2

我最近学习opengl es 2.0，现在我尝试对自己生成的三角形进行高斯模糊。我在网上有一些难以理解的例子，大多数都在图像上应用了模糊。我知道我必须使用帧缓冲区，但我不知道如何在此上绘制三角形并应用模糊。是否有可能在 C++ 中看到具有良好解释的真实完整代码？

编辑 ：

#include <stdio.h>
#include <stdlib.h>
#include <iostream>

#define GLFW_INCLUDE_ES2
#include <GLFW/glfw3.h>
#include "shaders.hpp"
#include "camera.hpp"

unsigned int vbo, cbo, tbo;
GLuint _fbo, _fbo2, _tex, _tex2;


static const GLuint WIDTH = 800;
static const GLuint HEIGHT = 600;
GLuint pos, col, tex, normal;
camera * _camera = new camera();

static const GLfloat vertices[] = {
  0.0f,  1.0f, 0.0f,
  1.0f, -1.0f, 0.0f,
  -1.0f, -1.0f, 0.0f
};

static const GLfloat colors[] = {
  0.0f,  0.5f, 1.0f,
  0.5f,  0.5f, 1.0f,
  0.5f,  0.5f, 1.0f
};

static const GLfloat texture[] = {
  1.0f, 1.0f,
  1.0f, 0.0f,
  0.0f, 1.0f
};

int main(void){
  GLFWwindow* window;
  shaders * shaderBasic;
  GLuint pId;

  glm::mat4 projection; static glm::mat4 view; static glm::mat4 model;

  glfwInit();
  glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
  window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
  glfwMakeContextCurrent(window);

  printf("GL_VERSION  : %s\n", glGetString(GL_VERSION) );
  printf("GL_RENDERER : %s\n", glGetString(GL_RENDERER) );

  std::string vs, fs;
  vs = "basic.vs";
  fs = "basic.fs";
  shaderBasic = new shaders(vs, fs);
  shaderBasic->CompileShader();
  shaderBasic->LinkShader();
  pId = shaderBasic->getProgramId();

  pos = glGetAttribLocation(pId, "position");
  col = glGetAttribLocation(pId, "colors");
  tex = glGetAttribLocation(pId, "tex");

  fs = "lastBlur.fs";
  shaders * blurShader;
  GLuint pIdBlur;
  blurShader = new shaders(vs, fs);
  blurShader->CompileShader();
  blurShader->LinkShader();
  pIdBlur = blurShader->getProgramId();

  _camera->setPositionCamera(glm::vec3(0, 0, -1));
  _camera->setLookAtCamera(glm::vec3(0, 0, 0));
  _camera->setFieldOfView(45);
  _camera->setAspect(WIDTH, HEIGHT);
  _camera->setViewport(WIDTH, HEIGHT);
  _camera->getMatricies(projection, view, model);

  glGenFramebuffers(1, &_fbo);
  glGenTextures(1, &_tex);
  glBindFramebuffer(GL_FRAMEBUFFER, _fbo);
  glBindTexture(GL_TEXTURE_2D, _tex);
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WIDTH/2, HEIGHT/2, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _tex, 0);
  glBindTexture(GL_TEXTURE_2D, 0);
  glBindFramebuffer(GL_FRAMEBUFFER, 0);

  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << std::endl;
  else{
    std::cout << "FRAMEBUFFER COMPLETE" << std::endl;
  }
  auto sampTex = glGetUniformLocation(pIdBlur, "texture0");
  std::cerr << "sampTex : " << sampTex << std::endl;
  glUniform1i(sampTex, 0);  
  while (!glfwWindowShouldClose(window)) {
    //    glViewport(0, 0, WIDTH, HEIGHT);

    glBindFramebuffer(GL_FRAMEBUFFER, _fbo);
    glClearColor(0.0f, 0.0f, 0.4f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    //    glViewport(0, 0, WIDTH/2, HEIGHT/2);
    glUseProgram(pIdBlur);
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(pos, 3, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(pos);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glGenBuffers(1, &cbo);
    glBindBuffer(GL_ARRAY_BUFFER, cbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);
    glVertexAttribPointer(col, 2, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(col);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glGenBuffers(1, &tbo);
    glBindBuffer(GL_ARRAY_BUFFER, tbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(texture), texture, GL_STATIC_DRAW);
    glVertexAttribPointer(tex, 2, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(tex);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glDrawArrays(GL_TRIANGLES, 0, 3);


