向香草wegl中的变换立方体添加定向光

Question

如何向webGL中的变换立方体添加方向灯。

我知道它需要法线，并且已经将它们添加到了代码段中（我已将其注释掉了）

还需要在顶点着色器中进行一些数学运算。不幸的是，当我取消注释时，此代码不起作用。

attribute vec4 coords;
  uniform mat4 transformMatrix;
  attribute vec3 normal;
  attribute vec4 colors;
  uniform vec3 lightColor;
  uniform vec3 lightDirection;
  varying vec4 varyingColors;
  uniform mat4 perspectiveMatrix;
  void main(void) {
    vec3 norm = normalize(normal);
    vec3 ld = normalize(lightDirection);
    float dotProduct = max(dot(norm, ld), 0.0);
    vec3 vertexColor = lightColor * colors * dotProduct;
    varyingColors = vec4(vertexColor, 1);
    gl_Position = perspectiveMatrix * transformMatrix  * coords;
  }

var gl,
    shaderProgram,
    vertices,
    matrix = mat4.create(),
    vertexCount,
    indexCount,
    q = quat.create(),
    translate =[-3, 0, -10],
    scale = [1,1,1],
    pivot = [0,0,0];
    
    translate2 = [0, 0, -8],
    scale2 = [3,3,3],
    pivot2 = [1,1,1]


initGL();
createShaders();
createVertices();
createIndices();
draw();

function initGL() {
  var canvas = document.getElementById("canvas");
  gl = canvas.getContext("webgl");
  gl.enable(gl.DEPTH_TEST);
  gl.viewport(0, 0, canvas.width, canvas.height);
  gl.clearColor(1, 1, 1, 1);
}

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

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

function createVertices() {
  vertices = [
    -1, -1, -1,     1, 0, 0, 1,     // 0
     1, -1, -1,     1, 1, 0, 1,     // 1
    -1,  1, -1,     0, 1, 1, 1,     // 2
     1,  1, -1,     0, 0, 1, 1,     // 3
    -1,  1,  1,     1, 0.5, 0, 1,   // 4
     1,  1,  1,     0.5, 1, 1, 1,   // 5
    -1, -1,  1,     1, 0, 0.5, 1,   // 6
     1, -1,  1,     0.5, 0, 1, 1,   // 7
  ];

  vertexCount = vertices.length / 7;

  var buffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);

  var coords = gl.getAttribLocation(shaderProgram, "coords");
  gl.vertexAttribPointer(coords, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 7, 0);
  gl.enableVertexAttribArray(coords); 


/**
var normals = [
    0, 0, 1,   0, 0, 1,    0, 0, 1,   0, 0, 1,
    0, 1, 0,   0, 1, 0,    0, 1, 0,   0, 1, 0,
    0, 0, -1,  0, 0, -1,   0, 0, -1,  0, 0, -1,
    0, -1, 0,  0, -1, 0,   0, -1, 0,  0, -1, 0,
    -1, 0, 0,  -1, 0, 0,   -1, 0, 0,  -1, 0, 0,
    1, 0, 0,   1, 0, 0,    1, 0, 0,   1, 0, 0
  ];
  
  var normalBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(normals), gl.STATIC_DRAW);
  
  var normalLocation = gl.getAttribLocation(shaderProgram, "normal");
  gl.vertexAttribPointer(normalLocation, 3, gl.FLOAT, false, 0, 0);
  gl.enableVertexAttribArray(normalLocation);  
  gl.bindBuffer(gl.ARRAY_BUFFER, null);
  
  var lightColor = gl.getUniformLocation(shaderProgram, "lightColor");
  gl.uniform3f(lightColor, 1, 1, 1);
  
  var lightDirection = gl.getUniformLocation(shaderProgram, "lightDirection");
  gl.uniform3f(lightDirection, 0.5, 1, 0);
 */


  var colorsLocation = gl.getAttribLocation(shaderProgram, "colors");
  gl.vertexAttribPointer(colorsLocation, 4, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 7, Float32Array.BYTES_PER_ELEMENT * 3);

  gl.enableVertexAttribArray(colorsLocation);
  gl.bindBuffer(gl.ARRAY_BUFFER, null);

