In Photoshop we can do distort option in the image. In iOS that option achieve using the CATransform3D matrix. below is the iOS code I get from online in this question enter link description here.
func rectToQuad(
rect:CGRect,
_ x1a:CGFloat, _ y1a:CGFloat,
_ x2a:CGFloat, _ y2a:CGFloat,
_ x3a:CGFloat, _ y3a:CGFloat,
_ x4a:CGFloat, _ y4a:CGFloat )->(CATransform3D)
{
let X = rect.origin.x;
let Y = rect.origin.y;
let W = rect.size.width;
let H = rect.size.height;
print("X, \(X)!")
print("Y, \(Y)!")
print("W, \(W)!")
print("H, \(H)!")
print("rect tl x, \(x1a), y, \(y1a)")
print("rect tr x, \(x2a), y, \(y2a)")
print("rect bl x, \(x3a), y, \(y3a)")
print("rect br x, \(x4a), y, \(y4a)")
let y21 = y2a - y1a;
let y32 = y3a - y2a;
let y43 = y4a - y3a;
let y14 = y1a - y4a;
let y31 = y3a - y1a;
let y42 = y4a - y2a;
print("y21, \(y21)!")
print("y32, \(y32)!")
print("y43, \(y43)!")
print("y14, \(y14)!")
print("y31, \(y31)!")
print("y42, \(y42)!")
let a = -H*(x2a*x3a*y14 + x2a*x4a*y31 - x1a*x4a*y32 + x1a*x3a*y42);
let b = W*(x2a*x3a*y14 + x3a*x4a*y21 + x1a*x4a*y32 + x1a*x2a*y43);
print("a, \(a)!")
print("b, \(b)!")
let c0 = -H*W*x1a*(x4a*y32 - x3a*y42 + x2a*y43)
let cx = H*X*(x2a*x3a*y14 + x2a*x4a*y31 - x1a*x4a*y32 + x1a*x3a*y42)
let cy = -W*Y*(x2a*x3a*y14 + x3a*x4a*y21 + x1a*x4a*y32 + x1a*x2a*y43)
let c = c0 + cx + cy
print("c, \(c)!")
let d = H*(-x4a*y21*y3a + x2a*y1a*y43 - x1a*y2a*y43 - x3a*y1a*y4a + x3a*y2a*y4a);
let e = W*(x4a*y2a*y31 - x3a*y1a*y42 - x2a*y31*y4a + x1a*y3a*y42);
print("d, \(d)!")
print("e, \(e)!")
let f0 = -W*H*(x4a*y1a*y32 - x3a*y1a*y42 + x2a*y1a*y43)
let fx = H*X*(x4a*y21*y3a - x2a*y1a*y43 - x3a*y21*y4a + x1a*y2a*y43)
let fy = -W*Y*(x4a*y2a*y31 - x3a*y1a*y42 - x2a*y31*y4a + x1a*y3a*y42)
let f = f0 + fx + fy
print("f, \(f)!")
let g = H*(x3a*y21 - x4a*y21 + (-x1a + x2a)*y43);
let h = W*(-x2a*y31 + x4a*y31 + (x1a - x3a)*y42);
print("g, \(g)!")
print("h, \(h)!")
let i0 = H*W*(x3a*y42 - x4a*y32 - x2a*y43)
let ix = H*X*(x4a*y21 - x3a*y21 + x1a*y43 - x2a*y43)
let iy = W*Y*(x2a*y31 - x4a*y31 - x1a*y42 + x3a*y42)
var i = i0 + ix + iy
print("i, \(i)!")