    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glUseProgram(pId);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, _tex);
    glDrawArrays(GL_TRIANGLES, 0, 3);    

    glfwPollEvents();
    glfwSwapBuffers(window);
  }
  glDeleteBuffers(1, &vbo);
  glfwTerminate();
  return EXIT_SUCCESS;
}

模糊着色器：

#version 100
precision mediump float;

uniform sampler2D texture0;
varying vec3 vColor;
varying vec2 TexCoords;

vec4 blur13(sampler2D image, vec2 uv, vec2 resolution, vec2 direction) {
    vec4 color = vec4(0.0);
    vec2 off1 = vec2(1.411764705882353) * direction;
    vec2 off2 = vec2(3.2941176470588234) * direction;
    vec2 off3 = vec2(5.176470588235294) * direction;
    color += texture2D(image, uv) * 0.1964825501511404;
    color += texture2D(image, uv + (off1 / resolution)) * 0.2969069646728344;
    color += texture2D(image, uv - (off1 / resolution)) * 0.2969069646728344;
    color += texture2D(image, uv + (off2 / resolution)) * 0.09447039785044732;
    color += texture2D(image, uv - (off2 / resolution)) * 0.09447039785044732;
    color += texture2D(image, uv + (off3 / resolution)) * 0.010381362401148057;
    color += texture2D(image, uv - (off3 / resolution)) * 0.010381362401148057;
    return color;
}

void main(){
    gl_FragColor = blur13(texture0, TexCoords, vec2(400, 300), vec2(1.0, 0.0));
}
4

2 回答 2

3

我假设你已经交换了pIdBlur和pId。

我将向您介绍具有 2 个通道的高斯模糊着色器。这是一个近似值，它首先在第 1 遍中沿 X 轴模糊，在第 2 遍中沿 Y 轴模糊。这为强模糊带来了更好的性能。模糊着色器使用正态（或高斯）分布。对于 2 个通道，使用相同的着色器程序，2 个通道具有单独的方向设置，存储在 uniform 中vec2 u_dir。模糊效果的强度可以随着float u_sigma[0.0, 1.0] 范围内的 uniform 变量而变化。

模糊顶点着色器

precision mediump float;
attribute vec2 inPos;
varying   vec2 pos;

void main()
{
    pos = inPos;
    gl_Position = vec4( inPos, 0.0, 1.0 );
}

模糊片段着色器

precision mediump float;
varying vec2 pos;

uniform sampler2D u_texture;
uniform vec2      u_textureSize;
uniform float     u_sigma;
uniform vec2      u_dir;

float CalcGauss( float x, float sigma )
{
    if ( sigma <= 0.0 )
        return 0.0;
    return exp( -(x*x) / (2.0 * sigma) ) / (2.0 * 3.14157 * sigma);
}

void main()
{
    vec2 texC     = pos.st * 0.5 + 0.5;
    vec4 texCol   = texture2D( u_texture, texC );
    vec4 gaussCol = vec4( texCol.rgb, 1.0 );
    vec2 step     = u_dir / u_textureSize;
    for ( int i = 1; i <= 32; ++ i )
    {
        float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );
        if ( weight < 1.0/255.0 )
            break;
        texCol    = texture2D( u_texture, texC + step * float(i) );
        gaussCol += vec4( texCol.rgb * weight, weight );
        texCol    = texture2D( u_texture, texC - step * float(i) );
        gaussCol += vec4( texCol.rgb * weight, weight );
    }
    gaussCol.rgb = clamp( gaussCol.rgb / gaussCol.w, 0.0, 1.0 );
    gl_FragColor = vec4( gaussCol.rgb, 1.0 );
}

程序链接后，可以从以下位置读取统一位置和属性索引：

GLint attrInxPos = glGetAttribLocation( pIdBlur, "inPos" );
GLint locTexture = glGetUniformLocation( pIdBlur, "u_texture" );
GLint locTexSize = glGetUniformLocation( pIdBlur, "u_textureSize" );
GLint locSigma   = glGetUniformLocation( pIdBlur, "u_sigma" );
GLint locDir     = glGetUniformLocation( pIdBlur, "u_dir" );

必须创建一个顶点数组对象，其中包含一个四边形，稍后将在整个视口上绘制，用于屏幕空间模糊通道：

GLuint screenVAO;
glGenVertexArrays( 1, &screenVAO );
glBindVertexArray( screenVAO );
GLuint quadBuf;
glGenBuffers( 1, &quadBuf );
glBindBuffer( GL_ARRAY_BUFFER, quadBuf );
GLfloat screenRect[] = { -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f };
glBufferData( GL_ARRAY_BUFFER, 8 * sizeof( float ), screenRect, GL_STATIC_DRAW );
glEnableVertexAttribArray( attrInxPos );
glVertexAttribPointer( attrInxPos, 2, GL_FLOAT, GL_FALSE, 0, nullptr );

