用Modern OpenGL渲染我的第一个三角形

Rendering my first triangle with Modern OpenGL

本文关键字:我的 第一个 三角形 Modern OpenGL      更新时间:2023-10-16

我想使用现代OpenGL来渲染我的第一个三角形。(我正在使用SFML(我有2节课:

global

,我使用它来初始化全局 sfml 变量等(与我的问题无关(

#ifndef GLOBAL_H
#define GLOBAL_H
#include <SFML/OpenGL.hpp>
#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>
#include <glm/glm.hpp>
using namespace std;
extern sf::Event Event;
extern sf::Shader defaultShader;
extern sf::ContextSettings settings;
extern sf::Window window;
void initShader();
#endif // GLOBAL_H

Model

这将加载一个 obj 文件加载器。我使用Blender生成了它。是这样的:

#ifndef MODEL_H
#define MODEL_H
#include <GL/glew.h>
#include "global.h"
struct Vertex{
    float x,y,z;
    Vertex(){};
    Vertex(float a,float b,float c){x=a;y=b;z=c;};
};
struct TextureCoordinate{
    float x;
    float y;
    TextureCoordinate(){};
    TextureCoordinate(float a,float b){x=a;y=b;};
};
struct FaceTexture{
    string texture;
    int vertex[3];
};
class Model
{
    public:
        Model();
        vector<Vertex> vertices;
        vector<FaceTexture> faces;
        vector<TextureCoordinate> textureCoordinates;
        vector<Vertex> normals;
        void loadModel(const char *fileName);
        void setupMesh();
        void draw();
    private:
        GLuint VAO, VBO;
};
#endif // MODEL_H

和CPP:

#include "Model.h"
Model::Model()
{
}
void Model::loadModel(const char *fileName)
{
    int i;
    vector<string>line;
    vector<string>tmp;
    vector<int>V1;vector<int>V2;vector<int>V3;vector<int>T1;vector<int>T2;vector<int>T3;vector<int>N1;vector<int>N2;vector<int>N3;
    vector<TextureCoordinate>tc;
    vector<Vertex>nc;
    ifstream fin(fileName);
    char aux[200],matFileName[200];
    float v1,v2,v3,t1,t2,t3,n1,n2,n3;
    while(!fin.eof())
    {
        fin.getline(aux,256);
        line.push_back(aux);
    }
    fin.close();
    sscanf(line[2].c_str(),"mtllib %s",&matFileName);
    fin.open(("models/"+string("matFileName")).c_str());
    while(!fin.eof())
    {
        fin.getline(aux,200);
        tmp.push_back(aux);
    }
    ///***///
    for(i=3;i<line.size();i++)
    {
        char matName[100];
        if(line[i][0]=='v'&& line[i][1]==' ')
        {
            Vertex v;
            sscanf(line[i].c_str(),"v %f %f %f",&v.x,&v.y,&v.z);
            vertices.push_back(v);
            continue;
        }
        if(line[i][0]=='v'&&line[i][1]=='t')
        {
            TextureCoordinate t;
            sscanf(line[i].c_str(),"vt %f %f",&t.x,&t.y);
            textureCoordinates.push_back(t);
            continue;
        }
        if(line[i][0]=='v'&&line[i][1]=='n')
        {
            Vertex v;
            sscanf(line[i].c_str(),"vn %f %f %f",&v.x,&v.y,&v.z);
            normals.push_back(v);
            continue;
        }
        if(line[i][0]=='u'&&line[i][1]=='s'&&line[i][2]=='e')
        {
            sscanf(line[i].c_str(),"usemtl %s",&matName);
            continue;
        }
        if(line[i][0]=='f'&&line[i][1]==' ')
        {
            FaceTexture f;
            sscanf(line[i].c_str(),"f %d/%d/%d %d/%d/%d %d/%d/%d ",&v1,&v2,&v3,&t1,&t2,&t3,&n1,&n2,&n3);
            f.texture=matName;
            faces.push_back(f);
            V1.push_back(v1);V2.push_back(v2);V3.push_back(v3);
            T1.push_back(t1);T2.push_back(t2);T3.push_back(t3);
            N1.push_back(n1);N2.push_back(n2);N3.push_back(n3);
            continue;
        }
    }
    tc.resize(vertices.size());
    nc.resize(vertices.size());
    textureCoordinates.resize(vertices.size());
    normals.resize(vertices.size());
    for(i=0;i<faces.size();i++)
    {
        tc[V1[i]]=textureCoordinates[T1[i]];
        nc[V1[i]]=normals[N1[i]];
        tc[V2[i]]=textureCoordinates[T2[i]];
        nc[V2[i]]=normals[N2[i]];
        tc[V3[i]]=textureCoordinates[T3[i]];
        nc[V3[i]]=normals[N3[i]];
    }
    for(i=0;i<vertices.size();i++)
    {
        textureCoordinates[i]=tc[i];
        normals[i]=nc[i];
    }
    for(i=0;i<faces.size();i++)
    {
        faces[i].vertex[0]=V1[i];
        faces[i].vertex[1]=V2[i];
        faces[i].vertex[2]=V3[i];
    }
    setupMesh();
}
void Model::setupMesh()
    {
        glGenBuffers(1, & VBO);
        glBindVertexArray(VAO);
        glBindBuffer(GL_ARRAY_BUFFER,  VBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), &vertices[0], GL_STATIC_DRAW);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);
        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindVertexArray(0);
    }
void Model::draw()
{
    glBindVertexArray(VAO);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    glBindVertexArray(0);
}

顶点着色器:

#version 330 core
layout (location = 0) in vec3 position;
//layout (location = 1) in vec3 color;
out vec3 ourColor;
void main()
{
    ourColor=vec3(1,0,0);
    gl_Position = vec4(position, 1.0f);
    //ourColor = color;
}

和碎片着色器:

#version 330 core
in vec3 ourColor;
out vec4 color;
void main()
{
    color = vec4(ourColor, 1.0f);
}

主.cpp:

#include <GL/glew.h>
#include <global.h>
#include "Model.h"
using namespace std;
Model model;
int main()
{
    glewInit();
    initShader();
    glEnable(GL_DEPTH_TEST);
    model.loadModel("models/1/cube.obj");
    sf::Shader::bind(&defaultShader);
    while (window.isOpen())
    {
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
        while (window.pollEvent(Event))
        {
            if (Event.type == sf::Event::Closed)
                window.close();
        }
        model.draw();
        window.display();
    }
    return 0;
}

为什么程序显示黑屏?当我使用旧函数时,该程序运行良好(glBegin,glEnd(

您可以使用变量VAO而不对其进行初始化或创建 VAO。你将不得不打电话

glGenVertexArrays(1, &VAO);

以获取有效的顶点数组。

编辑 1

下一个问题:推送到 VBO 的数据大小错误

glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), &vertices[0], GL_STATIC_DRAW);

在这种情况下,sizeof(vertices)等于sizeof(vector<Vertex>)这是矢量对象在内存中的大小,而不是矢量数据的大小。你想要的是

glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertices.size(), &vertices[0], GL_STATIC_DRAW);