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Author Topic: (Solved) Camera2D rotation and skew  (Read 263 times)

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Online claude

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(Solved) Camera2D rotation and skew
« on: August 14, 2019, 11:17:00 PM »
As is known, "hidden treasures" in 2D escape time fractals can be revealed by stretching skewed regions.

I tried implementing this in a frag, but there is a big problem - when the transform is enabled, the mouse interactions don't match up to the image, so sensible navigation is often impossible (the higher the StretchAmount the harder it is, while non-zero RotateAngle adds another smaller layer of confusion).

So, I would need to modify the core FragM Camera2D code. It needs to be automatically enabled for compatible frags with sane defaults (no errors or GUI for frags that don't have those uniforms).

Here's my current Camera2D vertex code:

Code: [Select]

out vec2 coord;
out vec2 viewCoord;

#group Camera

uniform float Zoom; slider[0,1,1e16] NotLockable
uniform float ZoomFactor; slider[-100,0,100]
uniform vec2 pixelSize;

uniform bool EnableTransform; checkbox[true]
uniform float RotateAngle; slider[-360,0,360]
uniform float StretchAngle; slider[-360,0,360]
uniform float StretchAmount; slider[-100,0,100]

void main(void)
  mat2 transform = mat2(1.0, 0.0, 0.0, 1.0);
  if (EnableTransform)
    float b = radians(RotateAngle);
    float bc = cos(b);
    float bs = sin(b);
    float a = radians(StretchAngle);
    float ac = cos(a);
    float as = sin(a);
    float s = sqrt(pow(2.0, StretchAmount));
    mat2 m1 = mat2(ac, as, -as, ac);
    mat2 m2 = mat2(s, 0.0, 0.0, 1.0 / s);
    mat2 m3 = mat2(ac, -as, as, ac);
    mat2 m4 = mat2(bc, bs, -bs, bc);
    transform = m1 * m2 * m3 * m4;
  float ar = float(pixelSize.y / pixelSize.x);
  coord = transform * ((gl_ProjectionMatrix * gl_Vertex).xy * vec2(ar, 1.0)) / (float(Zoom) * pow(2.0, ZoomFactor));
  viewCoord = gl_Vertex.xy;
  gl_Position =  gl_Vertex;

(adding of Center is done in the fragment part).


Linkback: https://fractalforums.org/index.php?topic=3003.0
« Last Edit: August 25, 2019, 04:25:14 PM by claude, Reason: Prefix to solved as pull request is merged »

Online claude

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Re: Camera2D rotation and skew
« Reply #1 on: August 15, 2019, 11:07:11 PM »
I modified the core of FragM's Camera2D to support this and made a pull request.

Attached is an unskewed view from under the bow of a mini-ship in DoubleTest.frag with my modifications to the (Progressive)2D(-4).frag code and core.

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