Question

实际上我是Arduino Neopixel粉丝并试图运行球形POV。对于运行POV，每个图像应该转换为每次旋转中使用的行数，我认为转换计划器POV一定不能这么难以进行java基本处理而像素化成行但我现在不知道如何映射球形图像然后转换为图像线我非常感谢任何评论

Answer 1

Processing编辑器附带了一些示例，其中一个示例将纹理图像映射到球体。它通过将球体分成三角形，然后使用texture()和vertex()函数绘制纹理球体来实现此目的。

您可以转到File > Examples > Topics > Textures > TextureSphere来处理编辑器中的代码，但这里是代码：

/**
 * Texture Sphere 
 * by Gillian Ramsay
 * 
 * Rewritten by Gillian Ramsay to better display the poles.
 * Previous version by Mike 'Flux' Chang (and cleaned up by Aaron Koblin). 
 * Original based on code by Toxi.
 * 
 * A 3D textured sphere with simple rotation control.
 */

int ptsW, ptsH;

PImage img;

int numPointsW;
int numPointsH_2pi; 
int numPointsH;

float[] coorX;
float[] coorY;
float[] coorZ;
float[] multXZ;

void setup() {
  size(640, 360, P3D);
  background(0);
  noStroke();
  img=loadImage("world32k.jpg");
  ptsW=30;
  ptsH=30;
  // Parameters below are the number of vertices around the width and height
  initializeSphere(ptsW, ptsH);
}

// Use arrow keys to change detail settings
void keyPressed() {
  if (keyCode == ENTER) saveFrame();
  if (keyCode == UP) ptsH++;
  if (keyCode == DOWN) ptsH--;
  if (keyCode == LEFT) ptsW--;
  if (keyCode == RIGHT) ptsW++;
  if (ptsW == 0) ptsW = 1;
  if (ptsH == 0) ptsH = 2;
  // Parameters below are the number of vertices around the width and height
  initializeSphere(ptsW, ptsH);
}

void draw() {
  background(0);
  camera(width/2+map(mouseX, 0, width, -2*width, 2*width), 
         height/2+map(mouseY, 0, height, -height, height),
         height/2/tan(PI*30.0 / 180.0), 
         width, height/2.0, 0, 
         0, 1, 0);

  pushMatrix();
  translate(width/2, height/2, 0);  
  textureSphere(200, 200, 200, img);
  popMatrix();
}

void initializeSphere(int numPtsW, int numPtsH_2pi) {

  // The number of points around the width and height
  numPointsW=numPtsW+1;
  numPointsH_2pi=numPtsH_2pi;  // How many actual pts around the sphere (not just from top to bottom)
  numPointsH=ceil((float)numPointsH_2pi/2)+1;  // How many pts from top to bottom (abs(....) b/c of the possibility of an odd numPointsH_2pi)

  coorX=new float[numPointsW];   // All the x-coor in a horizontal circle radius 1
  coorY=new float[numPointsH];   // All the y-coor in a vertical circle radius 1
  coorZ=new float[numPointsW];   // All the z-coor in a horizontal circle radius 1
  multXZ=new float[numPointsH];  // The radius of each horizontal circle (that you will multiply with coorX and coorZ)

  for (int i=0; i<numPointsW ;i++) {  // For all the points around the width
    float thetaW=i*2*PI/(numPointsW-1);
    coorX[i]=sin(thetaW);
    coorZ[i]=cos(thetaW);
  }

  for (int i=0; i<numPointsH; i++) {  // For all points from top to bottom
    if (int(numPointsH_2pi/2) != (float)numPointsH_2pi/2 && i==numPointsH-1) {  // If the numPointsH_2pi is odd and it is at the last pt
      float thetaH=(i-1)*2*PI/(numPointsH_2pi);
      coorY[i]=cos(PI+thetaH); 
      multXZ[i]=0;
    } 
    else {
      //The numPointsH_2pi and 2 below allows there to be a flat bottom if the numPointsH is odd
      float thetaH=i*2*PI/(numPointsH_2pi);

      //PI+ below makes the top always the point instead of the bottom.
      coorY[i]=cos(PI+thetaH); 
      multXZ[i]=sin(thetaH);
    }
  }
}

void textureSphere(float rx, float ry, float rz, PImage t) { 
  // These are so we can map certain parts of the image on to the shape 
  float changeU=t.width/(float)(numPointsW-1); 
  float changeV=t.height/(float)(numPointsH-1); 
  float u=0;  // Width variable for the texture
  float v=0;  // Height variable for the texture

  beginShape(TRIANGLE_STRIP);
  texture(t);
  for (int i=0; i<(numPointsH-1); i++) {  // For all the rings but top and bottom
    // Goes into the array here instead of loop to save time
    float coory=coorY[i];
    float cooryPlus=coorY[i+1];

    float multxz=multXZ[i];
    float multxzPlus=multXZ[i+1];

    for (int j=0; j<numPointsW; j++) { // For all the pts in the ring
      normal(-coorX[j]*multxz, -coory, -coorZ[j]*multxz);
      vertex(coorX[j]*multxz*rx, coory*ry, coorZ[j]*multxz*rz, u, v);
      normal(-coorX[j]*multxzPlus, -cooryPlus, -coorZ[j]*multxzPlus);
      vertex(coorX[j]*multxzPlus*rx, cooryPlus*ry, coorZ[j]*multxzPlus*rz, u, v+changeV);
      u+=changeU;
    }
    v+=changeV;
    u=0;
  }
  endShape();
}

textured sphere

希望这是一个良好的开端，但更普遍的是：Stack Overflow并非真正针对一般＆＃34;我如何做到这一点＆＃34;输入问题。它更专为特定的设计＆＃34;我尝试了X，预期为Y，但却得到了Z而不是＃34;输入问题。你可以发布你尝试过的任何东西吗？您的Minimal, Complete, and Verifiable example在哪里？

如果你不知道如何开始，那么从小处开始：你能得到一个映射到矩形的图像吗？从那里开始工作，如果你遇到困难就发布。祝你好运。

使用处理进行3D图像映射

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