I made a Noise class using the Perlin Noise from Unity like this:
public static float[,] GetNoise(Vector2Int initialOffset, float scale, float persistance, float lacunarity, int octaves)
{
float[,] noiseMap = new float[Chunk.width, Chunk.height];
float maxHeight = 0;
float minHeight = 0;
for (int y = 0; y < Chunk.height; y++)
{
for (int x = 0; x < Chunk.width; x++)
{
float amplitude = 1;
float frequency = 1;
float noiseHeight = 0;
for (int oc = 0; oc < octaves; oc++)
{
float coordX = (x + initialOffset.x) / scale * frequency;
float coordY = (y + initialOffset.y) / scale * frequency;
float perlin = Mathf.PerlinNoise(coordX, coordY) * 2 - 1;
noiseHeight += perlin * amplitude;
amplitude *= persistance;
frequency *= lacunarity;
}
if (noiseHeight < minHeight)
{
minHeight = noiseHeight;
}
if (noiseHeight > maxHeight)
{
maxHeight = noiseHeight;
}
noiseMap[x, y] = noiseHeight;
}
}
for (int y = 0; y < Chunk.height; y++)
{
for (int x = 0; x < Chunk.width; x++)
{
noiseMap[x, y] = Mathf.InverseLerp(minHeight, maxHeight, noiseMap[x, y]);
}
}
return noiseMap;
}
However this code is giving me repeating patterns like this:
What am I doing wrong? Or there is no way to get rid of the patterns?
I got it working, not very well, but working. The way I did was I generate the height map for every tile in the chunk, then I did some random placing of tiles, while having in account the height map. Something like this:
if (heightMap[x, y] < 0.3 && Random.value < 0.5)
// Add tile
This way I got this result:
EDIT:
Doing some more research about Perlin Noise I found out that it just doesn't like negative coords for some reason, so I did this way, hope this helps someone!
so .. fixed the negative coords like this:
//account for negatives (ex. -1 % 256 = -1, needs to loop around to 255)
if (noiseOffset.x < 0)
noiseOffset = new Vector2(noiseOffset.x + noiseRange.x, noiseOffset.y);
if (noiseOffset.y < 0)
noiseOffset = new Vector2(noiseOffset.x, noiseOffset.y + noiseRange.y);
I'm trying to implement a median filter in RenderScript. But the work of the code is not stable. Reading elements not from the current line rsGetElementAt_uchar4 (inputAlloc, x , y + a ) causes errors. What is the problem ? Is there an example of such a filter using RenderScript?
#pragma version(1)
#pragma rs java_package_name(a.myapplication)
#pragma rs_fp_relaxed
rs_allocation inputAlloc;
int bWidht, bHeight;
static uchar4 arrpix[9];
static uchar4 buff;
uchar4 __attribute__((kernel)) median(uchar4 in, uint32_t x, uint32_t y)
{
uchar4 arrpix[9];
uchar4 buff;
if((x<bWidht) && (y<bHeight)){
arrpix[0] = rsGetElementAt_uchar4(inputAlloc, x -1 , y - 1);
arrpix[1] = rsGetElementAt_uchar4(inputAlloc, x , y - 1);
arrpix[2] = rsGetElementAt_uchar4(inputAlloc, x +1 , y - 1);
arrpix[3] = rsGetElementAt_uchar4(inputAlloc, x -1 , y );
arrpix[4] = in;
arrpix[5] = rsGetElementAt_uchar4(inputAlloc, x +1 , y );
arrpix[6] = rsGetElementAt_uchar4(inputAlloc, x -1 , y + 1);
arrpix[7] = rsGetElementAt_uchar4(inputAlloc, x , y + 1);
arrpix[8] = rsGetElementAt_uchar4(inputAlloc, x +1 , y + 1);
for(int i=0; i<4; i++)
for(int i=0; i<=8; i++){
if(arrpix[i].r>arrpix[i+1].r){
buff.r = arrpix[i].r; arrpix[i].r = arrpix[i+1].r;
arrpix[i+1].r = buff.r;}
if(arrpix[i].g>arrpix[i+1].g){
buff.g = arrpix[i].g; arrpix[i].g = arrpix[i+1].g;
arrpix[i+1].g = buff.g;}
if(arrpix[i].b>arrpix[i+1].b){
buff.b = arrpix[i].b; arrpix[i].b = arrpix[i+1].b;
arrpix[i+1].b = buff.b;}
}
}
return arrpix[4];
}
You need to check x>0 and y>0 because 0-1 =-1
Bottom loops don't look completely correct either. Can you fix the spacing and did you mean to use i in both loops?
