cube-game-plus-plus/engine/Mesh.cpp

#include "Mesh.h"
#include <cstring>
#include <iostream>

using namespace std;

Mesh::Mesh(int mode)
{
    // position
    positionStartIndex = vertexSize;
    vertexSize += 3;
    
    // color
    if(mode & COLOR)
    {
        colorStartIndex = vertexSize;
        vertexSize += 4;
    }
    
    // texture
    if(mode & TEXTURE)
    {
        textureStartIndex = vertexSize;
        vertexSize += 2;
    }
    
    // normal
    if(mode & NORMAL)
    {
        normalStartIndex = vertexSize;
        vertexSize += 3;
    }
    
    data = new float[dataSize * vertexSize];
    
    glGenVertexArrays(1, &vba);
    glBindVertexArray(vba);
    
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);

    glVertexAttribPointer(0, 3, GL_FLOAT, 0, sizeof(float) * vertexSize, (GLvoid*) (sizeof(float) * positionStartIndex));
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 4, GL_FLOAT, 0, sizeof(float) * vertexSize, (GLvoid*) (sizeof(float) * colorStartIndex));
    glEnableVertexAttribArray(1);     
    
    glVertexAttribPointer(2, 2, GL_FLOAT, 0, sizeof(float) * vertexSize, (GLvoid*) (sizeof(float) * textureStartIndex));
    glEnableVertexAttribArray(2);  
    
    glVertexAttribPointer(3, 3, GL_FLOAT, 0, sizeof(float) * vertexSize, (GLvoid*) (sizeof(float) * normalStartIndex));
    glEnableVertexAttribArray(3);
}

Mesh::~Mesh()
{
    delete[] data;
    glDeleteVertexArrays(1, &vba);
    glDeleteBuffers(1, &vbo);
}

void Mesh::ensureCapacity(unsigned int index)
{
    if(index >= dataSize)
    {
        float* newData = new float[dataSize * 2 * vertexSize];
        memcpy(newData, data, sizeof(float) * dataSize * vertexSize);
        delete[] data;
        data = newData;
        dataSize *= 2;
    }
}

void Mesh::addPosition(float x, float y, float z)
{
    ensureCapacity(positionIndex);
    unsigned int index = positionStartIndex +  positionIndex * vertexSize;
    data[index] = x;
    data[index + 1] = y;
    data[index + 2] = z;
    positionIndex++;
}

void Mesh::addColor(float r, float g, float b, float a)
{
    ensureCapacity(colorIndex);
    unsigned int index = colorStartIndex +  colorIndex * vertexSize;
    data[index] = r;
    data[index + 1] = g;
    data[index + 2] = b;
    data[index + 3] = a;
    colorIndex++;
}

void Mesh::addTexture(float tx, float ty)
{
    ensureCapacity(textureIndex);
    unsigned int index = textureStartIndex +  textureIndex * vertexSize;
    data[index] = tx;
    data[index + 1] = ty;
    textureIndex++;
}

void Mesh::addNormal(float nx, float ny, float nz)
{
    ensureCapacity(normalIndex);
    unsigned int index = normalStartIndex +  normalIndex * vertexSize;
    data[index] = nx;
    data[index + 1] = ny;
    data[index + 2] = nz;
    normalIndex++;
}

void Mesh::build(bool print)
{
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
   
    vertices = positionIndex;
    
    if(print)
    {
        cout << "______________" << vertices << " " << vertexSize << endl;
        for(int i = 0; i < vertices; i++)
        {
            cout << "----------vert " << i << endl;
            int index = i * vertexSize;
            for(int j = 0; j < vertexSize; j++)
            {
                cout << data[index + j] << " " << endl;
            }
        }
    }
    
    glBufferData(GL_ARRAY_BUFFER, sizeof(float) * vertexSize * vertices, data, GL_STATIC_DRAW);
    
    positionIndex = 0;
    colorIndex = 0;
    textureIndex = 0;
    normalIndex = 0;
}

void Mesh::draw()
{
    if(vertices == 0)
    {
        return;
    }
    glBindVertexArray(vba);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glDrawArrays(GL_TRIANGLES, 0, vertices);
}

void Mesh::draw(int start, int count)
{
    if(vertices == 0 || start < 0 || start >= vertices || start + count > vertices)
    {
        return;
    }
    glBindVertexArray(vba);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glDrawArrays(GL_TRIANGLES, start, count);
}