04、真正的3D物体

创建日期：2024-06-21
更新日期：2025-01-12
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<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>04_真正的3D物体</title>

    <script type="text/javascript" src="Oak3D_v_0_5.js"></script>
    <script id="shader-fs" type="x-shader/x-fragment">

        precision mediump float;

        varying vec4 vColor;

        void main(void) {
        gl_FragColor = vColor;
        }
    </script>

    <script id="shader-vs" type="x-shader/x-vertex">
        attribute vec3 aVertexPosition;
        attribute vec4 aVertexColor;

        uniform mat4 uMVMatrix;
        uniform mat4 uPMatrix;

        varying vec4 vColor;

        void main(void) {
        gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
        vColor = aVertexColor;
        }
    </script>

    <script type="text/javascript">

        var gl;

        function initGL(canvas) {
            try {
                gl = canvas.getContext("experimental-webgl");
                gl.viewportWidth = canvas.width;
                gl.viewportHeight = canvas.height;
            } catch (e) {
            }
            if (!gl) {
                alert("Could not initialise WebGL, sorry :-(");
            }
        }

        function getShader(gl, id) {
            var shaderScript = document.getElementById(id);
            if (!shaderScript) {
                return null;
            }

            var str = "";
            var k = shaderScript.firstChild;
            while (k) {
                if (k.nodeType == 3) {
                    str += k.textContent;
                }
                k = k.nextSibling;
            }

            var shader;
            if (shaderScript.type == "x-shader/x-fragment") {
                shader = gl.createShader(gl.FRAGMENT_SHADER);
            } else if (shaderScript.type == "x-shader/x-vertex") {
                shader = gl.createShader(gl.VERTEX_SHADER);
            } else {
                return null;
            }

            gl.shaderSource(shader, str);
            gl.compileShader(shader);

            if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
                alert(gl.getShaderInfoLog(shader));
                return null;
            }

            return shader;
        }

        var shaderProgram;

        function initShaders() {
            var fragmentShader = getShader(gl, "shader-fs");
            var vertexShader = getShader(gl, "shader-vs");

            shaderProgram = gl.createProgram();
            gl.attachShader(shaderProgram, vertexShader);
            gl.attachShader(shaderProgram, fragmentShader);
            gl.linkProgram(shaderProgram);

            if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
                alert("Could not initialise shaders");
            }

            gl.useProgram(shaderProgram);

            shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
            gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

            shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
            gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute);

            shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
            shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
        }

        var mvMatrix;
        var mvMatrixStack = [];
        var pMatrix;

        function mvPushMatrix() {
            var copy = new okMat4();
            mvMatrix.clone(copy);
            mvMatrixStack.push(copy);
        }

        function mvPopMatrix() {
            if (mvMatrixStack.length == 0) {
                throw "Invalid popMatrix!";
            }
            mvMatrix = mvMatrixStack.pop();
        }

        function setMatrixUniforms() {
            gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix.toArray());
            gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix.toArray());
        }

        var pyramidVertexPositionBuffer;
        var pyramidVertexColorBuffer;
        var cubeVertexPositionBuffer;
        var cubeVertexColorBuffer;
        var cubeVertexIndexBuffer;

        function initBuffers() {
            pyramidVertexPositionBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexPositionBuffer);
            var vertices = [
                // Front face
                 0.0, 1.0, 0.0,
                -1.0, -1.0, 1.0,
                 1.0, -1.0, 1.0,

                // Right face
                 0.0, 1.0, 0.0,
                 1.0, -1.0, 1.0,
                 1.0, -1.0, -1.0,

                // Back face
                 0.0, 1.0, 0.0,
                 1.0, -1.0, -1.0,
                -1.0, -1.0, -1.0,

                // Left face
                 0.0, 1.0, 0.0,
                -1.0, -1.0, -1.0,
                -1.0, -1.0, 1.0
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
            pyramidVertexPositionBuffer.itemSize = 3;
            pyramidVertexPositionBuffer.numItems = 12;

            pyramidVertexColorBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexColorBuffer);
            var colors = [
                // Front face
                1.0, 0.0, 0.0, 1.0,
                0.0, 1.0, 0.0, 1.0,
                0.0, 0.0, 1.0, 1.0,

                // Right face
                1.0, 0.0, 0.0, 1.0,
                0.0, 0.0, 1.0, 1.0,
                0.0, 1.0, 0.0, 1.0,

                // Back face
                1.0, 0.0, 0.0, 1.0,
                0.0, 1.0, 0.0, 1.0,
                0.0, 0.0, 1.0, 1.0,

                // Left face
                1.0, 0.0, 0.0, 1.0,
                0.0, 0.0, 1.0, 1.0,
                0.0, 1.0, 0.0, 1.0
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
            pyramidVertexColorBuffer.itemSize = 4;
            pyramidVertexColorBuffer.numItems = 12;

            cubeVertexPositionBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
            vertices = [
                // Front face
                -1.0, -1.0, 1.0,
                 1.0, -1.0, 1.0,
                 1.0, 1.0, 1.0,
                -1.0, 1.0, 1.0,

                // Back face
                -1.0, -1.0, -1.0,
                -1.0, 1.0, -1.0,
                 1.0, 1.0, -1.0,
                 1.0, -1.0, -1.0,

                // Top face
                -1.0, 1.0, -1.0,
                -1.0, 1.0, 1.0,
                 1.0, 1.0, 1.0,
                 1.0, 1.0, -1.0,

                // Bottom face
                -1.0, -1.0, -1.0,
                 1.0, -1.0, -1.0,
                 1.0, -1.0, 1.0,
                -1.0, -1.0, 1.0,

                // Right face
                 1.0, -1.0, -1.0,
                 1.0, 1.0, -1.0,
                 1.0, 1.0, 1.0,
                 1.0, -1.0, 1.0,

                // Left face
                -1.0, -1.0, -1.0,
                -1.0, -1.0, 1.0,
                -1.0, 1.0, 1.0,
                -1.0, 1.0, -1.0
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
            cubeVertexPositionBuffer.itemSize = 3;
            cubeVertexPositionBuffer.numItems = 24;

            cubeVertexColorBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexColorBuffer);
            colors = [
                [1.0, 0.0, 0.0, 1.0], // Front face
                [1.0, 1.0, 0.0, 1.0], // Back face
                [0.0, 1.0, 0.0, 1.0], // Top face
                [1.0, 0.5, 0.5, 1.0], // Bottom face
                [1.0, 0.0, 1.0, 1.0], // Right face
                [0.0, 0.0, 1.0, 1.0]  // Left face
            ];
            var unpackedColors = [];
            for (var i in colors) {
                var color = colors[i];
                for (var j = 0; j < 4; j++) {
                    unpackedColors = unpackedColors.concat(color);
                }
            }
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(unpackedColors), gl.STATIC_DRAW);
            cubeVertexColorBuffer.itemSize = 4;
            cubeVertexColorBuffer.numItems = 24;

            cubeVertexIndexBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
            var cubeVertexIndices = [
                0, 1, 2, 0, 2, 3,    // Front face
                4, 5, 6, 4, 6, 7,    // Back face
                8, 9, 10, 8, 10, 11,  // Top face
                12, 13, 14, 12, 14, 15, // Bottom face
                16, 17, 18, 16, 18, 19, // Right face
                20, 21, 22, 20, 22, 23  // Left face
            ];
            gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
            cubeVertexIndexBuffer.itemSize = 1;
            cubeVertexIndexBuffer.numItems = 36;
        }

        var rPyramid = 0;
        var rCube = 0;

        function drawScene() {
            gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
            gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

            pMatrix = okMat4Proj(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);

            mvMatrix = okMat4Trans(-1.5, 0.0, -8.0);

            mvPushMatrix();
            mvMatrix.rotY(OAK.SPACE_LOCAL, rPyramid, true);

            gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexPositionBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, pyramidVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.bindBuffer(gl.ARRAY_BUFFER, pyramidVertexColorBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, pyramidVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);

            setMatrixUniforms();
            gl.drawArrays(gl.TRIANGLES, 0, pyramidVertexPositionBuffer.numItems);

            mvPopMatrix();

            mvMatrix = okMat4Trans(1.5, 0.0, -8.0);

            mvPushMatrix();
            mvMatrix.rot(OAK.SPACE_LOCAL, rCube, 1.0, 1.0, 1.0, true);

            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexColorBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, cubeVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
            setMatrixUniforms();
            gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);

            mvPopMatrix();

        }

        var lastTime = 0;

        function animate() {
            var timeNow = new Date().getTime();
            if (lastTime != 0) {
                var elapsed = timeNow - lastTime;

                rPyramid += (90 * elapsed) / 1000.0;
                rCube -= (75 * elapsed) / 1000.0;
            }
            lastTime = timeNow;
        }

        function tick() {
            okRequestAnimationFrame(tick);
            drawScene();
            animate();
        }

        function webGLStart() {
            var canvas = document.getElementById("lesson04-canvas");
            initGL(canvas);
            initShaders();
            initBuffers();

            gl.clearColor(0.0, 0.0, 0.0, 1.0);
            gl.enable(gl.DEPTH_TEST);

            tick();
        }
    </script>
</head>
<body onload="webGLStart();">
    <canvas id="lesson04-canvas" style="border: none;" width="500" height="500"></canvas>
</body>

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简介

一个来自三线小城市的程序员开发经验总结。

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