java如何将纹理环绕球体？

Question

我用drawSphere方法创建了一个类来替换DrawSolidSphere。请参阅下面的代码

但我想知道，我如何在不使用瓷砖的情况下将纹理包裹起来？例如，如果我想在它上面画一张嘴、一只眼睛和一个鼻子，那么我希望它只有一张嘴、两只眼睛和一个鼻子，而不是在整个球体上画100个平铺

我正在使用Jogl和一些库

class Shape {

    public void drawSphere(double radius, int slices, int stacks) {
        gl.glEnable(GL_TEXTURE_2D);
        head.bind(gl); //This method is a shorthand equivalent of gl.glBindTexture(texture.getTarget(), texture.getTextureObject());
        gl.glBegin(GL_QUADS);
        double stack = (2*PI)/stacks;
        double slice = (2*PI)/slices;
        for (double theta = 0; theta < 2 * PI; theta += stack) {
            for (double phi = 0; phi < 2 * PI; phi += slice) {
                Vector p1 = getPoints(phi, theta, radius);
                Vector p2 = getPoints(phi + slice, theta, radius);
                Vector p3 = getPoints(phi + slice, theta + stack, radius);
                Vector p4 = getPoints(phi, theta + stack, radius);
                gl.glTexCoord2d(0, 0);
                gl.glVertex3d(p1.x(), p1.y(), p1.z());
                gl.glTexCoord2d(1, 0);
                gl.glVertex3d(p2.x(), p2.y(), p2.z());
                gl.glTexCoord2d(1, 1);
                gl.glVertex3d(p3.x(), p3.y(), p3.z());
                gl.glTexCoord2d(0, 1);
                gl.glVertex3d(p4.x(), p4.y(), p4.z());
            }
        }
        gl.glEnd();
        gl.glDisable(GL_TEXTURE_2D);
    }

    Vector getPoints(double phi, double theta, double radius) {
        double x = radius * cos(theta) * sin(phi);
        double y = radius * sin(theta) * sin(phi);
        double z = radius * cos(phi);
        return new Vector(x, y, z);
    }
}

Answer 1

你可以直接把纬度和经度映射到纹理坐标上

for (double theta = 0; theta < 2 * PI; theta += stack) {
    for (double phi = 0; phi < 2 * PI; phi += slice) {

只需将theta和phi缩放到0和1之间

double s0 = theta / (2 * PI);
double s1 = (theta + stack) / (2 * PI);
double t0 = phi / (2 * PI);
double t1 = (phi + slice) / (2 * PI);

在texCoord（）调用中使用s0、s1、t0、t1代替0和1