OpenGL - 在一个函数中加载多个纹理

Posted 2023-02-16

【中文标题】OpenGL - 在一个函数中加载多个纹理

【英文标题】：OpenGL - Load mutliple texures in one function

【发布时间】：2019-11-25 18:00:21

【问题描述】：

我已经用glutSolidCube() 构建了一个 15x15 的立方体网格。然后我有一个菜单处理程序，当我单击“开始游戏”时，将我使用的纹理加载到所有立方体，调用自定义 glutSolidCube 并在每个顶点声明之前有 glTexCoord2d，因为我们不能我认为后者的纹理。为了从图像上传纹理，我使用了STB_IMAGE_IMPLEMENTATION 实现，其中还包含一个头文件。函数loadTextureFromFile(const char *filename) 负责加载部分。

如何上传更多纹理（我想要更多 2 个，最好在同一个 loadTextureFromFile() 函数中）以及如何使用 glTexCoord2d() 处理每个纹理？

这是我的完整代码：

#include<iostream>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/gl.h>     // openGL header
#include <GL/glu.h>   // glut header
#include <GL/glut.h>   // glut header
#define STB_IMAGE_IMPLEMENTATION


/////////////////////////////////////Textures==============================================/////////////////////////////////////
#include "stb_image.h"
GLuint texture; //the array for our texture


void loadTextureFromFile(const char *filename)

    glClearColor(0.0, 0.0, 0.0, 0.0);
    //glShadeModel(GL_FLAT);
    //glEnable(GL_DEPTH_TEST);

    unsigned int texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    // set the texture wrapping/filtering options (on the currently bound texture object)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load and generate the texture
    int width, height, nrChannels;
    unsigned char *data = stbi_load("paper.bmp", &width, &height, &nrChannels, 0);
    if (data)
    
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        //glGenerateMipmap(GL_TEXTURE_2D);
    
    else
    
        std::cout << "Failed to load texture" << std::endl;
    
    stbi_image_free(data);


void FreeTexture(GLuint texture)

    glDeleteTextures(1, &texture);




/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////


static void
drawBox(GLfloat size, GLenum type)

    static GLfloat n[6][3] =
    
        -1.0, 0.0, 0.0,
        0.0, 1.0, 0.0,
        1.0, 0.0, 0.0,
        0.0, -1.0, 0.0,
        0.0, 0.0, 1.0,
        0.0, 0.0, -1.0
        ;

    static GLint faces[6][4] =
    
        0, 1, 2, 3,
            3, 2, 6, 7,
            7, 6, 5, 4,
        4, 5, 1, 0,
        5, 6, 2, 1,
        7, 4, 0, 3
    ;
    GLfloat v[8][3];
    GLint i;

    v[0][0] = v[1][0] = v[2][0] = v[3][0] = -size / 2;
    v[4][0] = v[5][0] = v[6][0] = v[7][0] = size / 2;
    v[0][1] = v[1][1] = v[4][1] = v[5][1] = -size / 2;
    v[2][1] = v[3][1] = v[6][1] = v[7][1] = size / 2;
    v[0][2] = v[3][2] = v[4][2] = v[7][2] = -size / 2;
    v[1][2] = v[2][2] = v[5][2] = v[6][2] = size / 2;

    for (i = 5; i >= 0; i--) 
        glBegin(type);
            glNormal3fv(&n[i][0]);

        glTexCoord2d(0.0,0.0);
            glVertex3fv(&v[faces[i][0]][0]);
        glTexCoord2d(0.0,1.0);
            glVertex3fv(&v[faces[i][1]][0]);
        glTexCoord2d(1.0,1.0);
            glVertex3fv(&v[faces[i][2]][0]);
        glTexCoord2d(1.0,0.0);
            glVertex3fv(&v[faces[i][3]][0]);
            glEnd();
    


void APIENTRY
myglutSolidCube(GLdouble size)

  drawBox(size, GL_QUADS);


//int red_color[]=255,0,0;
//int blue_colot[]=0,0,255;


//////////////////////////////=========MENU============/////////////
enum MENU_TYPE //menu options-values

        MENU_START,
        MENU_EXIT,

;

//create the menu - Prototype
void my_createmenu(void);
// Menu handling function declaration - Prototype
void menu(int);



void init()
       //for 3d lighting
    glEnable(GL_DEPTH_TEST); //depth test
    glEnable(GL_LIGHTING); //enable light from a single source
    glEnable(GL_LIGHT0); //enable white light , diffuse and specular components
    glEnable(GL_COLOR_MATERIAL); //track the current color




void display()





    glClearColor(0.0f, 0.0f, 0.0f, 1.0f); //Black and opaque
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    //define the projection matrix just once and use the modelview matrix all other times


    glMatrixMode(GL_PROJECTION);  //Applies subsequent matrix operations to the projection matrix stack
    glLoadIdentity();//Reset