必须创建 2 个帧缓冲区，纹理附加到其颜色平面。在第一个中，场景被绘制。第二个由第一个模糊通道使用。第二个模糊通道直接绘制到绘图缓冲区。

GLuint texObj[2];
GLuint fbObj[2];
glGenTextures(2, texObj);
glGenFramebuffers(2, fbObj);
glActiveTexture(GL_TEXTURE0);
for ( int i = 0; i < 2; i ++ )
{
    glBindTexture(GL_TEXTURE_2D, texObj[i]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
    glBindFramebuffer(GL_FRAMEBUFFER, fbObj[i]);
    glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texObj[i], 0 );
    GLuint renderbuffer;
    glGenRenderbuffers(1, &renderbuffer);
    glBindRenderbuffer( GL_RENDERBUFFER, renderbuffer );
    glRenderbufferStorage( GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height );
    glFramebufferRenderbuffer( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderbuffer );
}
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

现在已经生成了模糊通道所需的一切。

要绘制和模糊场景，必须应用以下步骤。首先，您必须绑定并清除第一个帧缓冲区

glBindFramebuffer(GL_FRAMEBUFFER, fbObj[0]);
glClearColor(0.0f, 0.0f, 0.4f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

并使用着色器程序绘制对象：

glUseProgram(pId);

现在绘制场景的对象。

.....
glDrawArrays(GL_TRIANGLES, 0, 3);

第二步是第一个模糊通道。必须使用模糊程序，并且必须绑定第二帧缓冲区。释放第一帧缓冲区后，您可以使用附加到其颜色平面的纹理作为模糊着色器的输入。
请注意，纹理不能同时作为源和目标，这会导致未定义的行为。
要将纹理绑定到着色器，您必须将纹理绑定到纹理单元并将纹理单元的索引分配给着色器的统一采样器。

int texUnitIndex = 1;
GLfloat texSize  = { width, height };
GLfloat dirX[]   = { 1.0f, 0.0f };  
GLfloat sigma    = .....; // 0.0 <= sigma <= 1.0

glBindFramebuffer(GL_FRAMEBUFFER, fbObj[1]);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(pIdBlur);
glActiveTexture(GL_TEXTURE0 + texUnitIndex);
glBindTexture(GL_TEXTURE_2D, texObj[0]);
glUniform1i(locTexture, texUnitIndex); 
glUniform2fv(locTexSize, texSize);
glUniform2fv(locTexSize, dirX);
glUniform1f(locTexSize, sigma);

要应用模糊通道，必须绘制视口区域的四边形。

glBindVertexArray( screenVAO );
glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );

第二个也是最后一个模糊通道，类似于第一个模糊通道。第一个模糊通道的目标纹理是源纹理，目标是绘图缓冲区。必须为视口的 Y 轴设置模糊方向。

GLfloat dirY[] = { 0.0f, 1.0f }; 

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindTexture(GL_TEXTURE_2D, texObj[1]);
glUniform2fv(locTexSize, dirY);

另请参阅以下问题的答案：

参见类似的 WebGL 示例：

(function loadscene() {

var resize, gl, progDraw, progBlur, vp_size, blurFB;
var canvas, camera, bufCube = {}, bufQuad = {}; 
var shininess = 10.0, glow = 10.0, sigma = 0.8, radius = 1.0;

function render(deltaMS){

  var sliderScale = 100;
  sigma  = document.getElementById( "sigma" ).value / sliderScale;
  radius = document.getElementById( "radius" ).value / sliderScale;

  vp_size = [canvas.width, canvas.height];
  camera.Update( vp_size );
      
  gl.enable( gl.DEPTH_TEST );
  gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
  gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );

  // set up framebuffer
  gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[0] );
  gl.viewport( 0, 0, blurFB[0].width, blurFB[0].height );
  gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );

  // setup view projection and model
  var prjMat = camera.Perspective();
  var viewMat = camera.LookAt();
  var modelMat = RotateAxis( IdentM44(), Fract( deltaMS / 13000.0 ) * 2.0 * Math.PI, 0 );
  modelMat = RotateAxis( modelMat, Fract( deltaMS / 17000.0 ) * 2.0 * Math.PI, 1 );
  