I'm currently trying to create 3D simplex noise implementation in CG shader for unity. I decided to use this implementation that is originally written in C++ and port it to CG, since they are simmilar.
I've decided to provide permutation and gradient vector as textures, so they can be easily used in code. Everything works fine, except the places that are at the edges of each simplex. This leads to inacceptable visual artifacts that I'd like to fix.
Notice the dotted lines on the texture. I thought it might be a problem with rounding/flooring but I can't figure out which operation causes this. I've tried to play around with the floorings, but nothing helps.
Here is my shader code:
Shader "Custom/PerlinNoise" {
Properties {
_Permutation ("RandomVector (RGB)", 2D) = "white" { }
_Gradient3 ("GradientVector (RGB)", 2D) = "white" { }
}
SubShader {
Pass {
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#include "UnityCG.cginc"
uniform sampler2D _Permutation;
uniform sampler2D _Gradient3;
//Get the i-th int3 gradient. x,y,z in range [-1, 1]
int3 grad3(int i)
{
float2 pos;
pos.x = i / 16.0;
pos.y = 0;
fixed3 tx = tex2D(_Gradient3, pos);
tx = tx * 2.0 - 1;
return tx;
}
//Get the i-th permutation. Result in range [0-255]
int p(int i)
{
float2 pos;
pos.x = i / 256.0;
pos.y = 0.5;
return tex2D(_Permutation, pos).r * 256;
}
float dt(const int3 g, float x, float y, float z)
{
return g.x*x + g.y*y + g.z*z;
}
int fastfloor(const float x)
{
return x > 0 ? (int) x : (int) x - 1;
}
//Almost a copy-paste from the original C++ code
float simplex(const float x, const float y, const float z)
{
float n0, n1, n2, n3; // Noise contributions from the four corners
// Skew the input space to determine which simplex cell we're in
float F3 = 1.0/3.0;
float s = (x+y+z)*F3; // Very nice and simple skew factor for 3D
int i = fastfloor(x+s);
int j = fastfloor(y+s);
int k = fastfloor(z+s);
float G3 = 1.0/6.0; // Very nice and simple unskew factor, too
float t = (i+j+k)*G3;
float X0 = i-t; // Unskew the cell origin back to (x,y,z) space
float Y0 = j-t;
float Z0 = k-t;
float x0 = x-X0; // The x,y,z distances from the cell origin
float y0 = y-Y0;
float z0 = z-Z0;
// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
// Determine which simplex we are in.
int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
if(x0>=y0) {
if(y0>=z0) { i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; } // X Y Z order
else if(x0>=z0) { i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; } // X Z Y order
else { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; } // Z X Y order
}
else { // x0<y0
if(y0<z0) { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; } // Z Y X order
else if(x0<z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; } // Y Z X order
else { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; } // Y X Z order
}
// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
// c = 1/6.
float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
float y1 = y0 - j1 + G3;
float z1 = z0 - k1 + G3;
float x2 = x0 - i2 + 2.0*G3; // Offsets for third corner in (x,y,z) coords
float y2 = y0 - j2 + 2.0*G3;
float z2 = z0 - k2 + 2.0*G3;
float x3 = x0 - 1.0 + 3.0*G3; // Offsets for last corner in (x,y,z) coords
float y3 = y0 - 1.0 + 3.0*G3;
float z3 = z0 - 1.0 + 3.0*G3;
// Work out the hashed gradient indices of the four simplex corners
int ii = i & 255;
int jj = j & 255;
int kk = k & 255;
int gi0 = p(ii+p(jj+p(kk))) % 12;
int gi1 = p(ii+i1+p(jj+j1+p(kk+k1))) % 12;
int gi2 = p(ii+i2+p(jj+j2+p(kk+k2))) % 12;
int gi3 = p(ii+1+p(jj+1+p(kk+1))) % 12;
// Calculate the contribution from the four corners
float t0 = 0.6 - x0*x0 - y0*y0 - z0*z0;
if(t0<0) n0 = 0.0;
else {
t0 *= t0;
n0 = t0 * t0 * dt(grad3(gi0), x0, y0, z0);
}
float t1 = 0.6 - x1*x1 - y1*y1 - z1*z1;
if(t1<0) n1 = 0.0;
else {
t1 *= t1;
n1 = t1 * t1 * dt(grad3(gi1), x1, y1, z1);
}
float t2 = 0.6 - x2*x2 - y2*y2 - z2*z2;
if(t2<0) n2 = 0.0;
else {
t2 *= t2;
n2 = t2 * t2 * dt(grad3(gi2), x2, y2, z2);
}
float t3 = 0.6 - x3*x3 - y3*y3 - z3*z3;
if(t3<0) n3 = 0.0;
else {
t3 *= t3;
n3 = t3 * t3 * dt(grad3(gi3), x3, y3, z3);
}
// Add contributions from each corner to get the final noise value.
