平铺渲染glFrustum剪裁平面计算

Question

我试图让平铺的渲染器工作（想法是通过将其分解成块并单独渲染来渲染一个大视锥体。）

我有一些代码可以将带有视角的标准透视投影转换为左，右，上和下剪裁平面，然后可以将其传递到glFrustum。

我被迫坚决打破了这一点。

Answer 1

经过几次失误后，我制作了以下内容：

//"int  rect[4]" is the pixel rectangle of the original view
//"int rect2[4]" is the pixel subrectangle within rect corresponding to the new view
//"left", "right", "bottom", and "top" are the left, right, bottom, and top clipping
//    planes of the old view, respectively.

float diff_x = right -   left;
float diff_y =   top - bottom;

result_left   = (float)(rect2[0]         ) / (float)(rect[2]) * diff_x  +    left;
result_right  = (float)(rect2[0]+rect2[2]) / (float)(rect[2]) * diff_x  +    left;
result_bottom = (float)(rect2[1]         ) / (float)(rect[3]) * diff_y  +  bottom;
result_top    = (float)(rect2[1]+rect2[3]) / (float)(rect[3]) * diff_y  +  bottom;