通過角度和距離得到x和y的陰影位置php

Question

我對圖像有一個水印，我想用php創建它的陰影GD.how我可以計算距離，陰影有多遠以及在什麼位置位置，如果我有隻從水印

for example 
$shadowAngle = 90;// in radian 
$shadowDistance = 100// in % means 100 percent away from watermark 

$watermark_x = 320; //width of watermark 
$watermark_y = 320; //height of watermark 

$watermark_Pointx = 640; // x of watermark on background Image 
$watermark_Pointy = 140; // y of watermark on background Image 

$shadow_Pointx = ? // x of shadow on background Image 
$shadow_Pointy = ? // y of shadow on background Image 

如何可以通過使用$ shadowAngle計算影子的開始點（$ shadow_Pointx，$ shadow_Pointy）和$ shadowdistance

Answer 1

角度和距離這個等式如何：

$shadow_Pointx = $watermark_Pointx + ($shadowDistance/100 * $watermark_x * sin($shadowAngle)) 

$shadow_Pointy = $watermark_Pointy + ($shadowDistance/100 * $watermark_y * cos($shadowAngle)) 

通過假設90度將設置陰影水印的右側，我想結果應該是960140 ..

什麼