    GLint viewport[4];
    glGetIntegerv(GL_VIEWPORT, viewport); //The params parameter returns four values: the x and y window coordinates of the viewport, followed by its width and height
    double aspect = (double)viewport[2] / (double)viewport[3]; // y/width would be 1.0

    gluPerspective(60,aspect, 1, 100); //using perspective projection
    //gluOrtho2D(0.0,600.0,-60.0,600.0);  


    glMatrixMode(GL_MODELVIEW); //for trasformations - Applies subsequent matrix operations to the texture matrix stack
    glLoadIdentity();

    // move back a bit for viewer  , cause of gluPerspective
    glTranslatef( 0, 0, -35 );


    float e=0,f=0;

    //construct the grid with reference the central cube  
    for(int i=0;i<8;i++) 
        for(int j=0;j<8;j++)       
            glPushMatrix();
                glTranslatef(0.0f+e,0.0f+f,0.0f); //right and below
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    glColor3ub(245, 245, 220); //Beige
                    glutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f-e,0.0f+f,0.0f); //left and below
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    glColor3ub(245, 245, 220); //Beige
                    glutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f+e,0.0f-f,0.0f); //right and up
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    glColor3ub(245, 245, 220); //Beige
                    glutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f-e,0.0f-f,0.0f); //left and up
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    glColor3ub(245, 245, 220); //Beige
                    glutSolidCube(2.25);
                glPopMatrix();


                f += -2.63;
            
            f=0;
            e+=2.63;
        





    glutSwapBuffers(); //implicit   glFlush





//for the second part of program 
void display_game()





    glClearColor(0.0f, 0.0f, 0.0f, 1.0f); //Black and opaque
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    //define the projection matrix just once and use the modelview matrix all other times

    glMatrixMode(GL_PROJECTION);  //Applies subsequent matrix operations to the projection matrix stack
    glLoadIdentity();//Reset

    GLint viewport[4];
    glGetIntegerv(GL_VIEWPORT, viewport); //The params parameter returns four values: the x and y window coordinates of the viewport, followed by its width and height
    double aspect = (double)viewport[2] / (double)viewport[3]; // y/width would be 1.0


    gluPerspective(60,aspect, 1, 100); //using perspective projection
    //glOrtho(0.0f, 600.0f, 600.0f, 0.0f, 0.0f, 1.0f);


    glMatrixMode(GL_MODELVIEW); //for trasformations - Applies subsequent matrix operations to the texture matrix stack
    glLoadIdentity();

    // move back a bit for viewer  , cause of gluPerspective
    glTranslatef( 0, 0, -35 );


    float e=0,f=0;



    glEnable(GL_TEXTURE_2D);

    //construct the grid with reference the central cube  
    for(int i=0;i<8;i++) 
        for(int j=0;j<8;j++)       
            glPushMatrix();
                glTranslatef(0.0f+e,0.0f+f,0.0f); //right and below
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    //glColor3ub(245, 245, 220); //Beige
                //glColor3ub( rand()%255,rand()%255, rand()%255 );
                    myglutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f-e,0.0f+f,0.0f); //left and below
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    //glColor3ub( rand()%255,rand()%255, rand()%255 );
                    myglutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f+e,0.0f-f,0.0f); //right and up
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    myglutSolidCube(2.25);
                glPopMatrix();

            glPushMatrix();
                glTranslatef(0.0f-e,0.0f-f,0.0f); //left and up
                glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                    myglutSolidCube(2.25);
                glPopMatrix();


                f += -2.63;
            
            f=0;
            e+=2.63;
        


    //SEED to some constant value for 2nd part of the program. If it is not used , cubes would change color in runtime
    //srand(0x98765432); 


    glutSwapBuffers(); //implicit   glFlush


    glDisable(GL_TEXTURE_2D);


void reshape(GLsizei width, GLsizei height)  

    // GLsizei for non-negative integer // Compute aspect ratio of the new window

    if (height == 0) height = 1; // To prevent divide by 0 
    GLfloat aspect = (GLfloat)width / (GLfloat)height; // Set the viewport to cover the new window 
    glViewport(0, 0, width, height); // Set the aspect ratio of the clipping volume                 glMatrixMode(GL_PROJECTION); // To operate on the Projection matrix 
    glLoadIdentity(); // Reset // Enable perspective projection with fovy, aspect, zNear and zFar 
    gluPerspective(45.0f, aspect, 0.1f, 100.0f); 

 

void timer(int extra)

    glutPostRedisplay();
    glutTimerFunc(16, timer, 0);



void mouseEscape( int button, int state, int x, int y )

    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN &&button==MENU_EXIT)

    
        int windowID = glutCreateWindow("CUBES");
        glutDestroyWindow(windowID);
        exit(0);
    

            glutPostRedisplay();



//for loading the texture
const char* filename = "salt_on_spoon.bmp";
int main(int argc, char **argv)

    glutInit(&argc, argv);
        glutInitWindowSize(600,600);
        glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE| GLUT_MULTISAMPLE);
        glEnable(GL_MULTISAMPLE); //anti-alliasing  
    glutCreateWindow("CUBES");



    //create and handle the menu
    my_createmenu();

    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutTimerFunc(0, timer, 0);


        init();
    //glEnable(GL_TEXTURE_2D); //for texture
    //glutMouseFunc(mouseEscape);
    //glutKeyboardFunc(keyEscape);

