reorganised file structure

www/js/draw-scene.js

@@ -0,0 +1,51 @@
+function drawScene(gl, programInfo, buffers, time) {
+  gl.clearColor(0.0, 0.0, 0.0, 1.0); // Clear to black, fully opaque
+  gl.clearDepth(1.0);                // Clear everything
+  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
+
+  // NOTE: this is how width/height is taken
+  // const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
+  
+  // Tell WebGL how to pull out the positions from the position
+  // buffer into the vertexPosition attribute.
+  setPositionAttribute(gl, buffers, programInfo);
+
+  gl.useProgram(programInfo.program);
+
+  /* --- Set Uniform Variables --- */
+  // Time since page loaded in seconds
+  gl.uniform1f(
+    programInfo.uniformLocations.time,
+    time,
+  );  
+
+  {
+    const offset = 0;
+    const vertexCount = 4;
+    gl.drawArrays(gl.TRIANGLE_STRIP, offset, vertexCount);
+  }
+}
+
+// Tell WebGL how to pull out the positions from the position
+// buffer into the vertexPosition attribute.
+function setPositionAttribute(gl, buffers, programInfo) {
+  const numComponents = 2; // pull out 2 values per iteration
+  const type = gl.FLOAT; // the data in the buffer is 32bit floats
+  const normalize = false; // don't normalize
+  const stride = 0; // how many bytes to get from one set of values to the next
+  // 0 = use type and numComponents above
+  const offset = 0; // how many bytes inside the buffer to start from
+  gl.bindBuffer(gl.ARRAY_BUFFER, buffers.position);
+  gl.vertexAttribPointer(
+    programInfo.attribLocations.vertexPosition,
+    numComponents,
+    type,
+    normalize,
+    stride,
+    offset,
+  );
+  gl.enableVertexAttribArray(programInfo.attribLocations.vertexPosition);
+}
+
+export { drawScene };
+