangle
        1, 2, 3    // second triangle
    };
    unsigned int vbo{0};
    glGenBuffers(1, &vbo);

    unsigned int EBO;
    glGenBuffers(1, &EBO);

    unsigned int VAO;
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    int vertexColorLocation = glGetUniformLocation(mMeshShaderProgram->getHandle(), "ourColor");

    glUseProgram(mMeshShaderProgram->getHandle());
    glBindVertexArray(VAO);

    glUniform4f(vertexColorLocation, 0.0f, 1.0, 0.0f, 1.0f);

    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);
    /*
    std::cout << "Bounds are : " << width << " | " << height << std::endl;

    for (std::size_t idx=0; idx<num_mesh; idx++)
    {
        auto mesh = context->getScene()->getMesh(idx);
        const auto faces =  mesh->getFaceVertices();
        const auto colors = mesh->getFaceVectorAttributes("Color");

        std::size_t counter{0};
        for (const auto& face : faces)
        {
            const auto r = colors[counter][0];
            const auto g = colors[counter][1];
            const auto b = colors[counter][2];

            glColor3f(r, g, b);

            glBegin(GL_TRIANGLES);
            double x0 = 2.0*face[0].getX()/width - 1.0;
            double y0 = 1.0 - 2.0*face[0].getY()/height;

            double x1 = 2.0*face[1].getX()/width - 1.0;
            double y1 = 1.0 - 2.0*face[1].getY()/height;

            double x2 = 2.0*face[2].getX()/width - 1.0;
            double y2 = 1.0 - 2.0*face[2].getY()/height;

            glVertex3f(x0, y0, 0);
            glVertex3f(x1, y1, 0);
            glVertex3f(x2, y2, 0);

            std::cout << "Verts0| " << x0 << " | " << y0 << " | "<< std::endl;
            std::cout << "Verts1| " << x1 << " | " << y1 << " | "<< std::endl;
            std::cout << "Verts2| " << x2 << " | " << y2 << " | "<< std::endl;
            std::cout << "****************" << std::endl;

            glEnd();

            counter++;
            break;
        }
        break;
    }
    */
}

void OpenGlPainter::paint(DrawingContext* context)
{
    auto surface = context->getSurface();
    const auto width = double(surface->getWidth());
    const auto height = double(surface->getHeight());

    glViewport(0, 0, width, height);
    //glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
    //glScissor(0, 0, width, height);
    //glMatrixMode(GL_PROJECTION);
    //glLoadIdentity();

    glClearColor(0.5, 0.5, 1.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);

    //glMatrixMode(GL_MODELVIEW);
   //glLoadIdentity();

    const auto num_mesh = context->getScene()->getNumMeshes();
    //renderMeshLayer(nullptr, context);

    auto text_data = context->getScene()->getTextData();
    renderTextLayer(text_data[0], context);

    glFlush();
}