Coord纹理数组不适用于多维数据集

Question

我的程序的目的是加载和显示每个面上具有相同纹理的简单立方体。问题是2个第一面（前面，后面）都很好。我在纹理数组中尝试了几种顶点组合，但它不起作用。我不知道是否需要在纹理数组中添加更多顶点或更改顺序或更改索引数组。

#define OFFSET_BUFFER(bytes) ((GLfloat *)NULL + bytes)

float vertices[] =
{
    -1.0f, -1.0f, 1.0f, // 0 
    1.0f, -1.0f, 1.0f,  // 1 
    -1.0f, 1.0f, 1.0f,  // 2 
    1.0f, 1.0f, 1.0f,   // 3 

    -1.0f, -1.0f, -1.0f,// 4 
    1.0f, -1.0f, -1.0f, // 5 
    -1.0f, 1.0f, -1.0f, // 6 
    1.0f, 1.0f, -1.0f,  // 7 
}; 

GLubyte indices[] =
{
    0,1,2, 1,3,2, //front face
    6,7,5, 6,5,4, //rear face
    1,5,3, 5,7,3, //problem on the right face
    //2,3,6, 3,6,7,
    //2,4,0, 2,4,6
    0,5,1, 5,4,0
}; 

float textures[] =
{
    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3
}; 

int main(int argc, char *argv[])
{
    SDL_Init(SDL_INIT_VIDEO);
    SDL_WM_SetCaption("Texture Mapping",NULL);
    SDL_SetVideoMode(500, 500, 32, SDL_OPENGL);

    bool continuer = true;
    SDL_Event event;
    GLuint texCube;

    glClearDepth(1.0f);
    glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
    glEnable(GL_DEPTH_TEST);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(70.0f, (float)500.0f / (float)500.0f, 1.0f, 3000.0f);
    glewInit();

    texCube = loadTexture("caisse.jpg");
    glBindTexture(GL_TEXTURE_2D, texCube);

    glEnable(GL_TEXTURE_2D);

    while (continuer)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        SDL_WaitEvent(&event);
        switch(event.type)
        {
            case SDL_QUIT:
                continuer = false;
        }

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        gluLookAt(0.0f, 0.0f, 3.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

        //Draw Cube ---------------------------------------

        glPushMatrix();
        glRotatef(90.0f, 1.0f, 1.0f, 0.0f);

        glEnableClientState(GL_VERTEX_ARRAY);
        glVertexPointer(3, GL_FLOAT, 0, vertices);

        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer(2, GL_FLOAT, 0, textures);

        glDrawElements(GL_TRIANGLES, 24, GL_UNSIGNED_BYTE, indices);

        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);

        //-------------------------------------------------

        glPopMatrix();

        glFlush();
        SDL_GL_SwapBuffers();
    }

    glDisable(GL_TEXTURE_2D);
    SDL_Quit();

    return 0;
}

Answer 1

你的角落正在共享纹理坐标，这是不可行的。 每个面应该有4个顶点，因为每个角的纹理坐标会因面部而异。

Answer 2

我的问题的解决方案是以下代码：

#define OFFSET_BUFFER(bytes) ((GLfloat *)NULL + bytes)

float angle = 0.0f;

float vertices[72] =
{
    -1.0f, -1.0f, 1.0f,//VO - 0
    1.0f, -1.0f, 1.0f,//V1 - 1
    -1.0f, 1.0f, 1.0f,//V2 - 2
    1.0f, 1.0f, 1.0f,//V3 - 3

    -1.0f, -1.0f, -1.0f,//V4 - 4
    1.0f, -1.0f, -1.0f,//V5 - 5
    -1.0f, 1.0f, -1.0f,//V6 - 6
    1.0f, 1.0f, -1.0f,//V7 - 7

    -1.0f, 1.0f, 1.0f,//V2 - 8
    1.0f, 1.0f, 1.0f,//V3 - 9
    -1.0f, 1.0f, -1.0f,//V6 - 10
    1.0f, 1.0f, -1.0f,//V7 - 11

    -1.0f, -1.0f, 1.0f,//VO - 12
    1.0f, -1.0f, 1.0f,//V1 - 13
    -1.0f, -1.0f, -1.0f,//V4 - 14
    1.0f, -1.0f, -1.0f,//V5 - 15