// The result is scaled to stay just inside [0,1)
return 16.0*(n0 + n1 + n2 + n3) + 0.5;
}
float4 frag(v2f_img i) : SV_Target
{
float v = simplex(i.uv.x * 4, i.uv.y * 4, _Time);
return fixed4(v, v, v, 1.0);
}
ENDCG
}
}
}
And here are the images that immitate constant data in shader:
Gradinets
Permutation
Remember to assign them to appropiate properties in shader.
I need to rotate an image by very small angle, like 1-5 degrees. Does OpenCV provide simple way of doing that? From reading docs i can assume that getAffineTransform() should be involved, but there is no direct example of doing something like:
IplImage *rotateImage( IplImage *source, double angle);
If you use OpenCV > 2.0 it is as easy as
using namespace cv;
Mat rotateImage(const Mat& source, double angle)
{
Point2f src_center(source.cols/2.0F, source.rows/2.0F);
Mat rot_mat = getRotationMatrix2D(src_center, angle, 1.0);
Mat dst;
warpAffine(source, dst, rot_mat, source.size());
return dst;
}
Note: angle is in degrees, not radians.
See the C++ interface documentation for more details and adapt as you need:
getRotationMatrix
warpAffine
Edit: To down voter: Please comment the reason for down voting a tried and tested code?
#include "cv.h"
#include "highgui.h"
#include "math.h"
int main( int argc, char** argv )
{
IplImage* src = cvLoadImage("lena.jpg", 1);
IplImage* dst = cvCloneImage( src );
int delta = 1;
int angle = 0;
int opt = 1; // 1： rotate & zoom
// 0: rotate only
double factor;
cvNamedWindow("src", 1);
cvShowImage("src", src);
for(;;)
{
float m[6];
CvMat M = cvMat(2, 3, CV_32F, m);
int w = src->width;
int h = src->height;
if(opt)
factor = (cos(angle*CV_PI/180.) + 1.05) * 2;
else
factor = 1;
m[0] = (float)(factor*cos(-angle*2*CV_PI/180.));
m[1] = (float)(factor*sin(-angle*2*CV_PI/180.));
m[3] = -m[1];
m[4] = m[0];
m[2] = w*0.5f;
m[5] = h*0.5f;
cvGetQuadrangleSubPix( src, dst, &M);
cvNamedWindow("dst", 1);
cvShowImage("dst", dst);
if( cvWaitKey(1) == 27 )
break;
angle =(int)(angle + delta) % 360;
}
return 0;
}
UPDATE: See the following code for rotation using warpaffine
https://code.google.com/p/opencvjp-sample/source/browse/trunk/cpp/affine2_cpp.cpp?r=48
#include <cv.h>
#include <highgui.h>
using namespace cv;
int
main(int argc, char **argv)
{
// (1)load a specified file as a 3-channel color image,
// set its ROI, and allocate a destination image
const string imagename = argc > 1 ? argv[1] : "../image/building.png";
Mat src_img = imread(imagename);
if(!src_img.data)
return -1;
Mat dst_img = src_img.clone();
// (2)set ROI
Rect roi_rect(cvRound(src_img.cols*0.25), cvRound(src_img.rows*0.25), cvRound(src_img.cols*0.5), cvRound(src_img.rows*0.5));
Mat src_roi(src_img, roi_rect);
Mat dst_roi(dst_img, roi_rect);
// (2)With specified three parameters (angle, rotation center, scale)
// calculate an affine transformation matrix by cv2DRotationMatrix
double angle = -45.0, scale = 1.0;
Point2d center(src_roi.cols*0.5, src_roi.rows*0.5);
const Mat affine_matrix = getRotationMatrix2D( center, angle, scale );
// (3)rotate the image by warpAffine taking the affine matrix
warpAffine(src_roi, dst_roi, affine_matrix, dst_roi.size(), INTER_LINEAR, BORDER_CONSTANT, Scalar::all(255));
// (4)show source and destination images with a rectangle indicating ROI
rectangle(src_img, roi_rect.tl(), roi_rect.br(), Scalar(255,0,255), 2);
namedWindow("src", CV_WINDOW_AUTOSIZE);
namedWindow("dst", CV_WINDOW_AUTOSIZE);
imshow("src", src_img);
imshow("dst", dst_img);
waitKey(0);
return 0;
}
Check my answer to a similar problem:
Rotating an image in C/C++
Essentially, use cvWarpAffine - I've described how to get the 2x3 transformation matrix from the angle in my previous answer.
