c++ - 旧版 OpenGL 纹理立方体

Question

我正在尝试在遗留 OpenGL 中为长方体制作纹理。无论我先渲染长方体的哪一侧，这一侧的纹理都不正确，而所有其他侧的纹理都正确。我尝试先渲染立方体的不同面。

这是绘制立方体的代码，包括它的纹理坐标:

void Objects::cuboidTextured(float width, float height, float depth, float xpos, float ypos, float zpos, float r, float g, float b){
    glMatrixMode(GL_MODELVIEW);

    glPushMatrix();
    glTranslatef(xpos, ypos, zpos);

    glColor3f(r, g, b);

    glBegin(GL_QUADS);
    glVertex3f(  width, -height, depth );
    glTexCoord2f(1,0);
    glVertex3f(  width,  height, depth );
    glTexCoord2f(1,1);
    glVertex3f( -width,  height, depth );
    glTexCoord2f(0,1);
    glVertex3f( -width, -height, depth );
    glTexCoord2f(0,0);
    glEnd();

    glBegin(GL_QUADS);
    glVertex3f( width, -height, -depth );
    glTexCoord2f(1,0);
    glVertex3f( width,  height, -depth );
    glTexCoord2f(1,1);
    glVertex3f( width,  height,  depth );
    glTexCoord2f(0,1);
    glVertex3f( width, -height,  depth );
    glTexCoord2f(0,0);
    glEnd();

    glBegin(GL_QUADS);
    glVertex3f( -width, -height, depth );
    glTexCoord2f(1,0);
    glVertex3f( -width,  height, depth );
    glTexCoord2f(1,1);
    glVertex3f( -width,  height, -depth );
    glTexCoord2f(0,1);
    glVertex3f( -width, -height, -depth );
    glTexCoord2f(0,0);
    glEnd();

    glBegin(GL_QUADS);
    glVertex3f(  width,  height,  depth );
    glTexCoord2f(1,0);
    glVertex3f(  width,  height, -depth );
    glTexCoord2f(1,1);
    glVertex3f( -width,  height, -depth );
    glTexCoord2f(0,1);
    glVertex3f( -width,  height,  depth );
    glTexCoord2f(0,0);
    glEnd();

    glBegin(GL_QUADS);
    glVertex3f(  width, -height, -depth );
    glTexCoord2f(0,1);
    glVertex3f(  width, -height,  depth );
    glTexCoord2f(0,0);
    glVertex3f( -width, -height,  depth );
    glTexCoord2f(1,1);
    glVertex3f( -width, -height, -depth );
    glTexCoord2f(1,0);
    glEnd();

    glBegin(GL_QUADS);
    glVertex3f( -width, -height, -depth);       
    glTexCoord2f(1,0);
    glVertex3f( -width,  height, -depth);      
    glTexCoord2f(1,1);
    glVertex3f(  width,  height, -depth);      
    glTexCoord2f(0,1);
    glVertex3f(  width, -height, -depth); 
    glTexCoord2f(0,0);
    glEnd();

    glPopMatrix();
}

Answer 1

你在倒着做，在 glTexCoord() 之前调用 glVertex()。

glVertex :

glVertex commands are used within glBegin/glEnd pairs to specify point, line, and polygon vertices. The current color, normal, texture coordinates, and fog coordinate are associated with the vertex when glVertex is called.

因此，通过 glTexCoord() 和 friend 设置所有顶点状态，然后调用 glVertex():

glBegin(GL_QUADS);
glTexCoord2f(1,0);
glVertex3f( width, -height, -depth );
glTexCoord2f(1,1);
glVertex3f( width,  height, -depth );
glTexCoord2f(0,1);
glVertex3f( width,  height,  depth );
glTexCoord2f(0,0);
glVertex3f( width, -height,  depth );
glEnd();

否则 glVertex() 将使用上次设置的任何随机纹理坐标。