4顏色漸變邏輯需要

Question

我需要創建4個顏色漸變邏輯。其中一個帖子給了我計算4種顏色梯度的模式。但是我有差異來實現它。

我能計算出E點的顏色（中間的一個），但我不知道如何開發梯度從中

我的代碼

COLORREF NewColor = RGB(255,0,0); 
COLORREF NewColor2 = RGB(0,255,0); 
COLORREF NewColor3 = RGB(0,0,255); 
COLORREF NewColor4 = RGB(255,255,0); 
red_low = GetRValue(NewColor); 
blue_low = GetBValue(NewColor); 
green_low = GetGValue(NewColor); 
red_high = GetRValue(NewColor2); 
green_high= GetGValue(NewColor2); 
blue_high = GetBValue(NewColor2); 

red_low2 = GetRValue(NewColor3); 
blue_low2 = GetBValue(NewColor3); // divide the difference in colours by the number of steps 
green_low2 = GetGValue(NewColor3); 
red_high2 = GetRValue(NewColor4); 
green_high2 = GetGValue(NewColor4); // divide the difference in colours by the number of steps 
blue_high2 = GetBValue(NewColor4);   
double distance_a = sqrt((double)((0-W)^2+(0-H/2)^2)); 
    double distance_b = sqrt((double)((350-W/2)^2+(0-H/2)^2)); 
    double distance_c = sqrt((double)((350-W/2)^2+(100-H/2)^2)); 
    double distance_d = sqrt((double)((0-W/2)^2+(100-H/2)^2)); 
    double sum_distances = distance_a + distance_b + distance_c + distance_d; 
    double red = (red_low*distance_a + red_high*distance_b + red_low2*distance_c+ red_high2*distance_d)/sum_distances; 
    double green = (green_low*distance_a + green_high*distance_b + green_low2*distance_c+ green_high2*distance_d)/sum_distances; 
    double blue = (blue_low*distance_a + blue_high*distance_b + blue_low2*distance_c+ blue_high2*distance_d)/sum_distances; 
COLORREF Color_E= RGB(red,green,blue);  

安逸幫助如何futher碼是讚賞。

Answer 1

下面是計算給定四個角落顏色時（x，y）顏色的代碼。

#include <vector> 
#include <cassert> 
#include <windows.h> 

using namespace std; 

int interpolate(int a, int b, int c, int d, double t, double s) 
{ 
    return (int)(a*(1-t)*(1-s) + b*t*(1-s) + c*(1-t)*s + d*t*s); 
} 

COLORREF interpolateColors(const vector<COLORREF> &cornercolors, int W, int H, int x, int y) 
{ 
    assert(cornercolors.size() == 4); 
    double t = ((double)x)/W; 
    double s = ((double)y)/H; 
    return RGB(interpolate(GetRValue(cornercolors[0]), GetRValue(cornercolors[1]), GetRValue(cornercolors[2]), GetRValue(cornercolors[3]), t, s), 
       interpolate(GetGValue(cornercolors[0]), GetGValue(cornercolors[1]), GetGValue(cornercolors[2]), GetGValue(cornercolors[3]), t, s), 
       interpolate(GetBValue(cornercolors[0]), GetBValue(cornercolors[1]), GetBValue(cornercolors[2]), GetBValue(cornercolors[3]), t, s)); 
}