为什么OpenGL+GLSL着色器不输出任何东西？

Question

总之，我的全屏着色器没有输出任何东西，

• 在环境传递中的每个片段输出相同的颜色，以确保它是输出的。（作品）
• 在定向光路中的每个片段输出相同的颜色。（仍然一无所获）
• 将屏幕分辨率用于XY顶点坐标，而不是归一化坐标；
  • 这适用于环境传递，因为我可以看到结果如预期的那样变化。
  • 方向光通过时没有变化，我得到的输出也是一样的。

  这是申请代码；

  glBindFramebuffer(GL_READ_FRAMEBUFFER, m_GeometryBuffer->m_Name);
  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
  glDrawBuffers(1,draw_buffers);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  
  m_AmbientShader->Begin();
      m_AmbientShader->SetUniformInt1("Diffuse",m_DiffuseTexture->m_TextureUnit);
      // Draw full screen quad
      glBegin(GL_QUADS);
          glMultiTexCoord2i(GL_TEXTURE0,0,0);
          glVertex2i(-1,-1);
          glMultiTexCoord2i(GL_TEXTURE0,1,0);
          glVertex2i(1,-1);
          glMultiTexCoord2i(GL_TEXTURE0,1,1);
          glVertex2i(1,1);
          glMultiTexCoord2i(GL_TEXTURE0,0,1);
          glVertex2i(-1,1);
      glEnd();
  m_AmbientShader->End();
  
  const DirectionalLight& dl = scene.GetDirectionalLight();
  
  glDrawBuffers(1, draw_buffers);
  m_DirectionalLightShader->Begin();
  m_DirectionalLightShader->SetUniformInt1("Diffuse",m_DiffuseTexture->m_TextureUnit);
  m_DirectionalLightShader->SetUniformInt1("Position",m_PositionTexture->m_TextureUnit);
  m_DirectionalLightShader->SetUniformInt1("Normal",m_NormalTexture->m_TextureUnit);
  m_DirectionalLightShader->SetUniformFloat3("LightDir",dl.GetDirection());
  m_DirectionalLightShader->SetUniformFloat3("LightAmb",dl.GetAmb());
  m_DirectionalLightShader->SetUniformFloat3("LightDiff",dl.GetDiff());
  m_DirectionalLightShader->SetUniformFloat3("LightSpec",dl.GetSpec());
  m_DirectionalLightShader->SetUniformFloat3("LightAtt",dl.GetAtt());
  m_DirectionalLightShader->SetUniformFloat1("LightIntensity",dl.GetIntensity());
      // Draw full screen quad
      glBegin(GL_QUADS);
          glMultiTexCoord2i(GL_TEXTURE0,0,0);
          glVertex2i(-1,-1);
          glMultiTexCoord2i(GL_TEXTURE0,1,0);
          glVertex2i(1,-1);
          glMultiTexCoord2i(GL_TEXTURE0,1,1);
          glVertex2i(1,1);
          glMultiTexCoord2i(GL_TEXTURE0,0,1);
          glVertex2i(-1,1);
      glEnd();
  m_DirectionalLightShader->End();
  

  请原谅，如果我的数学是错误的，我一直在乱搞着色器，试图得到任何类型的输出，但这里是着色器源文件；

  varying out vec2 ScreenPos;
  
  varying out vec3 VSLightDir;
  
  uniform vec3 LightDir;
  uniform vec3 LightAmb;
  uniform vec3 LightDiff;
  uniform vec3 LightSpec;
  uniform float LightIntensity;
  
  void main()
  {
      gl_Position = gl_Vertex;
      ScreenPos = gl_MultiTexCoord0.st;
      VSLightDir = normalize((gl_ModelViewMatrix * vec4(LightDir,0.0)).xyz);
  }
  

  // Gbuffer textures
  uniform sampler2D Diffuse;
  uniform sampler2D Position;
  uniform sampler2D Normal;
  
  in vec2 ScreenPos;
  uniform vec3 LightDir;
  uniform vec3 LightAmb;
  uniform vec3 LightDiff;
  uniform vec3 LightSpec;
  uniform float LightIntensity;
  
  in vec3 VSLightDir;
  out vec4 OutColour;
  
  void main()
  {
      // Sample from the GBuffer
      vec4 Diffuse = texture2D(Diffuse, ScreenPos);
      vec4 VSPos = texture2D(Position, ScreenPos);
      vec4 MRT2 = texture2D(Normal, ScreenPos);
      vec3 VSNormal = normalize(MRT2.xyz);
      float Shininess = MRT2.w;
  
      float LDotN = dot(VSNormal, VSLightDir);
  
      vec3 View = -normalize(VSPos.xyz);
  
      // Compute ambient contribution
      vec3 ambient = LightIntensity * LightAmb * Diffuse.xyz;
  
      // Compute diffuse contribution
      vec3 diffuse = LightIntensity * LightDiff * Diffuse.xyz * max(0.0, LDotN);
  
      // Compute specular contribution
      vec3 HalfWay = normalize(LightDir + View);
      vec3 specular = (LDotN <= 0.0)
                  ? vec3(0.0)
                  : LightIntensity * LightSpec * Diffuse.xyz * pow(max(0.0, dot(VSNormal,HalfWay)), Shininess);
  
      OutColour = vec4(ambient + diffuse + specular, Diffuse.a);
      //OutColour = vec4(0.0,0.0,1.0,1.0); //Debug line
  }
  

  varying out vec2 ScreenPos;
  
  void main()
  {
      gl_Position = gl_Vertex;
  
      // Used for the position to sample from GBuffer
      ScreenPos = gl_MultiTexCoord0.st;
  }
  

  // Gbuffer textures
  uniform sampler2D Diffuse;
  
  in vec2 ScreenPos;
  
  out vec4 OutColour;
  
  void main()
  {
      OutColour = texture2D(Diffuse, ScreenPos);
      //OutColour = vec4(0.0,0.0,1.0,1.0);
  }
  

Answer 1

你启用深度测试了吗？我看到你正在清除深度缓冲区，所以我怀疑可能，但你绘制的第二个纹理的深度与第一个纹理完全相同。gldepthfunc默认值为gl_less，这将导致第二次抽签完全被拒绝。

否则，您希望如何将这两个平局结合起来？应该有一些勾兑吗？