  

  var perspectiveMatrix = mat4.create();
  mat4.perspective(perspectiveMatrix, 1, canvas.width / canvas.height, 0.1, 11);
  var perspectiveLoc = gl.getUniformLocation(shaderProgram, "perspectiveMatrix");
  gl.uniformMatrix4fv(perspectiveLoc, false, perspectiveMatrix);

}

function createIndices() {
  var indices = [
    0, 1, 2,   1, 2, 3,
    2, 3, 4,   3, 4, 5,
    4, 5, 6,   5, 6, 7,
    6, 7, 0,   7, 0, 1,
    0, 2, 6,   2, 6, 4,
    1, 3, 7,   3, 7, 5
  ];
  indexCount = indices.length;

  var indexBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
  gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint8Array(indices), gl.STATIC_DRAW);


}

function draw(timeMs) {
  requestAnimationFrame(draw);

  let interval = timeMs / 3000
  let t = interval - Math.floor(interval); 

  let trans_t = vec3.lerp([], translate, translate2, t);
  let scale_t = vec3.lerp([], scale, scale2, t);
  let pivot_t = vec3.lerp([], pivot, pivot2, t);

  mat4.fromRotationTranslationScaleOrigin(matrix, q, trans_t, scale_t, pivot_t);

  var transformMatrix = gl.getUniformLocation(shaderProgram, "transformMatrix");
  gl.uniformMatrix4fv(transformMatrix, false, matrix);
  gl.clear(gl.COLOR_BUFFER_BIT);
  gl.drawElements(gl.TRIANGLES, indexCount, gl.UNSIGNED_BYTE, 0);
}


  /*
   * https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Adding_2D_content_to_a_WebGL_context
   */
  function getShader(gl, id) {
    var shaderScript, theSource, currentChild, shader;

    shaderScript = document.getElementById(id);

    if (!shaderScript) {
      return null;
    }

    theSource = "";
    currentChild = shaderScript.firstChild;

    while (currentChild) {
      if (currentChild.nodeType == currentChild.TEXT_NODE) {
        theSource += currentChild.textContent;
      }

      currentChild = currentChild.nextSibling;
    }
    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 {
      // Unknown shader type
      return null;
    }
    gl.shaderSource(shader, theSource);

// Compile the shader program
    gl.compileShader(shader);

// See if it compiled successfully
    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
      alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(shader));
      return null;
    }

    return shader;
  }

<script id="shader-vs" type="x-shader/x-vertex">
attribute vec4 coords;
attribute float pointSize;
uniform mat4 transformMatrix;
attribute vec4 colors;
varying vec4 varyingColors;
uniform mat4 perspectiveMatrix;
void main(void) {
  gl_Position = perspectiveMatrix * transformMatrix  * coords;
  gl_PointSize = pointSize;
  varyingColors = colors;
}
</script>

<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
uniform vec4 color;
varying vec4 varyingColors;
void main(void) {
  gl_FragColor = varyingColors;
}
</script>

<canvas id="canvas" width="600" height="600"></canvas>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/gl-matrix/2.3.2/gl-matrix-min.js"></script>

Answer 1

着色器代码中存在问题：

vec3 vertexColor = lightColor * colors * dotProduct;

color的类型为vec4，但是vertexColor的类型为vec3，因此必须为：

vec3 vertexColor = lightColor * colors.rgb * dotProduct;

您不能将vec4类型的变量分配给vec3类型的变量。

---

调用gl.vertexAttribPointer时，必须先绑定适当的顶点缓冲区。在指定colorsLocation属性的点上，绑定了normals的缓冲区，而不是绑定了顶点和颜色（vertices）的缓冲区。

---

顶点坐标及其属性是元组。如果顶点坐标使用了两次（或在三个侧面中使用了3次），并且每次与一个不同的法向矢量相关联，则必须“复制”坐标。每个顶点坐标都与1个法向矢量完全相关。
参见Rendering meshes with multiple indices。

