headchaser.js

/// <reference path="webgl.d.ts" />

let headchaser = class {
    constructor(gl, pos) {
        this.positionBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, this.positionBuffer);

        this.positions = [
             // Front face
             -0.15, 0.9, 0.0,
              0.15, 0.9, 0.0,
              0.15, 1.2, 0.0,
             -0.15, 1.2, 0.0,
             //Back Face
            -0.15, 1.2, 0.0,
             0.15, 1.2, 0.0,
             0.15, 1.2, -0.2,
            -0.15, 1.2, -0.2,
            // Front face
             -0.15, 0.9, 0.0,
             -0.15, 0.9, -0.2,
             -0.15, 1.2, -0.2,
             -0.15, 1.2, 0.0,
             //Back Face
             0.15, 0.9, 0.0,
             0.15, 0.9, -0.2,
             0.15, 1.2, -0.2,
             0.15, 1.2, 0.0,
        ];

        this.rotation = 0;

        this.pos = pos;

        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(this.positions), gl.STATIC_DRAW);
        
        const textureCoordBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, textureCoordBuffer);

  const textureCoordinates = [
    // Front
    0.0,  0.0,
    1.0,  0.0,
    1.0,  1.0,
    0.0,  1.0,
    // Back
    0.0,  0.0,
    1.0,  0.0,
    1.0,  1.0,
    0.0,  1.0,
    // Front
    0.0,  0.0,
    1.0,  0.0,
    1.0,  1.0,
    0.0,  1.0,
    // Back
    0.0,  0.0,
    1.0,  0.0,
    1.0,  1.0,
    0.0,  1.0,
  ];

  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoordinates),
                gl.STATIC_DRAW);

        // Build the element array buffer; this specifies the indices
        // into the vertex arrays for each face's vertices.

        const indexBuffer = gl.createBuffer();
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);

        // This array defines each face as two triangles, using the
        // indices into the vertex array to specify each triangle's
        // position.

        const indices = [
            0, 1, 2,    0, 2, 3, // front
            4, 5, 6,    4, 6, 7,
            8, 9, 10,   8, 10, 11,
            12, 13, 14,  12, 14, 15,
        ];

        // Now send the element array to GL

        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,
            new Uint16Array(indices), gl.STATIC_DRAW);

        this.buffer = {
            position: this.positionBuffer,
             textureCoord: textureCoordBuffer,
            indices: indexBuffer,
        }

    }

    drawheadchaser(gl, projectionMatrix, programInfo, deltaTime, texture) {
        const modelViewMatrix = mat4.create();
        mat4.translate(
            modelViewMatrix,
            modelViewMatrix,
            this.pos
        );
        
        //this.rotation += Math.PI / (((Math.random()) % 100) + 50);

        mat4.rotate(modelViewMatrix,
            modelViewMatrix,
            this.rotation,
            [1, 1, 1]);

        {
            const numComponents = 3;
            const type = gl.FLOAT;
            const normalize = false;
            const stride = 0;
            const offset = 0;
            gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer.position);
            gl.vertexAttribPointer(
                programInfo.attribLocations.vertexPosition,
                numComponents,
                type,
                normalize,
                stride,
                offset);
            gl.enableVertexAttribArray(
                programInfo.attribLocations.vertexPosition);
        }

        // tell webgl how to pull out the texture coordinates from buffer
		{
		    const num = 2; // every coordinate composed of 2 values
		    const type = gl.FLOAT; // the data in the buffer is 32 bit float
		    const normalize = false; // don't normalize
		    const stride = 0; // how many bytes to get from one set to the next
		    const offset = 0; // how many bytes inside the buffer to start from
		    gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer.textureCoord);
		    gl.vertexAttribPointer(programInfo.attribLocations.textureCoord, num, type, normalize, stride, offset);
		    gl.enableVertexAttribArray(programInfo.attribLocations.textureCoord);
		}

		  // Tell WebGL we want to affect texture unit 0
		  gl.activeTexture(gl.TEXTURE0);
		
		  // Bind the texture to texture unit 0
		  gl.bindTexture(gl.TEXTURE_2D, texture);
		
		  // Tell the shader we bound the texture to texture unit 0
		  gl.uniform1i(programInfo.uniformLocations.uSampler, 0);

        // Tell WebGL which indices to use to index the vertices
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.buffer.indices);

        // Tell WebGL to use our program when drawing

        gl.useProgram(programInfo.program);

        // Set the shader uniforms

        gl.uniformMatrix4fv(
            programInfo.uniformLocations.projectionMatrix,
            false,
            projectionMatrix);
        gl.uniformMatrix4fv(
            programInfo.uniformLocations.modelViewMatrix,
            false,
            modelViewMatrix);

        {
            const vertexCount = 24;
            const type = gl.UNSIGNED_SHORT;
            const offset = 0;
            gl.drawElements(gl.TRIANGLES, vertexCount, type, offset);
        }

    }
};

//
// Initialize a texture and load an image.
// When the image finished loading copy it into the texture.
//
function loadTexture(gl, url) {
  const texture = gl.createTexture();
  gl.bindTexture(gl.TEXTURE_2D, texture);

  // Because images have to be download over the internet
  // they might take a moment until they are ready.
  // Until then put a single pixel in the texture so we can
  // use it immediately. When the image has finished downloading
  // we'll update the texture with the contents of the image.
  const level = 0;
  const internalFormat = gl.RGBA;
  const width = 1;
  const height = 1;
  const border = 0;
  const srcFormat = gl.RGBA;
  const srcType = gl.UNSIGNED_BYTE;
  const pixel = new Uint8Array([0, 0, 255, 255]);  // opaque blue
  gl.texImage2D(gl.TEXTURE_2D, level, internalFormat,
                width, height, border, srcFormat, srcType,
                pixel);

  const image = new Image();
  image.onload = function() {
    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.texImage2D(gl.TEXTURE_2D, level, internalFormat,
                  srcFormat, srcType, image);

    // WebGL1 has different requirements for power of 2 images
    // vs non power of 2 images so check if the image is a
    // power of 2 in both dimensions.
    if (isPowerOf2(image.width) && isPowerOf2(image.height)) {
       // Yes, it's a power of 2. Generate mips.
       gl.generateMipmap(gl.TEXTURE_2D);
    } else {
       // No, it's not a power of 2. Turn off mips and set
       // wrapping to clamp to edge
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    }
  };
  image.src = url;

  return texture;
}

function isPowerOf2(value) {
  return (value & (value - 1)) == 0;
}