let kEpsilon:CGFloat = 0.0001;
if(fabs(i) < kEpsilon) { i = kEpsilon * (i > 0 ? 1.0 : -1.0); }
return CATransform3D(m11:a/i, m12:d/i, m13:0, m14:g/i,
m21:b/i, m22:e/i, m23:0, m24:h/i,
m31:0, m32:0, m33:1, m34:0,
m41:c/i, m42:f/i, m43:0, m44:1.0)
}
I try to implement that matrix in Android App using NDK and opengles 3.0 c++
void TransformTool::rectToQuad(Rect rect, Point tl,Point tr,Point bl,Point br){
float* worldViewMatrix = dynamic_cast<ImageLayer *>(imageLayer)->getWorldViewMatrix();
long double W = rect.width;
long double H = rect.height;
long double X = 0;
long double Y = 0;
CCELogError("W: %Lf, H: %Lf",W,H);
CCELogError("X: %Lf, Y: %Lf",X,Y);
long double x1a = tl.x;
long double y1a = tl.y;
long double x2a = tr.x;
long double y2a = tr.y;
long double x3a = bl.x;
long double y3a = bl.y;
long double x4a = br.x;
long double y4a = br.y;
long double y21 = y2a - y1a;
long double y32 = y3a - y2a;
long double y43 = y4a - y3a;
long double y14 = y1a - y4a;
long double y31 = y3a - y1a;
long double y42 = y4a - y2a;
CCELogError("y21: %Lf",y21);
CCELogError("y32: %Lf",y32);
CCELogError("y43: %Lf",y43);
CCELogError("y14: %Lf",y14);
CCELogError("y31: %Lf",y31);
CCELogError("y42: %Lf",y42);
long double a = -H*(x2a*x3a*y14 + x2a*x4a*y31 - x1a*x4a*y32 + x1a*x3a*y42);
CCELogError("a: %Lf",a);
long double b = W*(x2a*x3a*y14 + x3a*x4a*y21 + x1a*x4a*y32 + x1a*x2a*y43);
CCELogError("b: %Lf",b);
long double c0 = -H*W*x1a*(x4a*y32 - x3a*y42 + x2a*y43);
long double cx = H*X*(x2a*x3a*y14 + x2a*x4a*y31 - x1a*x4a*y32 + x1a*x3a*y42);
long double cy =-W*Y*(x2a*x3a*y14 + x3a*x4a*y21 + x1a*x4a*y32 + x1a*x2a*y43);
long double c = c0 + cx + cy;
CCELogError("c: %Lf",c);
long double d = H*(-x4a*y21*y3a + x2a*y1a*y43 - x1a*y2a*y43 - x3a*y1a*y4a + x3a*y2a*y4a);
long double e = W*(x4a*y2a*y31 - x3a*y1a*y42 - x2a*y31*y4a + x1a*y3a*y42);
CCELogError("d: %Lf",d);
CCELogError("e: %Lf",e);
long double f0 = -W*H*(x4a*y1a*y32 - x3a*y1a*y42 + x2a*y1a*y43);
long double fx = H*X*(x4a*y21*y3a - x2a*y1a*y43 - x3a*y21*y4a + x1a*y2a*y43);
long double fy = -W*Y*(x4a*y2a*y31 - x3a*y1a*y42 - x2a*y31*y4a + x1a*y3a*y42);
long double f = f0 + fx + fy;
CCELogError("f: %Lf",f);
long double g = H*(x3a*y21 - x4a*y21 + (-x1a + x2a)*y43);
long double h = W*(-x2a*y31 + x4a*y31 + (x1a - x3a)*y42);
CCELogError("g: %Lf",g);
CCELogError("h: %Lf",h);
long double i0 = H*W*(x3a*y42 - x4a*y32 - x2a*y43);
long double ix = H*X*(x4a*y21 - x3a*y21 + x1a*y43 - x2a*y43);
long double iy = W*Y*(x2a*y31 - x4a*y31 - x1a*y42 + x3a*y42);
long double i = i0 + ix + iy;
CCELogError("i: %Lf",i);
long double kEpsilon = 0.0001;
if(abs(i) < kEpsilon){
i = kEpsilon * (i > 0 ? 1.0f : -1.0f);
}
CCELogError("i: %Lf",i);
long double m11 = a/i;
long double m12 = d/i;
long double m13 = 0;
long double m14 = (g/i);
long double m21 = b/i;
long double m22 = e/i;
long double m23 = 0;
long double m24 = (h/i);
long double m31 = 0;
long double m32 = 0;
long double m33 = 1;
long double m34 = 0;
long double m41 = c/i;
long double m42 = f/i;
long double m43 = 0;
long double m44 = 1;
CCELogError("a/i: %Lf",m11);
CCELogError("b/i: %Lf",m21);
CCELogError("c/i: %.15Lf",m41);
CCELogError("d/i: %.15Lf",m12);
CCELogError("e/i: %Lf",m22);
CCELogError("f/i: %.15Lf",m42);
CCELogError("g/i: %Lf",m14);
CCELogError("h/i: %Lf",m24);
Matrix::translate(tempViewMatrix1,
-this->focalPointTranslation[0],
-this->focalPointTranslation[1],
false);
tempViewMatrix1[0] = m11;
tempViewMatrix1[1] = m12;
tempViewMatrix1[2] = m13;
tempViewMatrix1[3] = m14;
tempViewMatrix1[4] = m21;
tempViewMatrix1[5] = m22;
tempViewMatrix1[6] = m23;
tempViewMatrix1[7] = m24;
tempViewMatrix1[8] = m31;
tempViewMatrix1[9] = m32;
tempViewMatrix1[10] = m33;
tempViewMatrix1[11] = m34;
tempViewMatrix1[12] = m41;
tempViewMatrix1[13] = m42;
tempViewMatrix1[14] = m43;
tempViewMatrix1[15] = m44;
Matrix::translate(tempViewMatrix1,
this->focalPointTranslation[0],
this->focalPointTranslation[1],
false);
Matrix::multiply(transformViewMatrix,transformViewMatrix,tempViewMatrix1,false);
}
but this does not give correct transform. I try to use viewmatrix to change the position of the vertex of images.
I need to find a matrix that works distort on images in opengles 3.0.