    //Load our texture
    //loadTextureFromFile(filename);



    glutMainLoop();

    //Free our texture
    //FreeTexture(texture);

    return 0;


//create the menu-entries
void my_createmenu(void) 

    // Create a menu
        glutCreateMenu(menu);

        // Add menu items
        glutAddMenuEntry("Start Game", MENU_START);
        glutAddMenuEntry("Exit", MENU_EXIT);

        // Associate a mouse button with menu
        glutAttachMenu(GLUT_RIGHT_BUTTON);




// Menu handling function-what to do in each value
void menu(int item)

        switch (item)
        
        case MENU_START: 

        //glEnable(GL_TEXTURE_2D); //for texture

        //Load our texture
        loadTextureFromFile(filename);

        glutDisplayFunc(display_game);
        
        break;
        case MENU_EXIT: 
        
        int windowID = glutCreateWindow("CUBES"); //exit game
        glutDestroyWindow(windowID);
        exit(0);                
            
                break;  
        default:
                       /* Nothing */       
                break;
        

        glutPostRedisplay();

        return;

我正在菜单功能中进行纹理加载部分。我将如何处理三种纹理？最终目标是同时调用要在立方体上渲染的三个纹理。

我还有两张图：第一张：节目开始的时候：

第二个：点击“星际游戏”后，您可以看到所有立方体中渲染的纹理：

目标是更多 2 种类型的纹理，并且所有这些纹理都呈现在随机立方体中。

【参考方案1】：

您可以创建多个纹理对象。 glBindTexture 将命名纹理绑定到纹理目标，即全局状态。 glTexImage2D为纹理指定二维纹理图像，当前绑定到指定目标。 glTexParameter给纹理对象设置参数。

我建议编写一个函数，将文件中的纹理加载到给定的纹理对象（名称 id）：

void loadTextureFromFile(const char *filename, unsigned int texture)

    glBindTexture(GL_TEXTURE_2D, texture);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load and generate the texture
    int width, height, nrChannels;
    unsigned char *data = stbi_load(filename, &width, &height, &nrChannels, 0);
    if (data)
    
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0,
                     GL_RGB, GL_UNSIGNED_BYTE, data);
        //glGenerateMipmap(GL_TEXTURE_2D);
    
    else
    
        std::cout << "Failed to load texture" << std::endl;
    
    stbi_image_free(data);


const char* filename1 = "salt_on_spoon.bmp";
const char* filename2 = ...;
const char* filename3 = ...;
unsigned int tob[3];

int main(int argc, char **argv)

    // [...]

    glGenTextures(3, &tob[0]);

    loadTextureFromFile(filename1, tob[0]);
    loadTextureFromFile(filename2, tob[1]);
    loadTextureFromFile(filename3, tob[2]);

    // [...]

启用二维纹理后，当前绑定到目标GL_TEXTURE_2D 的纹理对象的图像将包裹在网格上。

在绘制几何图形之前，您必须绑定正确的纹理对象。例如：

for(int i=0;i<8;i++) 
    for(int j=0;j<8;j++) 

        glBindTexture(GL_TEXTURE_2D, tob[0]);
        glPushMatrix();
            glTranslatef(0.0f+e,0.0f+f,0.0f); //right and below
            glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                myglutSolidCube(2.25);
        glPopMatrix();

        glBindTexture(GL_TEXTURE_2D, tob[1]);
        glPushMatrix();
            glTranslatef(0.0f-e,0.0f+f,0.0f); //left and below
            glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                myglutSolidCube(2.25);
        glPopMatrix();

        glBindTexture(GL_TEXTURE_2D, tob[2]);
        glPushMatrix();
            glTranslatef(0.0f+e,0.0f-f,0.0f); //right and up
            glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                myglutSolidCube(2.25);
        glPopMatrix();

        glBindTexture(GL_TEXTURE_2D, tob[0]);
        glPushMatrix();
            glTranslatef(0.0f-e,0.0f-f,0.0f); //left and up
            glRotatef(20.0f,1.0f,-2.0f,0.0f); //looking 3d
                myglutSolidCube(2.25);
        glPopMatrix();

        f += -2.63;
    
    f=0;
    e+=2.63;

注意，纹理的分布只是一个例子。您必须确保 unsigned int tob[3]; 之前在全局命名空间中声明。

【讨论】：

也是 main 中的部分，glGenTextures(3, &tob);应该类似于 glGenTextures(3, &tob[3]);对吧？

我收到一个错误：错误：无法将参数 '2' 的 'unsigned int ()[3]' 转换为 'GLuint aka unsigned int*' void glGenTextures(GLsizei, GLuint*)' glGenTextures(3, &tob);我使用的编译参数是： g++ -fpcc-struct-return -I/usr/include -g main.cpp -L/usr/lib/ -lGLU -lGL -lglut -lm -o main

@DavidDunn 它必须是glGenTextures(3, &tob[0]);（第一个数组元素的地址）。但是glGenTextures(3, tob); 也应该可以工作。