Updating full answer for OpenCV 2.4 and up
// ROTATE p by R
/**
* Rotate p according to rotation matrix (from getRotationMatrix2D()) R
* #param R Rotation matrix from getRotationMatrix2D()
* #param p Point2f to rotate
* #return Returns rotated coordinates in a Point2f
*/
Point2f rotPoint(const Mat &R, const Point2f &p)
{
Point2f rp;
rp.x = (float)(R.at<double>(0,0)*p.x + R.at<double>(0,1)*p.y + R.at<double>(0,2));
rp.y = (float)(R.at<double>(1,0)*p.x + R.at<double>(1,1)*p.y + R.at<double>(1,2));
return rp;
}
//COMPUTE THE SIZE NEEDED TO LOSSLESSLY STORE A ROTATED IMAGE
/**
* Return the size needed to contain bounding box bb when rotated by R
* #param R Rotation matrix from getRotationMatrix2D()
* #param bb bounding box rectangle to be rotated by R
* #return Size of image(width,height) that will compleley contain bb when rotated by R
*/
Size rotatedImageBB(const Mat &R, const Rect &bb)
{
//Rotate the rectangle coordinates
vector<Point2f> rp;
rp.push_back(rotPoint(R,Point2f(bb.x,bb.y)));
rp.push_back(rotPoint(R,Point2f(bb.x + bb.width,bb.y)));
rp.push_back(rotPoint(R,Point2f(bb.x + bb.width,bb.y+bb.height)));
rp.push_back(rotPoint(R,Point2f(bb.x,bb.y+bb.height)));
//Find float bounding box r
float x = rp[0].x;
float y = rp[0].y;
float left = x, right = x, up = y, down = y;
for(int i = 1; i<4; ++i)
{
x = rp[i].x;
y = rp[i].y;
if(left > x) left = x;
if(right < x) right = x;
if(up > y) up = y;
if(down < y) down = y;
}
int w = (int)(right - left + 0.5);
int h = (int)(down - up + 0.5);
return Size(w,h);
}
/**
* Rotate region "fromroi" in image "fromI" a total of "angle" degrees and put it in "toI" if toI exists.
* If toI doesn't exist, create it such that it will hold the entire rotated region. Return toI, rotated imge
* This will put the rotated fromroi piece of fromI into the toI image
*
* #param fromI Input image to be rotated
* #param toI Output image if provided, (else if &toI = 0, it will create a Mat fill it with the rotated image roi, and return it).
* #param fromroi roi region in fromI to be rotated.
* #param angle Angle in degrees to rotate
* #return Rotated image (you can ignore if you passed in toI
*/
Mat rotateImage(const Mat &fromI, Mat *toI, const Rect &fromroi, double angle)
{
//CHECK STUFF
// you should protect against bad parameters here ... omitted ...