  // set up draw shader
  ShProg.Use( progDraw );
  ShProg.SetM44( progDraw, "u_projectionMat44", prjMat );
  ShProg.SetM44( progDraw, "u_modelViewMat44", Multiply(viewMat, modelMat) );
  ShProg.SetF1( progDraw, "u_shininess", shininess );
  
  // draw scene
  VertexBuffer.Draw( bufCube );

  // set blur-X framebuffer and bind frambuffer texture
  gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[1] );
  gl.viewport( 0, 0, blurFB[1].width, blurFB[1].height );
  gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
  var texUnit = 1;
  gl.activeTexture( gl.TEXTURE0 + texUnit );
  gl.bindTexture( gl.TEXTURE_2D, blurFB[0].color0_texture );

  // set up blur-X shader
  ShProg.Use( progBlur );
  ShProg.SetI1( progBlur, "u_texture", texUnit )
  ShProg.SetF2( progBlur, "u_textureSize", vp_size );
  ShProg.SetF1( progBlur, "u_sigma", sigma )
  ShProg.SetF1( progBlur, "u_radius", radius )
  ShProg.SetF2( progBlur, "u_dir", [1.0, 0.0] )

  // draw full screen space
  gl.enableVertexAttribArray( progBlur.inPos );
  gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
  gl.vertexAttribPointer( progBlur.inPos, 2, gl.FLOAT, false, 0, 0 ); 
  gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
  gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );
  gl.disableVertexAttribArray( progBlur.inPos );

  // reset framebuffer and bind frambuffer texture
  gl.bindFramebuffer( gl.FRAMEBUFFER, null );
  gl.viewport( 0, 0, vp_size[0], vp_size[1] );
  gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
  texUnit = 2;
  gl.activeTexture( gl.TEXTURE0 + texUnit );
  gl.bindTexture( gl.TEXTURE_2D, blurFB[1].color0_texture );

  // set up pst process shader
  ShProg.SetI1( progBlur, "u_texture", texUnit )
  ShProg.SetF1( progBlur, "u_radius", radius )
  ShProg.SetF2( progBlur, "u_dir", [0.0, 1.0] )

  // draw full screen space
  gl.enableVertexAttribArray( progBlur.inPos );
  gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
  gl.vertexAttribPointer( progBlur.inPos, 2, gl.FLOAT, false, 0, 0 ); 
  gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
  gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );
  gl.disableVertexAttribArray( progBlur.inPos );

  requestAnimationFrame(render);
}

function initScene() {

  canvas = document.getElementById( "canvas");
  gl = canvas.getContext( "experimental-webgl" );
  if ( !gl )
      return null;

  progDraw = ShProg.Create( 
  [ { source : "draw-shader-vs", stage : gl.VERTEX_SHADER },
      { source : "draw-shader-fs", stage : gl.FRAGMENT_SHADER }
  ] );
  if ( !progDraw.progObj )
      return null;
  progDraw.inPos = gl.getAttribLocation( progDraw.progObj, "inPos" );
  progDraw.inNV  = gl.getAttribLocation( progDraw.progObj, "inNV" );
  progDraw.inCol = gl.getAttribLocation( progDraw.progObj, "inCol" );

  progBlur = ShProg.Create( 
  [ { source : "post-shader-vs", stage : gl.VERTEX_SHADER },
      { source : "blur-shader-fs", stage : gl.FRAGMENT_SHADER }
  ] );
  progBlur.inPos = gl.getAttribLocation( progBlur.progObj, "inPos" );
  if ( !progBlur.progObj )
      return;    
  
