add a simple editor

glsl/raymarching.js

    console.error(e);
  }
  
  function clearError() {
    errorEl.textContent = "";
  }
  
  function compileShader(gl, type, shaderSrc) {
    var shader = gl.createShader(type);
    gl.shaderSource(shader, shaderSrc);
  transition: right 0.1s;
  right: 0;
}
#editor {
  position: absolute;
  top: 0;
  left: 0;
  border: none;
  background-color: rgba(255, 255, 255, 0.5);
  min-width: 72ex;
  height: 100vh;
}
  `
  document.head.appendChild(styleEl);
  
  addSliders(sidebarEl, sliders);
  
  tt.render();
  
  var editor = {};
  editor.el = document.createElement("textarea");
  editor.el.id = "editor";
  editor.el.value = fragmentShaderSrc;
  document.body.appendChild(editor.el);
  
  editor.el.onkeydown = function(ev) {
    try {
      if (ev.ctrlKey && ev.keyCode == 13) {
        tt = TwoTriangles(canvas, editor.el.value);
        sidebarEl.innerHTML = "";
        sliders = findSliders(fragmentShaderSrc);
        initSliders(tt.gl, tt.program, sliders, function(ev) {
          requestAnimationFrame(tt.render);
        });
        addSliders(sidebarEl, sliders);
        tt.render();
        clearError();
      }
    } catch (e) {
      displayError(e);
    }
  }
} catch (e) {
  displayError(e);
}