    -1.0f, -1.0f, 1.0f,//VO - 16
    -1.0f, 1.0f, 1.0f,//V2 - 17
    -1.0f, -1.0f, -1.0f,//V4 - 18
    -1.0f, 1.0f, -1.0f,//V6 - 19

    1.0f, -1.0f, 1.0f,//V1 - 20
    1.0f, 1.0f, 1.0f,//V3 - 21
    1.0f, -1.0f, -1.0f,//V5 - 22
    1.0f, 1.0f, -1.0f,//V7 - 23
}; 

GLubyte indices[36] =
{
    0,1,2, 1,3,2,
    6,7,5, 6,5,4,
    8,9,10, 9,10,11,
    12,13,14, 13,14,15,
    17,16,18, 17,18,19,
    20,21,22, 21,22,23
}; 

float textures[48] =
{
    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3
}; 

int main(int argc, char *argv[])
{
    SDL_Init(SDL_INIT_VIDEO);
    SDL_WM_SetCaption("Texture Mapping",NULL);
    SDL_SetVideoMode(500, 500, 32, SDL_OPENGL);

    bool continuer = true;
    SDL_Event event;
    GLuint texCube;

    glClearDepth(1.0f);
    glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
    glEnable(GL_DEPTH_TEST);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(70.0f, (float)500.0f / (float)500.0f, 1.0f, 3000.0f);
    glewInit();

    texCube = loadTexture("caisse.jpg");
    glBindTexture(GL_TEXTURE_2D, texCube);

    glEnable(GL_TEXTURE_2D);

    while (continuer)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        SDL_WaitEvent(&event);
        switch(event.type)
        {
            case SDL_QUIT:
                continuer = false;
        }

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        gluLookAt(0.0f, 0.0f, 3.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

        //Draw Cube ---------------------------------------

        glPushMatrix();
        glRotatef(angle, 1.0f, 1.0f, 0.0f);

        glEnableClientState(GL_VERTEX_ARRAY);
        glVertexPointer(3, GL_FLOAT, 0, vertices);

        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer(2, GL_FLOAT, 0, textures);

        glDrawElements(GL_TRIANGLES, 48, GL_UNSIGNED_BYTE, indices);

        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);

        //-------------------------------------------------

        angle += 1.0f;

        glPopMatrix();

        glFlush();
        SDL_GL_SwapBuffers();
    }

    glDisable(GL_TEXTURE_2D);
    SDL_Quit();

    return 0;
}

Answer 3

用VBO解决方案：

#define OFFSET_BUFFER(bytes) ((GLfloat *)NULL + bytes)

float angle = 0.0f;

float vertices[72] =
{
    -1.0f, -1.0f, 1.0f,//VO - 0
    1.0f, -1.0f, 1.0f,//V1 - 1
    -1.0f, 1.0f, 1.0f,//V2 - 2
    1.0f, 1.0f, 1.0f,//V3 - 3

    -1.0f, -1.0f, -1.0f,//V4 - 4
    1.0f, -1.0f, -1.0f,//V5 - 5
    -1.0f, 1.0f, -1.0f,//V6 - 6
    1.0f, 1.0f, -1.0f,//V7 - 7

    -1.0f, 1.0f, 1.0f,//V2 - 8
    1.0f, 1.0f, 1.0f,//V3 - 9
    -1.0f, 1.0f, -1.0f,//V6 - 10
    1.0f, 1.0f, -1.0f,//V7 - 11

    -1.0f, -1.0f, 1.0f,//VO - 12
    1.0f, -1.0f, 1.0f,//V1 - 13
    -1.0f, -1.0f, -1.0f,//V4 - 14
    1.0f, -1.0f, -1.0f,//V5 - 15

    -1.0f, -1.0f, 1.0f,//VO - 16
    -1.0f, 1.0f, 1.0f,//V2 - 17
    -1.0f, -1.0f, -1.0f,//V4 - 18
    -1.0f, 1.0f, -1.0f,//V6 - 19

    1.0f, -1.0f, 1.0f,//V1 - 20
    1.0f, 1.0f, 1.0f,//V3 - 21
    1.0f, -1.0f, -1.0f,//V5 - 22
    1.0f, 1.0f, -1.0f,//V7 - 23
}; 

