传统的OpenGL纹理立方体

Posted 2021-03-30

我试图在传统的OpenGL中纹理一个长方体。无论我首先渲染的长方体的哪一侧，这一侧都没有正确纹理，因为所有其他边都正确纹理。我先尝试渲染立方体的不同侧面。

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();
}

答案

你正在倒退，在glVertex()之前打电话给glTexCoord()。

glVertex：

glVertex命令在glBegin / glEnd对中用于指定点，线和多边形顶点。当调用glVertex时，当前颜色，法线，纹理坐标和雾坐标与顶点相关联。

所以，通过glTexCoord()和朋友设置你所有的顶点状态，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()将使用最后设置的任何随机纹理坐标。