c++ - 生成径向梯度的算法

Question

我这里有这个算法:

pc = # the point you are coloring now
p0 = # start point
p1 = # end point
v = p1 - p0
d = Length(v)
v = Normalize(v) # or Scale(v, 1/d)

v0 = pc - p0

t = Dot(v0, v)
t = Clamp(t/d, 0, 1)

color = (start_color * t) + (end_color * (1 - t))

生成点对点线性渐变。对我来说效果很好。我想知道是否有类似的算法来生成径向渐变。类似地，我的意思是解决点 P 处的颜色而不是解决特定颜色处的 P(其中 P 是您正在绘制的坐标)。

谢谢

Answer 1

//loop through vector
//x and y px position
int x = i%w;
int y = i/w;
float d = distance(center,int2(x,y));
//if within the grad circle
if(d < radius)
{
  //somehow set v[i] alpha to this:
  float a = d/r;
}