  // create cube
  var cubePos = [
  -1.0, -1.0,  1.0,  1.0, -1.0,  1.0,  1.0,  1.0,  1.0, -1.0,  1.0,  1.0,
  -1.0, -1.0, -1.0,  1.0, -1.0, -1.0,  1.0,  1.0, -1.0, -1.0,  1.0, -1.0 ];
  var cubeCol = [ 1.0, 0.0, 0.0, 1.0, 0.5, 0.0, 1.0, 0.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0 ];
  var cubeHlpInx = [ 0, 1, 2, 3, 1, 5, 6, 2, 5, 4, 7, 6, 4, 0, 3, 7, 3, 2, 6, 7, 1, 0, 4, 5 ];  
  var cubePosData = [];
  for ( var i = 0; i < cubeHlpInx.length; ++ i ) {
  cubePosData.push( cubePos[cubeHlpInx[i]*3], cubePos[cubeHlpInx[i]*3+1], cubePos[cubeHlpInx[i]*3+2] );
  }
  var cubeNVData = [];
  for ( var i1 = 0; i1 < cubeHlpInx.length; i1 += 4 ) {
  var nv = [0, 0, 0];
  for ( i2 = 0; i2 < 4; ++ i2 ) {
      var i = i1 + i2;
      nv[0] += cubePosData[i*3]; nv[1] += cubePosData[i*3+1]; nv[2] += cubePosData[i*3+2];
  }
  for ( i2 = 0; i2 < 4; ++ i2 )
  cubeNVData.push( nv[0], nv[1], nv[2] );
  }
  var cubeColData = [];
  for ( var is = 0; is < 6; ++ is ) {
  for ( var ip = 0; ip < 4; ++ ip ) {
      cubeColData.push( cubeCol[is*3], cubeCol[is*3+1], cubeCol[is*3+2] ); 
  }
  }
  var cubeInxData = [];
  for ( var i = 0; i < cubeHlpInx.length; i += 4 ) {
  cubeInxData.push( i, i+1, i+2, i, i+2, i+3 );   
  }
  bufCube = VertexBuffer.Create(
  [ { data : cubePosData, attrSize : 3, attrLoc : progDraw.inPos },
  { data : cubeNVData,  attrSize : 3, attrLoc : progDraw.inNV },
  { data : cubeColData, attrSize : 3, attrLoc : progDraw.inCol } ],
  cubeInxData );

  bufQuad.pos = gl.createBuffer();
  gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
  gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( [ -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0 ] ), gl.STATIC_DRAW );
  bufQuad.inx = gl.createBuffer();
  gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
  gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( [ 0, 1, 2, 0, 2, 3 ] ), gl.STATIC_DRAW );  
  
  camera = new Camera( [0, 3, 0.0], [0, 0, 0], [0, 0, 1], 90, vp_size, 0.5, 100 );

  window.onresize = resize;
  resize();
  requestAnimationFrame(render);
}

function resize() {
  //vp_size = [gl.drawingBufferWidth, gl.drawingBufferHeight];
  vp_size = [window.innerWidth, window.innerHeight]
  //vp_size = [256, 256]
  canvas.width = vp_size[0];
  canvas.height = vp_size[1];

  var fbsize = Math.max(vp_size[0], vp_size[1]);
  fbsize = 1 << 31 - Math.clz32(fbsize); // nearest power of 2

  blurFB = [];
  for ( var i = 0; i < 2; ++ i ) {
    fb = gl.createFramebuffer();
    fb.width = fbsize;
    fb.height = fbsize;
    gl.bindFramebuffer( gl.FRAMEBUFFER, fb );
    fb.color0_texture = gl.createTexture();
    gl.bindTexture( gl.TEXTURE_2D, fb.color0_texture );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST );
    gl.texImage2D( gl.TEXTURE_2D, 0, gl.RGBA, fb.width, fb.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null );
    fb.renderbuffer = gl.createRenderbuffer();
    gl.bindRenderbuffer( gl.RENDERBUFFER, fb.renderbuffer );
    gl.renderbufferStorage( gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, fb.width, fb.height );
    gl.framebufferTexture2D( gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, fb.color0_texture, 0 );
    gl.framebufferRenderbuffer( gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, fb.renderbuffer );
    gl.bindTexture( gl.TEXTURE_2D, null );
    gl.bindRenderbuffer( gl.RENDERBUFFER, null );
    gl.bindFramebuffer( gl.FRAMEBUFFER, null );
    blurFB.push( fb );
  }
}

function Fract( val ) { 
  return val - Math.trunc( val );
}
function CalcAng( deltaTime, intervall ) {
  return Fract( deltaTime / (1000*intervall) ) * 2.0 * Math.PI;
}
function CalcMove( deltaTime, intervall, range ) {
  var pos = self.Fract( deltaTime / (1000*intervall) ) * 2.0
  var pos = pos < 1.0 ? pos : (2.0-pos)
  return range[0] + (range[1] - range[0]) * pos;
}    
function EllipticalPosition( a, b, angRag ) {
  var a_b = a * a - b * b
  var ea = (a_b <= 0) ? 0 : Math.sqrt( a_b );
  var eb = (a_b >= 0) ? 0 : Math.sqrt( -a_b );
  return [ a * Math.sin( angRag ) - ea, b * Math.cos( angRag ) - eb, 0 ];
}

function IdentM44() {
  return [ 1, 0, 0, 0,    0, 1, 0, 0,    0, 0, 1, 0,    0, 0, 0, 1 ];
};

function RotateAxis(matA, angRad, axis) {
  var aMap = [ [1, 2], [2, 0], [0, 1] ];
  var a0 = aMap[axis][0], a1 = aMap[axis][1]; 
  var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);
  var matB = matA.slice(0);
  for ( var i = 0; i < 3; ++ i ) {
      matB[a0*4+i] = matA[a0*4+i] * cosAng + matA[a1*4+i] * sinAng;
      matB[a1*4+i] = matA[a0*4+i] * -sinAng + matA[a1*4+i] * cosAng;
  }
  return matB;
}

function Rotate(matA, angRad, axis) {
  var s = Math.sin(angRad), c = Math.cos(angRad);
  var x = axis[0], y = axis[1], z = axis[2]; 
  matB = [
      x*x*(1-c)+c,   x*y*(1-c)-z*s, x*z*(1-c)+y*s, 0,
      y*x*(1-c)+z*s, y*y*(1-c)+c,   y*z*(1-c)-x*s, 0,
      z*x*(1-c)-y*s, z*y*(1-c)+x*s, z*z*(1-c)+c,   0,
      0,             0,             0,             1 ];
  return Multiply(matA, matB);
}    

function Multiply(matA, matB) {
  matC = IdentM44();
  for (var i0=0; i0<4; ++i0 )
      for (var i1=0; i1<4; ++i1 )
          matC[i0*4+i1] = matB[i0*4+0] * matA[0*4+i1] + matB[i0*4+1] * matA[1*4+i1] + matB[i0*4+2] * matA[2*4+i1] + matB[i0*4+3] * matA[3*4+i1]  
  return matC;
}

function Cross( a, b ) { return [ a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0], 0.0 ]; }
function Dot( a, b ) { return a[0]*b[0] + a[1]*b[1] + a[2]*b[2]; }
function Normalize( v ) {
  var len = Math.sqrt( v[0] * v[0] + v[1] * v[1] + v[2] * v[2] );
  return [ v[0] / len, v[1] / len, v[2] / len ];
}

Camera = function( pos, target, up, fov_y, vp, near, far ) {
this.Time = function() { return Date.now(); }
this.pos = pos;
this.target = target;
this.up = up;
this.fov_y = fov_y;
this.vp = vp;
this.near = near;
this.far = far;
this.Perspective = function() {
    var n = this.near;
    var f = this.far;
    var fn = f + n;
    var f_n = f - n;
    var r = this.vp[0] / this.vp[1];
    var t = 1 / Math.tan( Math.PI * this.fov_y / 360 );
    return [
        t/r, 0, 0,          0,
        0,   t, 0,          0,
        0,   0, -fn/f_n,   -1,
        0,   0, -2*f*n/f_n, 0 ];
}; 
this.LookAt = function() {
    var mz = Normalize( [ this.pos[0]-this.target[0], this.pos[1]-this.target[1], this.pos[2]-this.target[2] ] );
    var mx = Normalize( Cross( this.up, mz ) );
    var my = Normalize( Cross( mz, mx ) );
    var tx = Dot( mx, this.pos );
    var ty = Dot( my, this.pos );
    var tz = Dot( [-mz[0], -mz[1], -mz[2]], this.pos ); 
    return [mx[0], my[0], mz[0], 0, mx[1], my[1], mz[1], 0, mx[2], my[2], mz[2], 0, tx, ty, tz, 1]; 
};
this.Update = function(vp_size) {
    if (vp_size)
        this.vp = vp_size;
};
}

