鸿蒙原生应用元服务开发-WebGL网页图形库开发着色器绘制彩色三角形

着色器绘制彩色三角形
使用WebGL开发时，为保证界面图形显示效果，请使用真机运行。
此场景为使用WebGL绘制的彩色三角形图形（GPU绘制）。开发示例如下：
创建页面布局。index.hml示例如下：

<div class="container">
<canvas ref="canvas1" style="width : 400px; height : 200px; background-color : lightyellow;"></canvas>
<button class="btn-button" onclick="BtnColorTriangle">BtnColorTriangle</button>
</div>

1.设置页面样式。index.css示例如下：

.container {flex-direction: column;justify-content: center;align-items: center;
}
.btn-button {margin: 1px;height: 40px;width: 220px;background-color: lightblue;font-size: 20px;text-color: blue;
}

2.编辑JavaScript代码文件，增加彩色三角形绘制逻辑代码。index.js示例如下：

// index.js// WebGL相关预定义
var gl = {DEPTH_BUFFER_BIT: 0x00000100,STENCIL_BUFFER_BIT: 0x00000400,COLOR_BUFFER_BIT: 0x00004000,POINTS: 0x0000,LINES: 0x0001,LINE_LOOP: 0x0002,LINE_STRIP: 0x0003,TRIANGLES: 0x0004,TRIANGLE_STRIP: 0x0005,TRIANGLE_FAN: 0x0006,ZERO: 0,ONE: 1,SRC_COLOR: 0x0300,ONE_MINUS_SRC_COLOR: 0x0301,SRC_ALPHA: 0x0302,ONE_MINUS_SRC_ALPHA: 0x0303,DST_ALPHA: 0x0304,ONE_MINUS_DST_ALPHA: 0x0305,DST_COLOR: 0x0306,ONE_MINUS_DST_COLOR: 0x0307,SRC_ALPHA_SATURATE: 0x0308,FUNC_ADD: 0x8006,BLEND_EQUATION: 0x8009,BLEND_EQUATION_RGB: 0x8009,BLEND_EQUATION_ALPHA: 0x883D,FUNC_SUBTRACT: 0x800A,FUNC_REVERSE_SUBTRACT: 0x800B,BLEND_DST_RGB: 0x80C8,BLEND_SRC_RGB: 0x80C9,BLEND_DST_ALPHA: 0x80CA,BLEND_SRC_ALPHA: 0x80CB,CONSTANT_COLOR: 0x8001,ONE_MINUS_CONSTANT_COLOR: 0x8002,CONSTANT_ALPHA: 0x8003,ONE_MINUS_CONSTANT_ALPHA: 0x8004,BLEND_COLOR: 0x8005,ARRAY_BUFFER: 0x8892,ELEMENT_ARRAY_BUFFER: 0x8893,ARRAY_BUFFER_BINDING: 0x8894,ELEMENT_ARRAY_BUFFER_BINDING: 0x8895,STREAM_DRAW: 0x88E0,STATIC_DRAW: 0x88E4,DYNAMIC_DRAW: 0x88E8,BUFFER_SIZE: 0x8764,BUFFER_USAGE: 0x8765,CURRENT_VERTEX_ATTRIB: 0x8626,FRONT: 0x0404,BACK: 0x0405,FRONT_AND_BACK: 0x0408,CULL_FACE: 0x0B44,BLEND: 0x0BE2,DITHER: 0x0BD0,STENCIL_TEST: 0x0B90,DEPTH_TEST: 0x0B71,SCISSOR_TEST: 0x0C11,POLYGON_OFFSET_FILL: 0x8037,SAMPLE_ALPHA_TO_COVERAGE: 0x809E,SAMPLE_COVERAGE: 0x80A0,NO_ERROR: 0,INVALID_ENUM: 0x0500,INVALID_VALUE: 0x0501,INVALID_OPERATION: 0x0502,OUT_OF_MEMORY: 0x0505,CW: 0x0900,CCW: 0x0901,LINE_WIDTH: 0x0B21,ALIASED_POINT_SIZE_RANGE: 0x846D,ALIASED_LINE_WIDTH_RANGE: 0x846E,CULL_FACE_MODE: 0x0B45,FRONT_FACE: 0x0B46,DEPTH_RANGE: 0x0B70,DEPTH_WRITEMASK: 0x0B72,DEPTH_CLEAR_VALUE: 0x0B73,DEPTH_FUNC: 0x0B74,STENCIL_CLEAR_VALUE: 0x0B91,STENCIL_FUNC: 0x0B92,STENCIL_FAIL: 0x0B94,STENCIL_PASS_DEPTH_FAIL: 0x0B95,STENCIL_PASS_DEPTH_PASS: 0x0B96,STENCIL_REF: 0x0B97,STENCIL_VALUE_MASK: 0x0B93,STENCIL_WRITEMASK: 0x0B98,STENCIL_BACK_FUNC: 0x8800,STENCIL_BACK_FAIL: 0x8801,STENCIL_BACK_PASS_DEPTH_FAIL: 0x8802,STENCIL_BACK_PASS_DEPTH_PASS: 0x8803,STENCIL_BACK_REF: 0x8CA3,STENCIL_BACK_VALUE_MASK: 0x8CA4,STENCIL_BACK_WRITEMASK: 0x8CA5,VIEWPORT: 0x0BA2,SCISSOR_BOX: 0x0C10,COLOR_CLEAR_VALUE: 0x0C22,COLOR_WRITEMASK: 0x0C23,UNPACK_ALIGNMENT: 0x0CF5,PACK_ALIGNMENT: 0x0D05,MAX_TEXTURE_SIZE: 0x0D33,MAX_VIEWPORT_DIMS: 0x0D3A,SUBPIXEL_BITS: 0x0D50,RED_BITS: 0x0D52,GREEN_BITS: 0x0D53,BLUE_BITS: 0x0D54,ALPHA_BITS: 0x0D55,DEPTH_BITS: 0x0D56,STENCIL_BITS: 0x0D57,POLYGON_OFFSET_UNITS: 0x2A00,POLYGON_OFFSET_FACTOR: 0x8038,TEXTURE_BINDING_2D: 0x8069,SAMPLE_BUFFERS: 0x80A8,SAMPLES: 0x80A9,RGBA8: 0x8058,SAMPLE_COVERAGE_VALUE: 0x80AA,SAMPLE_COVERAGE_INVERT: 0x80AB,COMPRESSED_TEXTURE_FORMATS: 0x86A3,DONT_CARE: 0x1100,FASTEST: 0x1101,NICEST: 0x1102,GENERATE_MIPMAP_HINT: 0x8192,BYTE: 0x1400,UNSIGNED_BYTE: 0x1401,SHORT: 0x1402,UNSIGNED_SHORT: 0x1403,INT: 0x1404,UNSIGNED_INT: 0x1405,FLOAT: 0x1406,DEPTH_COMPONENT: 0x1902,ALPHA: 0x1906,RGB: 0x1907,RGBA: 0x1908,LUMINANCE: 0x1909,LUMINANCE_ALPHA: 0x190A,UNSIGNED_SHORT_4_4_4_4: 0x8033,UNSIGNED_SHORT_5_5_5_1: 0x8034,UNSIGNED_SHORT_5_6_5: 0x8363,FRAGMENT_SHADER: 0x8B30,VERTEX_SHADER: 0x8B31,MAX_VERTEX_ATTRIBS: 0x8869,MAX_VERTEX_UNIFORM_VECTORS: 0x8DFB,MAX_VARYING_VECTORS: 0x8DFC,MAX_COMBINED_TEXTURE_IMAGE_UNITS: 0x8B4D,MAX_VERTEX_TEXTURE_IMAGE_UNITS: 0x8B4C,MAX_TEXTURE_IMAGE_UNITS: 0x8872,MAX_FRAGMENT_UNIFORM_VECTORS: 0x8DFD,SHADER_TYPE: 0x8B4F,DELETE_STATUS: 0x8B80,LINK_STATUS: 0x8B82,VALIDATE_STATUS: 0x8B83,ATTACHED_SHADERS: 0x8B85,ACTIVE_UNIFORMS: 0x8B86,ACTIVE_ATTRIBUTES: 0x8B89,SHADING_LANGUAGE_VERSION: 0x8B8C,CURRENT_PROGRAM: 0x8B8D,NEVER: 0x0200,LESS: 0x0201,EQUAL: 0x0202,LEQUAL: 0x0203,GREATER: 0x0204,NOTEQUAL: 0x0205,GEQUAL: 0x0206,ALWAYS: 0x0207,KEEP: 0x1E00,REPLACE: 0x1E01,INCR: 0x1E02,DECR: 0x1E03,INVERT: 0x150A,INCR_WRAP: 0x8507,DECR_WRAP: 0x8508,VENDOR: 0x1F00,RENDERER: 0x1F01,VERSION: 0x1F02,NEAREST: 0x2600,LINEAR: 0x2601,NEAREST_MIPMAP_NEAREST: 0x2700,LINEAR_MIPMAP_NEAREST: 0x2701,NEAREST_MIPMAP_LINEAR: 0x2702,LINEAR_MIPMAP_LINEAR: 0x2703,TEXTURE_MAG_FILTER: 0x2800,TEXTURE_MIN_FILTER: 0x2801,TEXTURE_WRAP_S: 0x2802,TEXTURE_WRAP_T: 0x2803,TEXTURE_2D: 0x0DE1,TEXTURE: 0x1702,TEXTURE_CUBE_MAP: 0x8513,TEXTURE_BINDING_CUBE_MAP: 0x8514,TEXTURE_CUBE_MAP_POSITIVE_X: 0x8515,TEXTURE_CUBE_MAP_NEGATIVE_X: 0x8516,TEXTURE_CUBE_MAP_POSITIVE_Y: 0x8517,TEXTURE_CUBE_MAP_NEGATIVE_Y: 0x8518,TEXTURE_CUBE_MAP_POSITIVE_Z: 0x8519,TEXTURE_CUBE_MAP_NEGATIVE_Z: 0x851A,MAX_CUBE_MAP_TEXTURE_SIZE: 0x851C,TEXTURE0: 0x84C0,TEXTURE1: 0x84C1,TEXTURE2: 0x84C2,TEXTURE3: 0x84C3,TEXTURE4: 0x84C4,TEXTURE5: 0x84C5,TEXTURE6: 0x84C6,TEXTURE7: 0x84C7,TEXTURE8: 0x84C8,TEXTURE9: 0x84C9,TEXTURE10: 0x84CA,TEXTURE11: 0x84CB,TEXTURE12: 0x84CC,TEXTURE13: 0x84CD,TEXTURE14: 0x84CE,TEXTURE15: 0x84CF,TEXTURE16: 0x84D0,TEXTURE17: 0x84D1,TEXTURE18: 0x84D2,TEXTURE19: 0x84D3,TEXTURE20: 0x84D4,TEXTURE21: 0x84D5,TEXTURE22: 0x84D6,TEXTURE23: 0x84D7,TEXTURE24: 0x84D8,TEXTURE25: 0x84D9,TEXTURE26: 0x84DA,TEXTURE27: 0x84DB,TEXTURE28: 0x84DC,TEXTURE29: 0x84DD,TEXTURE30: 0x84DE,TEXTURE31: 0x84DF,ACTIVE_TEXTURE: 0x84E0,REPEAT: 0x2901,CLAMP_TO_EDGE: 0x812F,MIRRORED_REPEAT: 0x8370,FLOAT_VEC2: 0x8B50,FLOAT_VEC3: 0x8B51,FLOAT_VEC4: 0x8B52,INT_VEC2: 0x8B53,INT_VEC3: 0x8B54,INT_VEC4: 0x8B55,BOOL: 0x8B56,BOOL_VEC2: 0x8B57,BOOL_VEC3: 0x8B58,BOOL_VEC4: 0x8B59,FLOAT_MAT2: 0x8B5A,FLOAT_MAT3: 0x8B5B,FLOAT_MAT4: 0x8B5C,SAMPLER_2D: 0x8B5E,SAMPLER_CUBE: 0x8B60,VERTEX_ATTRIB_ARRAY_ENABLED: 0x8622,VERTEX_ATTRIB_ARRAY_SIZE: 0x8623,VERTEX_ATTRIB_ARRAY_STRIDE: 0x8624,VERTEX_ATTRIB_ARRAY_TYPE: 0x8625,VERTEX_ATTRIB_ARRAY_NORMALIZED: 0x886A,VERTEX_ATTRIB_ARRAY_POINTER: 0x8645,VERTEX_ATTRIB_ARRAY_BUFFER_BINDING: 0x889F,IMPLEMENTATION_COLOR_READ_TYPE: 0x8B9A,IMPLEMENTATION_COLOR_READ_FORMAT: 0x8B9B,COMPILE_STATUS: 0x8B81,LOW_FLOAT: 0x8DF0,MEDIUM_FLOAT: 0x8DF1,HIGH_FLOAT: 0x8DF2,LOW_INT: 0x8DF3,MEDIUM_INT: 0x8DF4,HIGH_INT: 0x8DF5,FRAMEBUFFER: 0x8D40,RENDERBUFFER: 0x8D41,RGBA4: 0x8056,RGB5_A1: 0x8057,RGB565: 0x8D62,DEPTH_COMPONENT16: 0x81A5,STENCIL_INDEX8: 0x8D48,DEPTH_STENCIL: 0x84F9,RENDERBUFFER_WIDTH: 0x8D42,RENDERBUFFER_HEIGHT: 0x8D43,RENDERBUFFER_INTERNAL_FORMAT: 0x8D44,RENDERBUFFER_RED_SIZE: 0x8D50,RENDERBUFFER_GREEN_SIZE: 