javascript - The picture I draw is invisible after I reset the width and height of the canvas -
in js file:
function main_part2() { var canvas = document.getelementbyid("viewport"); var context = canvas.getcontext("2d"); var eye = new vector(0.5, 0.5, -0.5); raycasting(context, eye, part2); } function change_size() { var canvas = document.getelementbyid("viewport"); var width = document.getelementbyid("width").value; var height = document.getelementbyid("height").value; canvas.width = width; canvas.height = height; main_part2(); } in html file:
<body onload="main_part2();"> <canvas id="viewport" width="512" height="512" style="background-color: black"></canvas><br><br> <label for="width">width: </label><input id="width" type="number"><br><br> <label for="height">height: </label><input id="height" type="number"><br><br> <button type="submit" onclick="change_size()">change</button> i try reset width , height of canvas through 2 inputs , draw new picture according new canvas. however, when click button, canvas resized, raycasting function, draw picture, makes no effect. how make work?
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