var ShProg = {
Create: function (shaderList) {
  var shaderObjs = [];
  for (var i_sh = 0; i_sh < shaderList.length; ++i_sh) {
    var shderObj = this.Compile(shaderList[i_sh].source, shaderList[i_sh].stage);
    if (shderObj) shaderObjs.push(shderObj);
  }
  var prog = {}
  prog.progObj = this.Link(shaderObjs)
  if (prog.progObj) {
    prog.attrInx = {};
    var noOfAttributes = gl.getProgramParameter(prog.progObj, gl.ACTIVE_ATTRIBUTES);
    for (var i_n = 0; i_n < noOfAttributes; ++i_n) {
      var name = gl.getActiveAttrib(prog.progObj, i_n).name;
      prog.attrInx[name] = gl.getAttribLocation(prog.progObj, name);
    }
    prog.uniLoc = {};
    var noOfUniforms = gl.getProgramParameter(prog.progObj, gl.ACTIVE_UNIFORMS);
    for (var i_n = 0; i_n < noOfUniforms; ++i_n) {
      var name = gl.getActiveUniform(prog.progObj, i_n).name;
      prog.uniLoc[name] = gl.getUniformLocation(prog.progObj, name);
    }
  }
  return prog;
},
AttrI: function (prog, name) { return prog.attrInx[name]; },
UniformL: function (prog, name) { return prog.uniLoc[name]; },
Use: function (prog) { gl.useProgram(prog.progObj); },
SetI1: function (prog, name, val) { if (prog.uniLoc[name]) gl.uniform1i(prog.uniLoc[name], val); },
SetF1: function (prog, name, val) { if (prog.uniLoc[name]) gl.uniform1f(prog.uniLoc[name], val); },
SetF2: function (prog, name, arr) { if (prog.uniLoc[name]) gl.uniform2fv(prog.uniLoc[name], arr); },
SetF3: function (prog, name, arr) { if (prog.uniLoc[name]) gl.uniform3fv(prog.uniLoc[name], arr); },
SetF4: function (prog, name, arr) { if (prog.uniLoc[name]) gl.uniform4fv(prog.uniLoc[name], arr); },
SetM33: function (prog, name, mat) { if (prog.uniLoc[name]) gl.uniformMatrix3fv(prog.uniLoc[name], false, mat); },
SetM44: function (prog, name, mat) { if (prog.uniLoc[name]) gl.uniformMatrix4fv(prog.uniLoc[name], false, mat); },
Compile: function (source, shaderStage) {
  var shaderScript = document.getElementById(source);
  if (shaderScript)
    source = shaderScript.text;
  var shaderObj = gl.createShader(shaderStage);
  gl.shaderSource(shaderObj, source);
  gl.compileShader(shaderObj);
  var status = gl.getShaderParameter(shaderObj, gl.COMPILE_STATUS);
  if (!status) alert(gl.getShaderInfoLog(shaderObj));
  return status ? shaderObj : null;
},
Link: function (shaderObjs) {
  var prog = gl.createProgram();
  for (var i_sh = 0; i_sh < shaderObjs.length; ++i_sh)
    gl.attachShader(prog, shaderObjs[i_sh]);
  gl.linkProgram(prog);
  status = gl.getProgramParameter(prog, gl.LINK_STATUS);
  if ( !status ) alert(gl.getProgramInfoLog(prog));
  return status ? prog : null;
} };

var VertexBuffer = {
Create: function(attribs, indices, type) {
  var buffer = { buf: [], attr: [], inx: gl.createBuffer(), inxLen: indices.length, primitive_type: type ? type : gl.TRIANGLES };
  for (var i=0; i<attribs.length; ++i) {
    buffer.buf.push(gl.createBuffer());
    buffer.attr.push({ size : attribs[i].attrSize, loc : attribs[i].attrLoc, no_of: attribs[i].data.length/attribs[i].attrSize });
    gl.bindBuffer(gl.ARRAY_BUFFER, buffer.buf[i]);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array( attribs[i].data ), gl.STATIC_DRAW);
  }
  gl.bindBuffer(gl.ARRAY_BUFFER, null);
  if ( buffer.inxLen > 0 ) {
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buffer.inx);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( indices ), gl.STATIC_DRAW);
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, null);
  }
  return buffer;
},
Draw: function(bufObj) {
  for (var i=0; i<bufObj.buf.length; ++i) {
    gl.bindBuffer(gl.ARRAY_BUFFER, bufObj.buf[i]);
    gl.vertexAttribPointer(bufObj.attr[i].loc, bufObj.attr[i].size, gl.FLOAT, false, 0, 0);
    gl.enableVertexAttribArray( bufObj.attr[i].loc);
  }
  if ( bufObj.inxLen > 0 ) {
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, bufObj.inx);
    gl.drawElements(bufObj.primitive_type, bufObj.inxLen, gl.UNSIGNED_SHORT, 0);
    gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );
  }
  else
    gl.drawArrays(bufObj.primitive_type, 0, bufObj.attr[0].no_of );
  for (var i=0; i<bufObj.buf.length; ++i)
    gl.disableVertexAttribArray(bufObj.attr[i].loc);
  gl.bindBuffer( gl.ARRAY_BUFFER, null );
} };

initScene();

