FBO 的反射纹理得到正确的图像

Question

我正在使用 A FBO 捕捉四边形表面上方的反射。前提是把相机移到水面下然后渲染场景到fbo，然后像这样恢复到原来的观看位置：

WaterFrameBuffer fbos;


Water test(fbos.getReflectionTexture(), fbos.getRefractionTexture());
render->addWater(&test);
while (!glfwWindowShouldClose(window))
{
    GLfloat currentFrame = (float)glfwGetTime();
    deltaTime = currentFrame - lastFrame;
    lastFrame = currentFrame;
    gameController->update(deltaTime);

    //reflection buffer
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    fbos.bindReflectionFrameBuffer();
    float distance = 2 * (gameController->getGameCamera()->GetCameraPosition().y - 0);
    gameController->getGameCamera()->GetCameraPosition().y -= distance;
    gameController->getGameCamera()->flipPitch();
    render->renderScene();
    gameController->getGameCamera()->GetCameraPosition().y += distance;
    gameController->getGameCamera()->flipPitch();
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);

    //refraction buffer
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    fbos.bindRefractionFrameBuffer();
    render->renderScene();
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);

    render->renderScene();
    render->renderWater();
    glfwSwapBuffers(window);
}

但是我得到的结果是：

折射图像正确，但反射图像不正确。这是自己的反射

这是我正在使用的片段着色器：

  #version 330 core
   in vec3 ourColor;
   in vec4 clipSpace;
   in vec2 texC;
    out vec4 color;

 // Texture samplers
   uniform sampler2D reflectTex;
   uniform sampler2D refractTex;
   //uniform sampler2D dudvTex;
void main()
{
   vec3 ndc = (clipSpace.xyz / clipSpace.w)/ 2.0 + 0.5;
   vec2 reflectTexCoords = vec2(ndc.x, -ndc.y);
   vec2 refractTexCoords = vec2(ndc.x, ndc.y);

   //vec2 distortion1 = texture(dudvTex, vec2(texC.x, texC.y)).rg*2.0 - 1.0;
   //reflectTexCoords += distortion1;
   //refractTexCoords += distortion1;

    vec4 reflect = texture(reflectTex, reflectTexCoords);
    vec4 refract = texture(reflectTex, refractTexCoords);
    color = reflect;//mix(reflect,refract,0.5);
}

顶点着色器：

  #version 330 core
  layout (location = 0) in vec3 position;
   layout (location = 1) in vec3 color;
  layout (location = 2) in vec2 texCoord;

   out vec3 ourColor;
   out vec4 clipSpace;
   out vec2 texC;
   uniform mat4 model;
   uniform mat4 view;
   uniform mat4 projection;
   const float tiling = 6.0;
   void main()
   {
       clipSpace = projection*view*model *vec4(position, 1.0f);
       gl_Position = clipSpace;
       ourColor = color;
       texC = texCoord;
    }

关于如何解决这个问题或获取反射图像的替代方法有什么想法吗？

Answer 1

我假设您已将 GL_TEXTURE_WRAP_S 和 GL_TEXTURE_WRAP_T 的纹理环绕参数设置为 GL_CLAMP_TO_EDGE。参见 glTexParameter。

这会导致任何纹理坐标都被限制在 [0+1/(2*texturSize), 1-1/(2*textureSize)] 范围内。

要解决您的问题，您必须使用纹理环绕参数 GL_REPEAT，或者您必须确保纹理坐标在 [0.0, 1.0] 范围内。

上图中的问题是纹理坐标(-ndc.y)的y分量取反，导致纹理坐标在[0.0,-1.0]范围内。将坐标移动到 [1.0, 0.0] 范围内并使用 1.0 - ndc.y 代替：

vec2 reflectTexCoords = vec2(ndc.x, 1.0 - ndc.y);

FBO 的反射纹理得到正确的图像

Reflection texture from FBO getting to correct image

c++

opengl

glfw