Question

我遇到了正确的球体映射问题。我使用世界地图来显示出错的地方。北美从上到下出现在前面，而南美则在另一边颠倒，亚洲等大陆甚至都不在地图上。

Screenshot http://i.troll.ws/3aedbe4b.png

以下代码是sphere-object

class Shape {

    public void drawSphere(double radius, int slices, int stacks) {
        gl.glEnable(GL_TEXTURE_2D);
        head.bind(gl); //Method that binds the world-map (for testing) texture.
        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);
                double s0 = theta / (2 * PI);
                double s1 = (theta + stack) / (2 * PI);
                double t0 = phi / (2 * PI);
                double t1 = (phi + slice) / (2 * PI);

                vectorToNormal(norm(p1));
                gl.glTexCoord2d(s0, t0);
                vectorToVertex(p1);

                vectorToNormal(norm(p2));
                gl.glTexCoord2d(s0, t1);
                vectorToVertex(p2);

                vectorToNormal(norm(p3));
                gl.glTexCoord2d(s1, t1 );
                vectorToVertex(p3);

                vectorToNormal(norm(p4));
                gl.glTexCoord2d(s1, t0);
                vectorToVertex(p4);
            }
        }
        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);
    }

我该如何解决？我试过交换一些坐标和其他东西，但这让我更加困惑。

此外，当我将纹理绑定到它时，似乎有一些文物。这可以解决吗？

Answer 1

你的循环都是从0到2 * PI。其中一个应该只是半圈。你把球体翻了一倍，导致了狡猾的地图和奇怪的人工制品。

Answer 2

感谢JasonD，这解决了它。

for (double theta = 0; theta < 2 * PI; theta += stack) {
    for (double phi = 0; phi < 1 * 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);
        double s0 = theta / (2 * PI);
        double s1 = (theta + stack) / (2 * PI);
        double t0 = phi / (1 * PI);
        double t1 = (phi + slice) / (1 * PI);

在球体上映射纹理的正确方法是什么？

2 个答案: