07、平行光和环境光

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>07_平行光和环境光</title>
    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">

    <script type="text/javascript" src="Oak3D_v_0_5.js"></script>

    <script id="shader-fs" type="x-shader/x-fragment">

        precision mediump float;

        varying vec2 vTextureCoord;
        varying vec3 vLightWeighting;

        uniform sampler2D uSampler;

        void main(void) {
        vec4 textureColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
        gl_FragColor = vec4(textureColor.rgb * vLightWeighting, textureColor.a);
        }
    </script>

    <script id="shader-vs" type="x-shader/x-vertex">
        attribute vec3 aVertexPosition;
        attribute vec3 aVertexNormal;
        attribute vec2 aTextureCoord;

        uniform mat4 uMVMatrix;
        uniform mat4 uPMatrix;
        uniform mat4 uNMatrix;

        uniform vec3 uAmbientColor;

        uniform vec3 uLightingDirection;
        uniform vec3 uDirectionalColor;

        uniform bool uUseLighting;

        varying vec2 vTextureCoord;
        varying vec3 vLightWeighting;

        void main(void) {
        gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
        vTextureCoord = aTextureCoord;

        if (!uUseLighting) {
        vLightWeighting = vec3(1.0, 1.0, 1.0);
        } else {
        vec3 transformedNormal = (uNMatrix * vec4(aVertexNormal, 1.0)).xyz;
        float directionalLightWeighting = max(dot(transformedNormal, uLightingDirection), 0.0);
        vLightWeighting = uAmbientColor + uDirectionalColor * directionalLightWeighting;
        }
        }
    </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.vertexNormalAttribute = gl.getAttribLocation(shaderProgram, "aVertexNormal");
            gl.enableVertexAttribArray(shaderProgram.vertexNormalAttribute);

            shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
            gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);

            shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
            shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
            shaderProgram.nMatrixUniform = gl.getUniformLocation(shaderProgram, "uNMatrix");
            shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
            shaderProgram.useLightingUniform = gl.getUniformLocation(shaderProgram, "uUseLighting");
            shaderProgram.ambientColorUniform = gl.getUniformLocation(shaderProgram, "uAmbientColor");
            shaderProgram.lightingDirectionUniform = gl.getUniformLocation(shaderProgram, "uLightingDirection");
            shaderProgram.directionalColorUniform = gl.getUniformLocation(shaderProgram, "uDirectionalColor");
        }

        function handleLoadedTexture(texture) {
            gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);

            gl.bindTexture(gl.TEXTURE_2D, texture);
            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.image);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
            gl.generateMipmap(gl.TEXTURE_2D);

            gl.bindTexture(gl.TEXTURE_2D, null);
        }

        var crateTexture;

        function initTexture() {
            crateTexture = gl.createTexture();
            crateTexture.image = new Image();
            crateTexture.image.onload = function () {
                handleLoadedTexture(crateTexture)
            }

            crateTexture.image.src = "crate.gif";
        }

        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 normalMatrix = mvMatrix.inverse().transpose();
            gl.uniformMatrix4fv(shaderProgram.nMatrixUniform, false, normalMatrix.toArray());
        }

        var xRot = 0;
        var xSpeed = 3;

        var yRot = 0;
        var ySpeed = -3;

        var z = -5.0;

        var currentlyPressedKeys = {};

        function handleKeyDown(event) {
            currentlyPressedKeys[event.keyCode] = true;
        }

        function handleKeyUp(event) {
            currentlyPressedKeys[event.keyCode] = false;
        }

        function handleKeys() {
            if (currentlyPressedKeys[33]) {
                // Page Up
                z -= 0.05;
            }
            if (currentlyPressedKeys[34]) {
                // Page Down
                z += 0.05;
            }
            if (currentlyPressedKeys[37]) {
                // Left cursor key
                ySpeed -= 1;
            }
            if (currentlyPressedKeys[39]) {
                // Right cursor key
                ySpeed += 1;
            }
            if (currentlyPressedKeys[38]) {
                // Up cursor key
                xSpeed -= 1;
            }
            if (currentlyPressedKeys[40]) {
                // Down cursor key
                xSpeed += 1;
            }
        }

        var cubeVertexPositionBuffer;
        var cubeVertexNormalBuffer;
        var cubeVertexTextureCoordBuffer;
        var cubeVertexIndexBuffer;

        function initBuffers() {
            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;

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

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

                // Top face
                 0.0, 1.0, 0.0,
                 0.0, 1.0, 0.0,
                 0.0, 1.0, 0.0,
                 0.0, 1.0, 0.0,

                // Bottom face
                 0.0, -1.0, 0.0,
                 0.0, -1.0, 0.0,
                 0.0, -1.0, 0.0,
                 0.0, -1.0, 0.0,

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

                // Left face
                -1.0, 0.0, 0.0,
                -1.0, 0.0, 0.0,
                -1.0, 0.0, 0.0,
                -1.0, 0.0, 0.0
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexNormals), gl.STATIC_DRAW);
            cubeVertexNormalBuffer.itemSize = 3;
            cubeVertexNormalBuffer.numItems = 24;

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

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

                // Top face
                0.0, 1.0,
                0.0, 0.0,
                1.0, 0.0,
                1.0, 1.0,

                // Bottom face
                1.0, 1.0,
                0.0, 1.0,
                0.0, 0.0,
                1.0, 0.0,

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

                // Left face
                0.0, 0.0,
                1.0, 0.0,
                1.0, 1.0,
                0.0, 1.0
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
            cubeVertexTextureCoordBuffer.itemSize = 2;
            cubeVertexTextureCoordBuffer.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;
        }

        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(0.0, 0.0, z);

            mvMatrix.rotX(OAK.SPACE_LOCAL, xRot, true);
            mvMatrix.rotY(OAK.SPACE_LOCAL, yRot, true);

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

            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexNormalBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute, cubeVertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
            gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.activeTexture(gl.TEXTURE0);
            gl.bindTexture(gl.TEXTURE_2D, crateTexture);
            gl.uniform1i(shaderProgram.samplerUniform, 0);
            var lighting = document.getElementById("lighting").checked;
            gl.uniform1i(shaderProgram.useLightingUniform, lighting);
            if (lighting) {
                gl.uniform3f(
                    shaderProgram.ambientColorUniform,
                    parseFloat(document.getElementById("ambientR").value),
                    parseFloat(document.getElementById("ambientG").value),
                    parseFloat(document.getElementById("ambientB").value)
                );

                var lightingDirection = new okVec3(
                    parseFloat(document.getElementById("lightDirectionX").value),
                    parseFloat(document.getElementById("lightDirectionY").value),
                    parseFloat(document.getElementById("lightDirectionZ").value)
                );

                var adjustedLD = lightingDirection.normalize(false);
                adjustedLD = okVec3MulVal(adjustedLD, -1.0);
                gl.uniform3fv(shaderProgram.lightingDirectionUniform, adjustedLD.toArray());

                gl.uniform3f(
                    shaderProgram.directionalColorUniform,
                    parseFloat(document.getElementById("directionalR").value),
                    parseFloat(document.getElementById("directionalG").value),
                    parseFloat(document.getElementById("directionalB").value)
                );
            }

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

        var lastTime = 0;

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

                xRot += (xSpeed * elapsed) / 1000.0;
                yRot += (ySpeed * elapsed) / 1000.0;
            }
            lastTime = timeNow;
        }

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

        function webGLStart() {
            var canvas = document.getElementById("lesson07-canvas");
            initGL(canvas);
            initShaders();
            initBuffers();
            initTexture();

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

            document.onkeydown = handleKeyDown;
            document.onkeyup = handleKeyUp;

            tick();
        }
    </script>
</head>

<body onload="webGLStart();">
    <canvas id="lesson07-canvas" style="border: none;" width="500" height="500"></canvas>

    <br />
    <input type="checkbox" id="lighting" checked /> 开启光照<br />
    （使用<code>Page Up</code>和<code>Page Down</code>键来进行缩放）

    <br />
    <h2>平行光：</h2>

    <table style="border: 0; padding: 10px;">
        <tr>
            <td><b>方向：</b>
            <td>X: <input type="text" id="lightDirectionX" value="-0.25" />
            <td>Y: <input type="text" id="lightDirectionY" value="-0.25" />
            <td>Z: <input type="text" id="lightDirectionZ" value="-1.0" />
        </tr>
        <tr>
            <td><b>颜色：</b>
            <td>R: <input type="text" id="directionalR" value="0.8" />
            <td>G: <input type="text" id="directionalG" value="0.8" />
            <td>B: <input type="text" id="directionalB" value="0.8" />
        </tr>
    </table>

    <h2>环境光：</h2>
    <table style="border: 0; padding: 10px;">
        <tr>
            <td><b>颜色：</b>
            <td>R: <input type="text" id="ambientR" value="0.2" />
            <td>G: <input type="text" id="ambientG" value="0.2" />
            <td>B: <input type="text" id="ambientB" value="0.2" />
        </tr>
    </table>
</body>

</html>

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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