想象一个3维顶点坐标和一个3维法向矢量为1，但是6维属性。

创建线性化的属性数组：

vertices = [
  [-1, -1, -1,     1, 0, 0, 1],     // 0
  [ 1, -1, -1,     1, 1, 0, 1],     // 1
  [-1,  1, -1,     0, 1, 1, 1],     // 2
  [ 1,  1, -1,     0, 0, 1, 1],     // 3
  [-1,  1,  1,     1, 0.5, 0, 1],   // 4
  [1,  1,  1,      0.5, 1, 1, 1],   // 5
  [-1, -1,  1,     1, 0, 0.5, 1],   // 6
  [1, -1,  1,      0.5, 0, 1, 1],   // 7
];

var normals = [
  [0, 0, 1], [0, 1, 0], [0, 0, -1],
  [0, -1, 0], [-1, 0, 0], [1, 0, 0] ];

var indices = [
  [0, 1, 2,   1, 2, 3],
  [2, 3, 4,   3, 4, 5],
  [4, 5, 6,   5, 6, 7],
  [6, 7, 0,   7, 0, 1],
  [0, 2, 6,   2, 6, 4],
  [1, 3, 7,   3, 7, 5]
];

var attributes = []
for(let side=0; side < indices.length; ++side) {
    for(let vi=0; vi < indices[side].length; ++vi) {
        attributes.push(...vertices[indices[side][vi]]);
        attributes.push(...normals[side]);
    }
}

vertexCount = attributes.length / 10;

创建缓冲区并定义顶点属性的通用数组：

var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(attributes), gl.STATIC_DRAW);

var coords = gl.getAttribLocation(shaderProgram, "coords");
gl.vertexAttribPointer(coords, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, 0);
gl.enableVertexAttribArray(coords); 

var colorsLocation = gl.getAttribLocation(shaderProgram, "colors");
gl.vertexAttribPointer(colorsLocation, 4, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, Float32Array.BYTES_PER_ELEMENT * 3);
gl.enableVertexAttribArray(colorsLocation);

var normalLocation = gl.getAttribLocation(shaderProgram, "normal");
gl.vertexAttribPointer(normalLocation, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, Float32Array.BYTES_PER_ELEMENT * 7);
gl.enableVertexAttribArray(normalLocation);  

使用.drawArrays而非.drawElements绘制网格：

//gl.drawElements(gl.TRIANGLES, indexCount, gl.UNSIGNED_BYTE, 0);
gl.drawArrays(gl.TRIANGLES, 0, vertexCount);

---

请参见示例，其中我将建议应用于您的代码：

var gl,
    shaderProgram,
    vertices,
    matrix = mat4.create(),
    vertexCount,
    indexCount,
    q = quat.create(),
    translate =[-3, 0, -10],
    scale = [1,1,1],
    pivot = [0,0,0];
    
    translate2 = [0, 0, -8],
    scale2 = [3,3,3],
    pivot2 = [1,1,1]


initGL();
createShaders();
createVertices();
draw();

function initGL() {
  var canvas = document.getElementById("canvas");
  gl = canvas.getContext("webgl");
  gl.enable(gl.DEPTH_TEST);
  gl.viewport(0, 0, canvas.width, canvas.height);
  gl.clearColor(1, 1, 1, 1);
}

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

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

function createVertices() {
vertices = [
  [-1, -1, -1,     1, 0, 0, 1],     // 0
  [ 1, -1, -1,     1, 1, 0, 1],     // 1
  [-1,  1, -1,     0, 1, 1, 1],     // 2
  [ 1,  1, -1,     0, 0, 1, 1],     // 3
  [-1,  1,  1,     1, 0.5, 0, 1],   // 4
  [1,  1,  1,      0.5, 1, 1, 1],   // 5
  [-1, -1,  1,     1, 0, 0.5, 1],   // 6
  [1, -1,  1,      0.5, 0, 1, 1],   // 7
];

var normals = [
  [0, 0, 1], [0, 1, 0], [0, 0, -1],
  [0, -1, 0], [-1, 0, 0], [1, 0, 0] ];

var indices = [
  [0, 1, 2,   1, 2, 3],
  [2, 3, 4,   3, 4, 5],
  [4, 5, 6,   5, 6, 7],
  [6, 7, 0,   7, 0, 1],
  [0, 2, 6,   2, 6, 4],
  [1, 3, 7,   3, 7, 5]
];

var attributes = []
for(let side=0; side < indices.length; ++side) {
    for(let vi=0; vi < indices[side].length; ++vi) {
        attributes.push(...vertices[indices[side][vi]]);
        attributes.push(...normals[side]);
    }
}

  vertexCount = attributes.length / 10;

  var buffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(attributes), gl.STATIC_DRAW);