GLubyte indices[36] =
{
    0,1,2, 1,3,2,
    6,7,5, 6,5,4,
    8,9,10, 9,10,11,
    12,13,14, 13,14,15,
    17,16,18, 17,18,19,
    20,21,22, 21,22,23
}; 

float textures[48] =
{
    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3

    0.0f, 1.0f,//0
    1.0f, 1.0f,//1
    0.0f, 0.0f,//2
    1.0f, 0.0f,//3
}; 

int main(int argc, char *argv[])
{
    SDL_Init(SDL_INIT_VIDEO);
    SDL_WM_SetCaption("Texture Mapping",NULL);
    SDL_SetVideoMode(500, 500, 32, SDL_OPENGL);

    bool continuer = true;
    SDL_Event event;
    GLuint texCube;
    GLuint VBO[3];

    glClearDepth(1.0f);
    glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
    glEnable(GL_DEPTH_TEST);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(70.0f, (float)500.0f / (float)500.0f, 1.0f, 3000.0f);
    glewInit();

    texCube = loadTexture("caisse.jpg");

    glGenBuffers(2, VBO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, VBO[1]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    glBindBuffer(GL_ARRAY_BUFFER, VBO[2]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(textures), textures, GL_STATIC_DRAW);


    glEnable(GL_TEXTURE_2D);

    while (continuer)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        SDL_WaitEvent(&event);
        switch(event.type)
        {
            case SDL_QUIT:
                continuer = false;
        }

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        gluLookAt(0.0f, 0.0f, 3.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

        //Draw Cube ---------------------------------------

        glPushMatrix();
        glRotatef(angle, 1.0f, 1.0f, 0.0f);

        glBindTexture(GL_TEXTURE_2D, texCube);

        glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
        glVertexPointer(3, GL_FLOAT, 0, OFFSET_BUFFER(0));
        glBindBuffer(GL_ARRAY_BUFFER, VBO[2]);
        glTexCoordPointer(2, GL_FLOAT, 0, OFFSET_BUFFER(0));

        glEnableClientState(GL_VERTEX_ARRAY);
        glEnableClientState(GL_TEXTURE_COORD_ARRAY);

        glDrawElements(GL_TRIANGLES, 48, GL_UNSIGNED_BYTE, OFFSET_BUFFER(0));

        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);

        //-------------------------------------------------

        angle += 1.0f;

        glPopMatrix();

        glFlush();
        SDL_GL_SwapBuffers();
    }

    glDisable(GL_TEXTURE_2D);
    SDL_Quit();

    return 0;
}

Answer 4

如果你真的想保存几个字节，你仍然可以分解几个顶点（16个顶点而不是24个顶点）。您可以考虑没有两个相对面的立方体，并分别添加这两个面。以下是IQM模型：

# Inter-Quake Export 

mesh "Cube" 

material "cube.tga" 

vp 1 1 -1 
vn 1 1 -1 
vt 0 0 

vp 1 -1 -1 
vn 1 -1 -1 
vt 0 1 

vp -1 -1 -1 
vn -1 -1 -1 
vt 1 1 

vp -1 1 -1 
vn -1 1 -1 
vt 1 0 

vp 1 1 1 
vn 1 1 1 
vt 1 0 

vp -1 1 1 
vn -1 1 1 
vt 0 0 

vp -1 -1 1 
vn -1 -1 1 
vt 0 1 

vp 1 -1 1 
vn 1 -1 1 
vt 1 1 

vp 1 1 -1 
vn 1 1 -1 
vt 0 0 

vp -1 1 -1 
vn -1 1 -1 
vt 1 0 

vp -1 1 1 
vn -1 1 1 
vt 1 1 

vp 1 1 1 
vn 1 1 1 
vt 0 1 

vp 1 1 -1 
vn 1 1 -1 
vt 0 0 

vp -1 1 -1 
vn -1 1 -1 
vt 1 0 

vp -1 1 1 
vn -1 1 1 
vt 1 1 

vp 1 1 1 
vn 1 1 1 
vt 0 1 

fm 0 1 2 
fm 0 2 3 
fm 0 4 7 
fm 0 7 1 
fm 4 6 7 
fm 4 5 6 
fm 5 2 6 
fm 5 3 2 
fm 8 9 10 
fm 8 10 11 
fm 12 15 14 
fm 12 14 13