//MAKE OR GET THE "toI" MATRIX
Point2f cx((float)fromroi.x + (float)fromroi.width/2.0,fromroi.y +
(float)fromroi.height/2.0);
Mat R = getRotationMatrix2D(cx,angle,1);
Mat rotI;
if(toI)
rotI = *toI;
else
{
Size rs = rotatedImageBB(R, fromroi);
rotI.create(rs,fromI.type());
}
//ADJUST FOR SHIFTS
double wdiff = (double)((cx.x - rotI.cols/2.0));
double hdiff = (double)((cx.y - rotI.rows/2.0));
R.at<double>(0,2) -= wdiff; //Adjust the rotation point to the middle of the dst image
R.at<double>(1,2) -= hdiff;
//ROTATE
warpAffine(fromI, rotI, R, rotI.size(), INTER_CUBIC, BORDER_CONSTANT, Scalar::all(0));
//& OUT
return(rotI);
}
IplImage* rotate(double angle, float centreX, float centreY, IplImage* src, bool crop)
{
int w=src->width;
int h=src->height;
CvPoint2D32f centre;
centre.x = centreX;
centre.y = centreY;
CvMat* warp_mat = cvCreateMat(2, 3, CV_32FC1);
cv2DRotationMatrix(centre, angle, 1.0, warp_mat);
double m11= cvmGet(warp_mat,0,0);
double m12= cvmGet(warp_mat,0,1);
double m13= cvmGet(warp_mat,0,2);
double m21= cvmGet(warp_mat,1,0);
double m22= cvmGet(warp_mat,1,1);
double m23= cvmGet(warp_mat,1,2);
double m31= 0;
double m32= 0;
double m33= 1;
double x=0;
double y=0;
double u0= (m11*x + m12*y + m13)/(m31*x + m32*y + m33);
double v0= (m21*x + m22*y + m23)/(m31*x + m32*y + m33);
x=w;
y=0;
double u1= (m11*x + m12*y + m13)/(m31*x + m32*y + m33);
double v1= (m21*x + m22*y + m23)/(m31*x + m32*y + m33);
x=0;
y=h;
double u2= (m11*x + m12*y + m13)/(m31*x + m32*y + m33);
double v2= (m21*x + m22*y + m23)/(m31*x + m32*y + m33);
x=w;
y=h;
double u3= (m11*x + m12*y + m13)/(m31*x + m32*y + m33);
double v3= (m21*x + m22*y + m23)/(m31*x + m32*y + m33);
int left= MAX(MAX(u0,u2),0);
int right= MIN(MIN(u1,u3),w);
int top= MAX(MAX(v0,v1),0);
int bottom= MIN(MIN(v2,v3),h);
ASSERT(left<right&&top<bottom); // throw message?
if (left<right&&top<bottom)
{
IplImage* dst= cvCreateImage( cvGetSize(src), IPL_DEPTH_8U, src->nChannels);
cvWarpAffine(src, dst, warp_mat/*, CV_INTER_LINEAR + CV_WARP_FILL_OUTLIERS, cvScalarAll(0)*/);
if (crop) // crop and resize to initial size
{
IplImage* dst_crop= cvCreateImage(cvSize(right-left, bottom-top), IPL_DEPTH_8U, src->nChannels);
cvSetImageROI(dst,cvRect(left,top,right-left,bottom-top));
cvCopy(dst,dst_crop);
cvReleaseImage(&dst);
cvReleaseMat(&warp_mat);
//ver1
//return dst_crop;
// ver2 resize
IplImage* out= cvCreateImage(cvSize(w, h), IPL_DEPTH_8U, src->nChannels);
cvResize(dst_crop,out);
cvReleaseImage(&dst_crop);
return out;
}
else
{
/*cvLine( dst, cvPoint(left,top),cvPoint(left, bottom), cvScalar(0, 0, 255, 0) ,1,CV_AA);
cvLine( dst, cvPoint(right,top),cvPoint(right, bottom), cvScalar(0, 0, 255, 0) ,1,CV_AA);
cvLine( dst, cvPoint(left,top),cvPoint(right, top), cvScalar(0, 0, 255, 0) ,1,CV_AA);
cvLine( dst, cvPoint(left,bottom),cvPoint(right, bottom), cvScalar(0, 0, 255, 0) ,1,CV_AA);*/
cvReleaseMat(&warp_mat);
return dst;
}
}
else
{
return NULL; //assert?
}
}