0x8D51,RENDERBUFFER_BLUE_SIZE: 0x8D52,RENDERBUFFER_ALPHA_SIZE: 0x8D53,RENDERBUFFER_DEPTH_SIZE: 0x8D54,RENDERBUFFER_STENCIL_SIZE: 0x8D55,FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE: 0x8CD0,FRAMEBUFFER_ATTACHMENT_OBJECT_NAME: 0x8CD1,FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL: 0x8CD2,FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE: 0x8CD3,COLOR_ATTACHMENT0: 0x8CE0,DEPTH_ATTACHMENT: 0x8D00,STENCIL_ATTACHMENT: 0x8D20,DEPTH_STENCIL_ATTACHMENT: 0x821A,NONE: 0,FRAMEBUFFER_COMPLETE: 0x8CD5,FRAMEBUFFER_INCOMPLETE_ATTACHMENT: 0x8CD6,FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: 0x8CD7,FRAMEBUFFER_INCOMPLETE_DIMENSIONS: 0x8CD9,FRAMEBUFFER_UNSUPPORTED: 0x8CDD,FRAMEBUFFER_BINDING: 0x8CA6,RENDERBUFFER_BINDING: 0x8CA7,MAX_RENDERBUFFER_SIZE: 0x84E8,INVALID_FRAMEBUFFER_OPERATION: 0x0506,UNPACK_FLIP_Y_WEBGL: 0x9240,UNPACK_PREMULTIPLY_ALPHA_WEBGL: 0x9241,CONTEXT_LOST_WEBGL: 0x9242,UNPACK_COLORSPACE_CONVERSION_WEBGL: 0x9243,BROWSER_DEFAULT_WEBGL: 0x9244,TEXTURE_MAX_LOD: 0x813B,TEXTURE_BASE_LEVEL: 0x813C,TEXTURE_IMMUTABLE_FORMAT: 0x912F,UNIFORM_BLOCK_BINDING: 0x8A3F,UNIFORM_BLOCK_DATA_SIZE: 0x8A40,UNIFORM_BLOCK_ACTIVE_UNIFORMS: 0x8A42,UNIFORM_BLOCK_ACTIVE_UNIFORM_INDICES: 0x8A43,UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER: 0x8A44,UNIFORM_BLOCK_REFERENCED_BY_FRAGMENT_SHADER: 0x8A46,RED: 0x1903,PIXEL_UNPACK_BUFFER: 0x88EC,RGB8: 0x8051,R16F: 0x822D,COPY_WRITE_BUFFER: 0x8F37,TEXTURE_3D: 0x806F,COMPRESSED_R11_EAC: 0x9270,COPY_READ_BUFFER: 0x8F36,TRANSFORM_FEEDBACK_BUFFER: 0x8C8E,TRANSFORM_FEEDBACK_BUFFER_BINDING: 0x8C8F,TRANSFORM_FEEDBACK_BUFFER_SIZE: 0x8C85,TRANSFORM_FEEDBACK_BUFFER_START: 0x8C84,UNIFORM_BUFFER_BINDING: 0x8A28,UNIFORM_BUFFER_SIZE: 0x8A2A,UNIFORM_BUFFER_START: 0x8A29,DYNAMIC_READ: 0x88E9,READ_FRAMEBUFFER: 0x8CA8,COLOR_ATTACHMENT1: 0x8CE1,INTERLEAVED_ATTRIBS: 0x8C8C,UNIFORM_OFFSET: 0x8A3B,UNIFORM_TYPE: 0x8A37,UNIFORM_SIZE: 0x8A38,UNIFORM_BLOCK_INDEX: 0x8A3A,UNIFORM_ARRAY_STRIDE: 0x8A3C,UNIFORM_MATRIX_STRIDE: 0x8A3D,UNIFORM_IS_ROW_MAJOR: 0x8A3E,TEXTURE_MAX_ANISOTROPY_EXT: 0x84FE
}// 顶点着色器程序
var VSHADER_SOURCE ='attribute vec4 a_Position;\n' + // attribute variable'attribute vec4 a_Color;\n' +'varying vec4 v_Color;\n' +'void main() {\n' +'  gl_Position = a_Position;\n' + // Set the vertex coordinates of the point'  v_Color = a_Color;\n' +'}\n';// 片元着色器程序
