May 18 2007 | 11:33 pm
Too much coffee is making me crazy, or.. well, maybe its not the coffee. ITS MY BRAIIIINNNNNNNNNnnnnn.
I am attempting a Polar to Cartesian transform shader while fighting off my brains attempts to kill me.
My thought is that I should be able to run cartopol shader and then a poltocar and get basically my same output minus weird edge pixels that the math messes up.
However, I get nothing of the sort. I am obviously missing something. Ive looked at Wesleys poltocar code in the kaleidoscope shader mentioned here (second result in google for polar to cartesian glsl btw ;):
" // polar to cartesian conversion vec2 no = vec2(-cos(foldtheta)*radius, -sin(foldtheta)*radius); no = no+0.5*sizea; "
from: https://cycling74.com/forums/index.php? t=msg&goto=61224&rid=0&S=a3d1f2ed3cea8b2a7123521617329dc9
The following is my fragment program in GLSL.
What am I doing wrong? -----------
// define our rectangular texture samplers uniform sampler2DRect tex0;
// define our varying texture coordinates varying vec2 texcoord0; varying vec2 texdim0;
void main (void) { const float pi=3.1415926;
vec2 point = texcoord0/texdim0; //normalize coordinates
vec2 normCoord = vec2(2.0) * (point - vec2(0.5)); // center point in texture
float r = length(normCoord); // find hypot - seems nicer than other method. float phi = atan(normCoord.y, normCoord.x)+pi;
vec2 frompol = vec2(r* cos(phi), r* sin(phi)); // this should be correct, yet I get an incorrect output ?
vec2 outputCoord = (frompol/vec2(2.0) + vec2(0.5)) * texdim0; // unnormalize and remap to reg rect tex coords
gl_FragColor = texture2DRect(tex0, outputCoord);
}
v a d e //