})();
html,body { margin: 0; overflow: hidden; }
#gui { position : absolute; top : 0; left : 0; }
<script id="draw-shader-vs" type="x-shader/x-vertex">
precision mediump float;

attribute vec3 inPos;
attribute vec3 inNV;
attribute vec3 inCol;

varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;

uniform mat4 u_projectionMat44;
uniform mat4 u_modelViewMat44;

void main()
{
    vertNV      = mat3( u_modelViewMat44 ) * normalize( inNV );
    vertCol     = inCol;
    vec4 pos    = u_modelViewMat44 * vec4( inPos, 1.0 );
    vertPos     = pos.xyz / pos.w;
    gl_Position = u_projectionMat44 * pos;
}
</script>

<script id="draw-shader-fs" type="x-shader/x-fragment">
precision mediump float;

varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;

uniform float u_shininess;

void main()
{
    vec3 color = vertCol;
    vec3  normalV  = normalize( vertNV );
    vec3  eyeV     = normalize( -vertPos );
    vec3  halfV    = normalize( eyeV + normalV );
    float NdotH    = max( 0.0, dot( normalV, halfV ) );
    float shineFac = ( u_shininess + 2.0 ) * pow( NdotH, u_shininess ) / ( 2.0 * 3.14159265 );
    gl_FragColor   = vec4( color.rgb * (0.2 + NdotH), 1.0 );
} 
</script>

<script id="post-shader-vs" type="x-shader/x-vertex">
precision mediump float;

attribute vec2 inPos;

varying   vec2 pos;

void main()
{
    pos = inPos;
    gl_Position = vec4( inPos, 0.0, 1.0 );
}
</script>

<script id="blur-shader-fs" type="x-shader/x-fragment">
precision mediump float;

varying vec2 pos;

uniform sampler2D u_texture;
uniform vec2      u_textureSize;
uniform float     u_sigma;
uniform float     u_radius;
uniform vec2      u_dir;

float CalcGauss( float x, float sigma )
{
    if ( sigma <= 0.0 )
        return 0.0;
  return exp( -(x*x) / (2.0 * sigma) ) / (2.0 * 3.14157 * sigma);
}

void main()
{
    vec2 texC     = pos.st * 0.5 + 0.5;
    vec4 texCol   = texture2D( u_texture, texC );
    vec4 gaussCol = vec4( texCol.rgb, 1.0 );
    vec2 step     = u_dir / u_textureSize;
    for ( int i = 1; i <= 32; ++ i )
    {
        float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );
        if ( weight < 1.0/255.0 )
            break;
        texCol    = texture2D( u_texture, texC + u_radius * step * float(i) );
        gaussCol += vec4( texCol.rgb * weight, weight );
        texCol    = texture2D( u_texture, texC - u_radius * step * float(i) );
        gaussCol += vec4( texCol.rgb * weight, weight );
    }
    gaussCol.rgb = clamp( gaussCol.rgb / gaussCol.w, 0.0, 1.0 );
    gl_FragColor = vec4( gaussCol.rgb, 1.0 );
}
</script>

<div>
<form id="gui" name="inputs">
<table>
<tr> <td> <font color= #CCF>radius</font> </td> 
        <td> <input type="range" id="radius" min="1" max="1000" value="200"/></td> </tr>
<tr> <td> <font color= #CCF>blur</font> </td> 
        <td> <input type="range" id="sigma" min="1" max="50" value="10"/></td> </tr>
</table>
</form>
</div>

<canvas id="canvas" style="border: none;"></canvas>

于 2017-07-21T12:46:49.863 回答
0

通常，您需要将要模糊的场景绘制为带有附加纹理的帧缓冲区对象 (FBO)。

  • 创建帧缓冲区
  • 创建一个空纹理（数据参数应为空）
  • 绑定帧缓冲区和纹理
  • 将纹理作为颜色附加到帧缓冲区

此时绘图的其余部分应与主缓冲区完全相同，但请确保设置正确的视口。此过程将使您绘制到纹理。

现在您的场景有了纹理，您需要执行与模糊图像相同的过程。

  • 绑定你的主缓冲区（通常索引为 0）
  • 绑定纹理
  • 使用模糊着色器将纹理绘制到主缓冲区

然后，您可以使用具有 2 个调用的水平和垂直模糊着色器来优化它，这些调用使用另一个 FBO...

所以我会尝试在您的应用程序中执行一些步骤：

  • 创建一个绘制并显示三角形的场景
  • 创建一个 FBO，绘制它并在主缓冲区上绘制 FBO 纹理
  • 创建一个通过纹理绘制并显示模糊图像的场景
  • 创建一个在其上绘制场景的 FBO，然后在主缓冲区上从 FBO 绘制模糊纹理

如果您发现自己在这些方面遇到了麻烦，您可能想问一个关于它的具体问题。

于 2017-06-27T12:01:39.400 回答