c++ - 梯度生成产生奇怪的伪像

Question

当我使用以下代码生成渐变时，它会在图像中心附近产生类似渐变的奇怪裂缝。

生成代码:

void getRgb(GLfloat* pixels1,GLubyte* out)//convert fractional values into color
{
  for (int i = 0;i < 90*90;i++)
  {
    out[(i*3)+0] = pixels1[i]*255;
    out[(i*3)+1] = pixels1[i]*255;
    out[(i*3)+2] = pixels1[i]*255;
  }
}

//gradient generation
multiplier = new GLfloat[90*90];// calc multiplier map

for(int i = 0;i < 90;i++)//2d to 1d
{
  for (int j = 0;j < 90;j++)
  multiplier[i*90 + j] = cos((j)*(3.14/180));
}



SDL_Surface * image = SDL_CreateRGBSurface(SDL_SWSURFACE, 89, 89, 24, 0x000000FF, 0x0000FF00, 0x00FF0000, 0);
GLubyte* save = new GLubyte[90*90*3];
getRgb(multiplier,save);
image->pixels = save;


std::string path = "map.bmp";
SDL_SaveBMP(image, path.c_str());
delete save;
image->pixels = NULL;
SDL_FreeSurface(image);

结果artifact .

Answer 1

那是因为您从余弦中得到了负值。这些不能很好地处理无符号整数像素值，它应该在 [0, 255] 范围内。