var FSHADER_SOURCE ='precision mediump float;\n' +'varying vec4 v_Color;\n' +'void main() {\n' +'  gl_FragColor = v_Color;\n' +'}\n';function initVertexBuffers(gl) {// 顶点坐标和颜色var verticesColors = new Float32Array([0.0, -0.5, 1.0, 0.0, 0.0,-0.5, -0.8, 0.0, 1.0, 0.0,0.5, -0.8, 0.0, 0.0, 1.0,]);var n = 3; // 点的个数var FSIZE = verticesColors.BYTES_PER_ELEMENT; //数组中每个元素的字节数// 创建缓冲区对象var vertexBuffer = gl.createBuffer();if (!vertexBuffer) {console.log('Failed to create the buffer object');return -1;}// 将缓冲区对象绑定到目标gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);// 向缓冲区对象写入数据gl.bufferData(gl.ARRAY_BUFFER, verticesColors.buffer, gl.STATIC_DRAW);// 获取着色器中attribute变量a_Position的地址var a_Position = gl.getAttribLocation(gl.program, 'a_Position');if (a_Position < 0) {console.log('Failed to get the storage location of a_Position');return -1;}// 将缓冲区对象分配给a_Position变量gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 5 * FSIZE, 0);// 连接a_Position变量与分配给它的缓冲区对象gl.enableVertexAttribArray(a_Position);// 获取着色器中attribute变量a_Color的地址var a_Color = gl.getAttribLocation(gl.program, 'a_Color');if (a_Color < 0) {console.log('Failed to get the storage location of a_Color');return -1;}// 将缓冲区对象分配给a_Color变量gl.vertexAttribPointer(a_Color, 3, gl.FLOAT, false, FSIZE * 5, FSIZE * 2);// 连接a_Color变量与分配给它的缓冲区对象gl.enableVertexAttribArray(a_Color);// 解除绑定gl.bindBuffer(gl.ARRAY_BUFFER, null);return n;
}/*** 创建并使能一个program对象* @param gl 表示 WebGL上下文对* @param vshader 表示顶点着色器* @param fshader 表示片段着色器* @return 如果WebGLProgram对象被创建并成功作为当前对象，则返回true；否则返回false */
function initShaders(gl, vshader, fshader) {var program = createProgram(gl, vshader, fshader);console.log("======createProgram program: " + program);if (!program) {console.log('Failed to create program');return false;}gl.useProgram(program);gl.program = program;return true;
}/*** 创建一个linked program对象* @param gl 表示 WebGL上下文对象* @param vshader 表示顶点着色器* @param fshader 表示片段着色器* @return 如果创建program成功，则返回创建的program；否则返回null*/
