OpenGL-GLLS單虛擬燈

Question

我的着色器有一個小問題。

頂點

varying vec3 normal, lightDir, eyeVec, spotDir;                              
varying mat4 viewMat;                                                         
uniform vec4 posluce; \\this is light position                                                         
uniform mat4 matrix;                                                          
uniform vec3 spotdir;                                                         
void main(){                                                                  
        viewMat = inverse(matrix);                                            
        vec3 posLuceWorld = (posluce*viewMat).xyz;                            
        spotDir = normalize(vec3(vec4(spotdir,0)*viewMat));                   
    normal = gl_NormalMatrix * gl_Normal;                                 
    vec3 vVertex = vec3(gl_ModelViewMatrix * gl_Vertex);                  
    lightDir = normalize(posLuceWorld.xyz - (gl_Vertex * viewMat).xyz);   
    eyeVec = normalize(-vVertex);                                         
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;               
}

分段

varying vec3 normal, lightDir, eyeVec,spotDir;                                         
varying mat4 viewMat;                                                                  
const float cos_outer_cone_angle = 0.8; // 36 degrees                                  
void main (void){                                                                      
vec4 amb =  vec4(0.1, 0.1, 0.1, 1.0);                                                  
vec4 diff = vec4(0.52, 0.81, 0.98, 1.0);                                               
vec4 spec = vec4(0.52, 0.81, 0.98, 1.0);                                               
float exp = 2.5f;                                                                      
float cutoff = 25.0f;                                                                  
float cosCut = cos(cutoff);                                                            

    vec4 final_color =                                                             
    (gl_FrontLightModelProduct.sceneColor * gl_FrontMaterial.ambient) +            
    (amb * gl_FrontMaterial.ambient);                                              

    vec3 L = lightDir;                                                             
    vec3 D = spotDir;                                                              

    float cos_cur_angle = dot(-L, D);                                               

    float cos_inner_cone_angle = cosCut;                                            

    float cos_inner_minus_outer_angle =                                             
          cos_inner_cone_angle - cos_outer_cone_angle;                              

    float spot = 0.0;                                                               
    spot = clamp((cos_cur_angle - cos_outer_cone_angle) /                           
           cos_inner_minus_outer_angle, 0.0, 1.0);                                  
    vec3 N = normalize(normal);                                                     
    float lambertTerm = max( dot(N,L), 0.0);                                        
    if(lambertTerm > 0.0){                                                          
        final_color += diff *                                                   
            exp *                                                           
            gl_FrontMaterial.diffuse *                                      
            lambertTerm * spot;                                             

        vec3 E = eyeVec;                                                        
        vec3 R = reflect(-L, N);                                                
        float specular = pow( max(dot(R, E), 0.0),                              
            gl_FrontMaterial.shininess );                                   
        final_color += spec *                                                   
            gl_FrontMaterial.specular *                                     
            specular * spot;                                                
    }                                                                               
    gl_FragColor = final_color;                                                     
}

我的顯示功能：

  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glEnable(GL_DEPTH_TEST);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  //Setting camera using orthonormal frame manipulation
      Matrix4x4 m;
      //Change view with mouse
      buildRotationMatrix(camera.frame.Yaxis, deg2rad(-yrot),  m);
      transform(m, camera.frame.Xaxis);
      transform(m, camera.frame.Yaxis);
      transform(m, camera.frame.Zaxis);
      //i traslate myself with the Keyborad
      if (up_key){
      camera.position.x += -camera.frame.Zaxis.x * speed;
      camera.position.y += -camera.frame.Zaxis.y * speed;
      camera.position.z += -camera.frame.Zaxis.z * speed;
    }
      if (down_key){
      camera.position.x += camera.frame.Zaxis.x * speed;
      camera.position.y += camera.frame.Zaxis.y * speed;
      camera.position.z += camera.frame.Zaxis.z * speed;
    }
      if (left_key){
      camera.position.x += -camera.frame.Xaxis.x * speed;
      camera.position.y += -camera.frame.Xaxis.y * speed;
      camera.position.z += -camera.frame.Xaxis.z * speed;
    }
      if (right_key){
      camera.position.x += camera.frame.Xaxis.x * speed;
      camera.position.y += camera.frame.Xaxis.y * speed;
      camera.position.z += camera.frame.Xaxis.z * speed;
      }

  pitch-=xrot*0.5; // change view speed
  if (pitch>90) pitch=90;
  if (pitch<-90) pitch=-90;

  Camera temp(camera);
  Matrix4x4 m2;
  buildRotationMatrix(temp.frame.Xaxis, deg2rad(pitch),  m2);
  transform(m2, temp.frame.Xaxis);
  transform(m2, temp.frame.Yaxis);
  transform(m2, temp.frame.Zaxis);

  Matrix4x4 c;
  buildCameraMatrix(temp,c);
  glMultMatrixf(c.GL_array());

    if(mouse_moved){
    mouse_moved=false;// this force my mouse in center 
    glutWarpPointer(width/2, height/2);
      }

      xrot=yrot=0;

      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      GLdouble ratio = static_cast<GLdouble>(width) / static_cast<GLdouble>(height);
      gluPerspective(45, //angolo di visuale
             ratio, //aspect ratio (rapporto tra larghezza e altezza)
             1, //Z near cutting plane
             1000); //Z far cutting plane

      glMatrixMode(GL_MODELVIEW);

      glUseProgram(ShaderProgram);

      GLint matrixR = glGetUniformLocation(ShaderProgram, "matrix");
      glUniformMatrix4fv(matrixR, 1, GL_FALSE, c.GL_array());

      GLint spot = glGetUniformLocation(ShaderProgram, "spotdir");
      float spotdirr[3] = {0.0, -1.0, 1.0};
      glUniform3fv(spot,1,spotdirr);

      GLint pos = glGetUniformLocation(ShaderProgram, "posluce");
      float light0_position[4] = {-0.17252*scale, 0.73089*scale, -0.52868*scale, 1};
      glUniform4fv(pos,1,light0_position);

      glPushMatrix();
        creaPavimento(); \\this create my floor
      glPopMatrix();

      glPushMatrix();
        GLfloat front_mat_diffuse[] = {0.25, 0.4, 0.98, 1.0};
        GLfloat front_mat_spec[] = {0.4, 0.4, 0.4, 1.0};
        GLfloat front_mat_ambi[] = {0.25, 0.25, 0.25, 1.0};
    glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, front_mat_diffuse);
    glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, front_mat_spec);
    glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, front_mat_ambi);
        GLfloat mShininess[] = {2};
        glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, mShininess);
        glTranslatef(0.0,1.0,6.0);
        glutSolidSphere(0.5, 20, 20);
      glPopMatrix();

      glFlush();
      glutSwapBuffers();

當我使用此着色器時，產生的光線不會照亮我的地板，而只會照亮一個球體，這是我的問題：為什么？ 怎么了？ 如果我使用OPENGL標准燈，效果很好。

我無法發布圖片。 對不起，我英語不好。

編輯：

我已經更改了一點着色器。 現在對地板和球體都適用，但是對於球體來說，地板截斷是完全錯誤的，但是方向卻是錯誤的。

頂點：

varying vec3 normal, lightDir, eyeVec, spotDirection;                         
varying mat4 viewMat;                                                         
uniform vec4 posluce;                                                         
uniform mat4 matrix;                                                          
uniform vec3 spotdir;                                                         
void main(){                                                                  
        viewMat = inverse(matrix);                                            
        spotDirection = normalize(vec3(vec4(spotdir,0.0)*viewMat));           
        vec3 lightPosition  = (posluce * viewMat).xyz;                        
    normal = gl_NormalMatrix * gl_Normal;                                 
    vec3 vVertex = vec3(gl_ModelViewMatrix * gl_Vertex);                  
    lightDir = normalize( (gl_Vertex * viewMat).xyz + lightPosition);     
    eyeVec = -vVertex;                                                    
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;               
}

這是新片段：

varying vec3 normal, lightDir, eyeVec,spotDirection;                                    
varying mat4 viewMat;                                                                   
const float cos_outer_cone_angle = 0.8; // 36 degrees                                   
void main (void){                                                                       
vec4 amb =  vec4(0.1, 0.1, 0.1, 1.0);                                                   
vec4 diff = vec4(0.52, 0.81, 0.98, 1.0);                                                
vec4 spec = vec4(0.52, 0.81, 0.98, 1.0);                                                
float exp = 2.5f;                                                                       
float cutoff = 25.0f;                                                                   
float cosCut = cos(cutoff);                                                             

    vec4 final_color =                                                              
    (gl_FrontLightModelProduct.sceneColor * gl_FrontMaterial.ambient) +             
    (amb * gl_FrontMaterial.ambient);                                               

    vec3 L = normalize(lightDir);                                                   
    vec3 D = normalize(spotDirection);                                              

    float cos_cur_angle = dot(-L, D);                                               

    float cos_inner_cone_angle = cosCut;                                            

    float cos_inner_minus_outer_angle =                                             
          cos_inner_cone_angle - cos_outer_cone_angle;                              

    float spot = 0.0;                                                               
    spot = clamp((cos_cur_angle - cos_outer_cone_angle) /                           
           cos_inner_minus_outer_angle, 0.0, 1.0);                                  
    vec3 N = normalize(normal);                                                     
    float lambertTerm = max( dot(N,L), 0.0);                                        
    if(lambertTerm > 0.0){                                                          
        final_color += diff *                                                   
            exp *                                                           
            gl_FrontMaterial.diffuse *                                      
            lambertTerm * spot;                                             

        vec3 E = normalize(eyeVec);                                             
        vec3 R = reflect(-L, N);                                                
        float specular = pow( max(dot(R, E), 0.0),                              
            gl_FrontMaterial.shininess );                                   
        final_color += spec *                                                   
            gl_FrontMaterial.specular *                                     
            specular * spot;                                                
    }                                                                               
    gl_FragColor = final_color;                                                     
}

Answer 1

如果我正確理解您的代碼和注釋，則球體，光源和照相機位於立方體內部。 這意味着立方體的法線朝外（您正在看其背面），因此點積dot(N,L)為負，這使lambert_term等於0 。 這進而導致整個照明計算被跳過。

您有兩個選擇。 修改着色器以照亮背面和正面，或者使用正確面對法線的方式渲染立方體。