我正在尝试使用此代码使用GL_POLYGON
将纹理映射到圆圈:
void drawCircleOutline(Circle c, int textureindex)
{
float angle, radian, x, y; // values needed by drawCircleOutline
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, textureLib[textureindex]);
glBegin(GL_POLYGON);
for (angle=0.0; angle<360.0; angle+=2.0)
{
radian = angle * (pi/180.0f);
x = (float)cos(radian) * c.r + c.pos.x;
y = (float)sin(radian) * c.r + c.pos.y;
glTexCoord2f(x, y);
glVertex2f(x, y);
}
glEnd();
glDisable(GL_TEXTURE_2D);
}
运行时看起来像这样。
应该是这样的:
答案 0 :(得分:8)
尝试:
radian = angle * (pi/180.0f);
xcos = (float)cos(radian);
ysin = (float)sin(radian);
x = xcos * c.r + c.pos.x;
y = ysin * c.r + c.pos.y;
tx = xcos * 0.5 + 0.5;
ty = ysin * 0.5 + 0.5;
glTexCoord2f(tx, ty);
glVertex2f(x, y);