function createProgram(gl, vshader, fshader) {console.log("======createProgram start======");// 创建shader对象var vertexShader = loadShader(gl, gl.VERTEX_SHADER, vshader);console.log("======vertexShader: " + vertexShader);var fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fshader);if (!vertexShader || !fragmentShader) {return null;}// 创建program对象var program = gl.createProgram();console.log("======createProgram program: " + program);if (!program) {return null;}// 将着色器附加到对象gl.attachShader(program, vertexShader);gl.attachShader(program, fragmentShader);// 连接程序对象gl.linkProgram(program);// 检查连接对象的结果var linked = gl.getProgramParameter(program, 0x8B82);console.log("======getProgramParameter linked: " + linked);if (!linked) {var error = gl.getProgramInfoLog(program);console.log('Failed to link the program: ' + error);gl.deleteProgram(program);gl.deleteShader(fragmentShader);gl.deleteShader(vertexShader);return null;}return program;
}/*** 创建一个shader对象* @param gl 表示 WebGL上下文对象* @param type 表示shader类型* @param source 表示shader的源码 * @return 如果操作成功，返回创建的着色器对象；否则返回false*/ 
function loadShader(gl, type, source) {console.log("======into loadShader====");// 创建shader对象var shader = gl.createShader(type);if (shader == null) {console.log('Failed to create the shader.');return null;}// 设置shader programgl.shaderSource(shader, source);// 编译shadergl.compileShader(shader);// 检查shader编译结果var compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS);if (!compiled) {var error = gl.getShaderInfoLog(shader);console.log('Failed to compile the shader: ' + error);gl.deleteShader(shader);return null;}return shader;
}export default {data: {title: "DEMO BY TEAMOL",fit:"cover",fits: ["cover", "contain", "fill", "none", "scale-down"]},onInit() {this.title = this.$t('strings.world');},BtnColorTriangle() {// 获取canvas元素const el = this.$refs.canvas1;// 获取webgl上下文var gl = el.getContext('webgl');if (!gl) {console.log('Failed to get the rendering context for WebGL');return;}// 初始化着色器if (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) {console.log('Failed to initialize shaders.');return;}// 设置顶点位置var n = initVertexBuffers(gl);if (n < 0) {console.log('Failed to set the positions of the vertices');return;}// 指定清空<canvas>的颜色gl.clearColor(0.0, 0.0, 0.0, 1.0);// 清空<canvas>gl.clear(gl.COLOR_BUFFER_BIT);// 绘制三角形gl.drawArrays(gl.TRIANGLES, 0, n);// 清buffergl.flush();}
}

3.点击按钮绘制彩色三角形的效果图

鸿蒙原生应用元服务开发-WebGL网页图形库开发着色器绘制彩色三角形-鸿蒙开发者社区