HTML5 Game - Rotation around the center point

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  3. Canvas
  4. Rotate

Description

Rotation around the center point

Demo

ResultView the demo in separate window 

<!DOCTYPE html>  
<html> 
<head> 
<style> 
#canvas { /*from ww  w .  ja v a2s.  co  m*/
  border:1px solid #03F; 
  background:#CFC; 
} 
</style> 
</head> 
<body> 
<canvas id="canvas" width="640" height="480"></canvas> 
<script> 
  let context = document.getElementById('canvas').getContext('2d'); 
    
      //draw black square 
      context.fillStyle = "black"; 
      context.fillRect(20,20 ,25,25); 

      //now draw a red square 
      context.setTransform(1,0,0,1,0,0); 
      let angleInRadians = 45 * Math.PI / 180; 
      let x = 100; 
      let y = 100; 
      let width = 50; 
      let height = 50; 

      context.translate(x+.5*width, y+.5*height); 
      context.rotate(angleInRadians); 
      context.fillStyle = "red"; 
      context.fillRect(-.5*width,-.5*height , width, height); 


</script> 



</body> 
</html>

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