  var coords = gl.getAttribLocation(shaderProgram, "coords");
  gl.vertexAttribPointer(coords, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, 0);
  gl.enableVertexAttribArray(coords); 

  var colorsLocation = gl.getAttribLocation(shaderProgram, "colors");
  gl.vertexAttribPointer(colorsLocation, 4, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, Float32Array.BYTES_PER_ELEMENT * 3);
  gl.enableVertexAttribArray(colorsLocation);

  var normalLocation = gl.getAttribLocation(shaderProgram, "normal");
  gl.vertexAttribPointer(normalLocation, 3, gl.FLOAT, false, Float32Array.BYTES_PER_ELEMENT * 10, Float32Array.BYTES_PER_ELEMENT * 7);
  gl.enableVertexAttribArray(normalLocation);  
  
  gl.bindBuffer(gl.ARRAY_BUFFER, null);
  
  var lightColor = gl.getUniformLocation(shaderProgram, "lightColor");
  gl.uniform3f(lightColor, 1, 1, 1);
  
  var lightDirection = gl.getUniformLocation(shaderProgram, "lightDirection");
  gl.uniform3f(lightDirection, 0.5, 0.5, -1);


  var perspectiveMatrix = mat4.create();
  mat4.perspective(perspectiveMatrix, 1, canvas.width / canvas.height, 0.1, 11);
  var perspectiveLoc = gl.getUniformLocation(shaderProgram, "perspectiveMatrix");
  gl.uniformMatrix4fv(perspectiveLoc, false, perspectiveMatrix);

}

function draw(timeMs) {
  requestAnimationFrame(draw);

  let interval = timeMs / 3000
  let t = interval - Math.floor(interval); 

  let trans_t = vec3.lerp([], translate, translate2, t);
  let scale_t = vec3.lerp([], scale, scale2, t);
  let pivot_t = vec3.lerp([], pivot, pivot2, t);

  mat4.fromRotationTranslationScaleOrigin(matrix, q, trans_t, scale_t, pivot_t);

  var transformMatrix = gl.getUniformLocation(shaderProgram, "transformMatrix");
  gl.uniformMatrix4fv(transformMatrix, false, matrix);
  gl.clear(gl.COLOR_BUFFER_BIT);

  //gl.drawElements(gl.TRIANGLES, indexCount, gl.UNSIGNED_BYTE, 0);
  gl.drawArrays(gl.TRIANGLES, 0, vertexCount);
}


  /*
   * https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/Tutorial/Adding_2D_content_to_a_WebGL_context
   */
  function getShader(gl, id) {
    var shaderScript, theSource, currentChild, shader;

    shaderScript = document.getElementById(id);

    if (!shaderScript) {
      return null;
    }

    theSource = "";
    currentChild = shaderScript.firstChild;

    while (currentChild) {
      if (currentChild.nodeType == currentChild.TEXT_NODE) {
        theSource += currentChild.textContent;
      }

      currentChild = currentChild.nextSibling;
    }
    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 {
      // Unknown shader type
      return null;
    }
    gl.shaderSource(shader, theSource);

// Compile the shader program
    gl.compileShader(shader);

// See if it compiled successfully
    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
      alert("An error occurred compiling the shaders: " + gl.getShaderInfoLog(shader));
      return null;
    }

    return shader;
  }

<canvas id="canvas" width="600" height="600"></canvas>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/gl-matrix/2.3.2/gl-matrix-min.js"></script>

<script id="shader-vs" type="x-shader/x-vertex">
attribute vec4 coords;
uniform mat4 transformMatrix;
attribute vec3 normal;
attribute vec4 colors;
uniform vec3 lightColor;
uniform vec3 lightDirection;
varying vec4 varyingColors;
uniform mat4 perspectiveMatrix;
void main(void) {
    vec3 norm = normalize(normal);
    vec3 ld = normalize(lightDirection);
    float dotProduct = max(dot(norm, ld), 0.0);
    vec3 vertexColor = lightColor * colors.rgb * dotProduct;
    varyingColors = vec4(vertexColor, 1);
    gl_Position = perspectiveMatrix * transformMatrix  * coords;
}
</script>

<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
uniform vec4 color;
varying vec4 varyingColors;
void main(void) {
  gl_FragColor = varyingColors;
}
</script>