Question

我最近学习了opengl es 2.0，现在我尝试在我自己生成的三角形上进行高斯模糊。我在网上有一些难以理解的例子，大多数都是在图像上应用模糊。我知道我必须使用帧缓冲，但我不知道如何在此处绘制三角形并应用模糊。是否有可能在C ++中看到一个具有良好解释的真实完整的代码？

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;
}

Blur Shader：

#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));
}

Answer 1

我认为您已经交换了pIdBlur和pId。

我＆＃39;将为您介绍2次通过的高斯模糊着色器。这是一种近似，其在第一遍中沿着X轴首先模糊并且在第二遍中沿着Y轴模糊。这样可以获得更好的模糊效果。模糊着色器使用normal (or Gaussian) distribution。对于2次传球，使用相同的着色器程序，2次传球的单独方向设置，存储在制服vec2 u_dir中。模糊效果的强度可以使用[0.0,1.0]范围内的均匀变量float u_sigma来改变。

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 );
}

链接程序后，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" );

必须创建一个包含四边形的顶点数组对象，后者将在整个视口上绘制，用于屏幕空间模糊传递：

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，其纹理附加到其颜色平面。在第一个场景中绘制了场景。该第一个模糊传递使用第二个。第二个模糊过程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传递所需的一切。

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);

和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);

第二步是第一步模糊传球。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，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。
注意，纹理不能作为源和目标位于同时，这会导致不确定的行为要将纹理绑定到着色器，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);

要应用模糊传递，必须绘制视口区域的四边形。

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

第二次和最后一次模糊传球，类似于第一次模糊传球。第一个模糊过程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);

另见以下问题的答案：

请参阅类似的WebGL示例：

＆＃13;

(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();

})();

＆＃13;

html,body { margin: 0; overflow: hidden; }
#gui { position : absolute; top : 0; left : 0; }

＆＃13;

<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>

＆＃13;

Answer 2

通常，您需要将要模糊的场景绘制到具有附加纹理的帧缓冲对象（FBO）。

创建帧缓冲区
创建空纹理（数据参数应为null）
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。此过程将使您绘制纹理。

现在你的场景有纹理，你需要采用与模糊图像相同的程序。

绑定主缓冲区（通常索引为0）
绑定纹理
使用模糊着色器

然后，您可以使用具有2个调用的水平和垂直模糊着色器对其进行优化，该调用使用另一个FBO ......

所以我会尝试在你的应用程序中做一些步骤：

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

如果您发现自己遇到任何问题，可能需要就此提出具体问题。

OpenGL es 2.0高斯模糊三角形

2 个答案: