В этой главе мы рассмотрим пример, показывающий, как рисовать вращающийся трехмерный куб с помощью WebGL.
Пример — нарисуйте вращающийся 3D-куб
Следующая программа показывает, как нарисовать вращающийся 3D-куб —
<!doctype html> <html> <body> <canvas width = "570" height = "570" id = "my_Canvas"></canvas> <script> /*============= Creating a canvas =================*/ var canvas = document.getElementById('my_Canvas'); gl = canvas.getContext('experimental-webgl'); /*============ Defining and storing the geometry =========*/ var vertices = [ -1,-1,-1, 1,-1,-1, 1, 1,-1, -1, 1,-1, -1,-1, 1, 1,-1, 1, 1, 1, 1, -1, 1, 1, -1,-1,-1, -1, 1,-1, -1, 1, 1, -1,-1, 1, 1,-1,-1, 1, 1,-1, 1, 1, 1, 1,-1, 1, -1,-1,-1, -1,-1, 1, 1,-1, 1, 1,-1,-1, -1, 1,-1, -1, 1, 1, 1, 1, 1, 1, 1,-1, ]; var colors = [ 5,3,7, 5,3,7, 5,3,7, 5,3,7, 1,1,3, 1,1,3, 1,1,3, 1,1,3, 0,0,1, 0,0,1, 0,0,1, 0,0,1, 1,0,0, 1,0,0, 1,0,0, 1,0,0, 1,1,0, 1,1,0, 1,1,0, 1,1,0, 0,1,0, 0,1,0, 0,1,0, 0,1,0 ]; var indices = [ 0,1,2, 0,2,3, 4,5,6, 4,6,7, 8,9,10, 8,10,11, 12,13,14, 12,14,15, 16,17,18, 16,18,19, 20,21,22, 20,22,23 ]; // Create and store data into vertex buffer var vertex_buffer = gl.createBuffer (); gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); // Create and store data into color buffer var color_buffer = gl.createBuffer (); gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); // Create and store data into index buffer var index_buffer = gl.createBuffer (); gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer); gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indices), gl.STATIC_DRAW); /*=================== Shaders =========================*/ var vertCode = 'attribute vec3 position;'+ 'uniform mat4 Pmatrix;'+ 'uniform mat4 Vmatrix;'+ 'uniform mat4 Mmatrix;'+ 'attribute vec3 color;'+//the color of the point 'varying vec3 vColor;'+ 'void main(void) { '+//pre-built function 'gl_Position = Pmatrix*Vmatrix*Mmatrix*vec4(position, 1.);'+ 'vColor = color;'+ '}'; var fragCode = 'precision mediump float;'+ 'varying vec3 vColor;'+ 'void main(void) {'+ 'gl_FragColor = vec4(vColor, 1.);'+ '}'; var vertShader = gl.createShader(gl.VERTEX_SHADER); gl.shaderSource(vertShader, vertCode); gl.compileShader(vertShader); var fragShader = gl.createShader(gl.FRAGMENT_SHADER); gl.shaderSource(fragShader, fragCode); gl.compileShader(fragShader); var shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertShader); gl.attachShader(shaderProgram, fragShader); gl.linkProgram(shaderProgram); /* ====== Associating attributes to vertex shader =====*/ var Pmatrix = gl.getUniformLocation(shaderProgram, "Pmatrix"); var Vmatrix = gl.getUniformLocation(shaderProgram, "Vmatrix"); var Mmatrix = gl.getUniformLocation(shaderProgram, "Mmatrix"); gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); var position = gl.getAttribLocation(shaderProgram, "position"); gl.vertexAttribPointer(position, 3, gl.FLOAT, false,0,0) ; // Position gl.enableVertexAttribArray(position); gl.bindBuffer(gl.ARRAY_BUFFER, color_buffer); var color = gl.getAttribLocation(shaderProgram, "color"); gl.vertexAttribPointer(color, 3, gl.FLOAT, false,0,0) ; // Color gl.enableVertexAttribArray(color); gl.useProgram(shaderProgram); /*==================== MATRIX =====================*/ function get_projection(angle, a, zMin, zMax) { var ang = Math.tan((angle*.5)*Math.PI/180);//angle*.5 return [ 0.5/ang, 0 , 0, 0, 0, 0.5*a/ang, 0, 0, 0, 0, -(zMax+zMin)/(zMax-zMin), -1, 0, 0, (-2*zMax*zMin)/(zMax-zMin), 0 ]; } var proj_matrix = get_projection(40, canvas.width/canvas.height, 1, 100); var mov_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]; var view_matrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]; // translating z view_matrix[14] = view_matrix[14]-6;//zoom /*==================== Rotation ====================*/ function rotateZ(m, angle) { var c = Math.cos(angle); var s = Math.sin(angle); var mv0 = m[0], mv4 = m[4], mv8 = m[8]; m[0] = c*m[0]-s*m[1]; m[4] = c*m[4]-s*m[5]; m[8] = c*m[8]-s*m[9]; m[1]=c*m[1]+s*mv0; m[5]=c*m[5]+s*mv4; m[9]=c*m[9]+s*mv8; } function rotateX(m, angle) { var c = Math.cos(angle); var s = Math.sin(angle); var mv1 = m[1], mv5 = m[5], mv9 = m[9]; m[1] = m[1]*c-m[2]*s; m[5] = m[5]*c-m[6]*s; m[9] = m[9]*c-m[10]*s; m[2] = m[2]*c+mv1*s; m[6] = m[6]*c+mv5*s; m[10] = m[10]*c+mv9*s; } function rotateY(m, angle) { var c = Math.cos(angle); var s = Math.sin(angle); var mv0 = m[0], mv4 = m[4], mv8 = m[8]; m[0] = c*m[0]+s*m[2]; m[4] = c*m[4]+s*m[6]; m[8] = c*m[8]+s*m[10]; m[2] = c*m[2]-s*mv0; m[6] = c*m[6]-s*mv4; m[10] = c*m[10]-s*mv8; } /*================= Drawing ===========================*/ var time_old = 0; var animate = function(time) { var dt = time-time_old; rotateZ(mov_matrix, dt*0.005);//time rotateY(mov_matrix, dt*0.002); rotateX(mov_matrix, dt*0.003); time_old = time; gl.enable(gl.DEPTH_TEST); gl.depthFunc(gl.LEQUAL); gl.clearColor(0.5, 0.5, 0.5, 0.9); gl.clearDepth(1.0); gl.viewport(0.0, 0.0, canvas.width, canvas.height); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); gl.uniformMatrix4fv(Pmatrix, false, proj_matrix); gl.uniformMatrix4fv(Vmatrix, false, view_matrix); gl.uniformMatrix4fv(Mmatrix, false, mov_matrix); gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, index_buffer); gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0); window.requestAnimationFrame(animate); } animate(0); </script> </body> </html>
Если вы запустите этот пример, он выдаст следующий вывод: