与GLSL相关的OpenGL应用程序代码

我很难理解OpenGL应用程序和GLSL文件（.vert和.frag）之间的连接。我知道如何创建顶点或片段着色器，网上有很多例子，但我很难在应用程序中实际使用着色器，特别是将纹理链接（绑定？）到着色器。我的问题是，我缺少什么代码来使用我上传到应用程序中的纹理和着色器？

我当前的应用程序创建一个窗口，加载4个纹理（岩石、草、石头和混合贴图，因为我想使用它来进行纹理飞溅），然后在主循环中绘制一个四边形。我的整个应用程序代码如下：

#include <windows.h>
#include <iostream>
#include <sstream>
#include <fstream>
#include <SFML/Graphics.hpp>
#include <glew.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include "textfile.h"
#include "textfile.cpp"
using namespace std;
class Scene {
public:
    void resize( int w, int h ) {
        // OpenGL Reshape
        glViewport( 0, 0, w, h );
        glMatrixMode( GL_PROJECTION );
        glLoadIdentity();
        gluPerspective( 120.0, (GLdouble)w/(GLdouble)h, 0.5, 500.0 );
        glMatrixMode( GL_MODELVIEW );
    }
};
///Shader
GLuint p, f, v;
void setShader() {
    char *vs,*fs;
    v = glCreateShader(GL_VERTEX_SHADER);
    f = glCreateShader(GL_FRAGMENT_SHADER);
    vs = textFileRead("shader.vert");
    fs = textFileRead("shader.frag");
    const char * vv = vs;
    const char * ff = fs;
    glShaderSource(v, 1, &vv,NULL);
    glShaderSource(f, 1, &ff,NULL);
    free(vs);free(fs);
    glCompileShader(v);
    glCompileShader(f);
    p = glCreateProgram();
    glAttachShader(p,v);
    glAttachShader(p,f);
    glLinkProgram(p);
    glUseProgram(p);
}
int main() {
    sf::RenderWindow window(sf::VideoMode(800, 600, 32), "Test");
    ///Setup the scene, materials, lighting
    Scene scene;
    scene.resize(800,600);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glColorMaterial(GL_FRONT_AND_BACK, GL_EMISSION);
    glEnable(GL_COLOR_MATERIAL);
    glShadeModel(GL_SMOOTH);
    ///Terrain Textures
    sf::Image tex0;
    tex0.loadFromFile("mixmap.png");
    sf::Image tex1;
    tex1.loadFromFile("grass.png");
    sf::Image tex2;
    tex2.loadFromFile("rock.png");
    sf::Image tex3;
    tex3.loadFromFile("stone.png");
    GLuint mixmap;
    glGenTextures(1, &mixmap);
    glBindTexture(GL_TEXTURE_2D, mixmap);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex0.getSize().x, tex0.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex0.getPixelsPtr() );
    GLuint grass;
    glGenTextures(1, &grass);
    glBindTexture(GL_TEXTURE_2D, grass);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex1.getSize().x, tex1.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex1.getPixelsPtr() );
    GLuint rock;
    glGenTextures(1, &rock);
    glBindTexture(GL_TEXTURE_2D, rock);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex2.getSize().x, tex2.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex2.getPixelsPtr() );
    GLuint stone;
    glGenTextures(1, &stone);
    glBindTexture(GL_TEXTURE_2D, stone);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex3.getSize().x, tex3.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex3.getPixelsPtr() );
    ///I am afrain I am missing some code here that will actually link the textures to the shader itself
    ///Shader
    glewInit();
    setShader();
    ///Start loop
    while( window.isOpen() ) {
        sf::Event event;
        while( window.pollEvent( event ) ) {
            if( event.type == sf::Event::Closed )
                window.close();
        }
        glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        gluPerspective(50.0, 1.0, 1.0, 50);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(1, 0, 1, 0, 0, 0, 0, 1, 0);
        glBegin(GL_QUADS);
            glVertex3f(-0.5, -0.5, 0.0);
            glVertex3f(-0.5, 0.5, 0.0);
            glVertex3f(0.5, 0.5, 0.0);
            glVertex3f(0.5, -0.5, 0.0);
        glEnd();
        ///Reset env settings for SFML
        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
        window.display();
    }
    return 1;
}

下面是我的顶点和片段着色器，尽管我不确定我的顶点着色器是否完整。。。

顶点：

void main()
{
 gl_TexCoord[0] = gl_MultiTexCoord0;
 gl_Position = ftransform();
} 

片段：

uniform sampler2D MixMap;
uniform sampler2D Grass;
uniform sampler2D Stone;
uniform sampler2D Rock;
varying vec4 texCoord;
void main(void)
{
   vec4 mixmap   = texture2D( MixMap, texCoord.xy );
   vec4 tex0    = texture2D( Grass, texCoord.xy ); 
   vec4 tex1    = texture2D( Rock,  texCoord.xy ); 
   vec4 tex2    = texture2D( Stone, texCoord.xy );
   tex0 *= mixmap.r; 
   tex1 = mix( tex0, tex1, mixmap.g ); 
   vec4 outColor = mix( tex1, tex2, mixmap.b ); 
   gl_FragColor = outColor;
}