java - 纹理坐标不起作用？

Question

说真的，我对这段代码很生气，因为它不起作用:

switch(particle) {
case 0:
    glBegin(GL_TRIANGLE_STRIP);         // STONE
        glNormal3f(0.0f, 0.0f, 1.0f);
        glTexCoord2d(1, 1); glVertex3f(x+size, y+size, 0.0f); // Top Right
        glTexCoord2d(0.5, 1); glVertex3f(x-size, y+size, 0.0f); // Top Left
        glTexCoord2d(1, 0.5); glVertex3f(x+size, y-size, 0.0f); // Bottom Right
        glTexCoord2d(0.5, 0.5); glVertex3f(x-size, y-size, 0.0f); // Bottom Left
    glEnd();
    break;
case 1:
    glBegin(GL_TRIANGLE_STRIP);         // EARTH
        glNormal3f(0.0f, 0.0f, 1.0f);
        glTexCoord2d(0.5, 0.5); glVertex3f(x+size, y+size, 0.0f); // Top Right
        glTexCoord2d(0, 0.5); glVertex3f(x-size, y+size, 0.0f); // Top Left
        glTexCoord2d(0.5, 0); glVertex3f(x+size, y-size, 0.0f); // Bottom Right
        glTexCoord2d(0, 0); glVertex3f(x-size, y-size, 0.0f); // Bottom Left
    glEnd();
    break;
}

情况 0 工作正常，但情况 1 没有，我不知道为什么...... 这是图像(32x32，带有两个 16x16 子纹理):

Answer 1

假设案例 0 显然工作正常，案例 1 的纹理坐标是错误的。它们应该是:

glBegin(GL_TRIANGLE_STRIP);         // EARTH
    glNormal3f(0.0f, 0.0f, 1.0f);
    glTexCoord2d(0.5, 1.0); glVertex3f(x+size, y+size, 0.0f); // Top Right
    glTexCoord2d(0, 1.0); glVertex3f(x-size, y+size, 0.0f); // Top Left
    glTexCoord2d(0.5, 0.5); glVertex3f(x+size, y-size, 0.0f); // Bottom Right
    glTexCoord2d(0, 0.5); glVertex3f(x-size, y-size, 0.0f); // Bottom Left
glEnd();