渲染处理中的近多边形对象的剪辑

Question

我正在处理3D模型中的对象，并且存在一个问题，即当对象距离摄像机太近时，它们的渲染会被剪切（即，对象的最近位不会呈现）。这在P3D和OPENGL模式下都会发生。下右图说明：

不知道如何阻止这种情况发生？代码如下，可在线测试openprocessing.org。提前谢谢了。

void setup() { 
    size(600, 400, P3D); 
    stroke(0); 
    rectMode(CENTER); 
    fill(200); 

    // initialise camera variables 
    scaleY = PI/height; 
    scaleX = 2*PI/width; 
    camDir = PI/3; 
    camElev = PI/2; 
    MouseX = width/2; 
    MouseY = height/3; 
    turnCamera(); 
    camF_rel = setVector(camDir, camElev); 
} 

void draw() { 
    background(255); 

    // CAMERA & CONTROL OPERATIONS 
    MouseX = constrain(mouseX, 0, width); 
    MouseY = constrain(mouseY, 0, height); 
    setCamera(); 
    camera(camP.x, camP.y, camP.z, camF_abs.x, camF_abs.y, camF_abs.z, 0, 0, -1); 

    // DRAW ENVIRONMENT 
    // checkered plane 
    fill(150,200,255); 
    for (int i=-10; i<10; i++) { 
    for (int j=-10; j<10; j++) { 
     noStroke(); 
     if ((i+j)%2 == 0) rect(i*50, j*50, 50, 50); 
    } 
    } 
    // vertical line 
    noFill(); 
    stroke(100); 
    box(1000); 
} 


// camera position and focus variables 
PVector camP = new PVector(0, 1200, 700); // camera position 
PVector camF_abs = new PVector();  // camera focus (absolute position) 
PVector camF_rel = new PVector();  // camera focus (relative vector) 
float camDir, camElev;    // last camera bearing/elevation angles 
float mx, my;       // last mouse X/Y 
float MouseX, MouseY;     // replicate inbuilt mouse variables 
float scaleY;       // scale mouseY inputs to vertical movement 
float scaleX;       // scale mouseX inputs to horizontal movement 
int direction = 0;     // code for controling movement 
float moveSpeed = 10;     // overall controls responsiveness 


// main camera calculation operations 
void setCamera() { 
    camF_rel = setVector(camDir, camElev); 
    if (direction >= 1 & direction <= 4) moveCamera(moveSpeed); 
    if (direction >= 5 & direction <= 6) elevCamera(moveSpeed); 

    camF_abs = camF_rel.get(); 
    camF_abs.add(camP); 
} 


PVector setVector(float dir, float elev){ 
    //generic function to calculate the PVector based on radial coordinates 
    PVector v = new PVector(cos(dir), sin(dir), 0); 
    float fz = -sin(elev); 
    float fy = sqrt(1-pow(fz, 2)); 
    v.mult(fy); 
    v.z = fz; 
    return(v); 
} 


void moveCamera (float speed) { 
    PVector moveto = new PVector(); 

    // left/right movement 
    if (direction%2 == 0) { 
    float dir = 0; 
    if (direction == 2) dir = camDir + PI/2; // right 
    else    dir = camDir - PI/2; // left 
    PVector v = setVector(dir, 0); 
    v.mult(speed); 
    camP.add(v); 
    } 

    // forward/backward movement 
    else { 
    moveto = camF_rel.get(); 
    if (direction == 1) moveto.mult(-1); // forward 
    } 

    moveto.normalize(); 
    moveto.mult(speed); 
    camP.sub(moveto); 
} 


void turnCamera(){ 
    float x = MouseX - mx; 
    float x_scaled = x * scaleX; 
    float y = MouseY - my; 
    float y_scaled = y * scaleY; 
    camDir += x_scaled; 
    camElev += y_scaled; 
    mx = MouseX; 
    my = MouseY; 

} 


void elevCamera (float speed) { 
    if (direction == 5) { // lower camera 
    camP.z -= speed;    
    camF_abs.z -= speed; 
    } 
    else {     // raise camera 
    camP.z += speed;    
    camF_abs.z += speed; 
    } 
} 


void keyPressed() { 
    if  (keyCode == 38 | key == 'w') direction = 1; // move forward 
    else if (keyCode == 39 | key == 'd') direction = 2; // move right 
    else if (keyCode == 40 | key == 's') direction = 3; // move backward 
    else if (keyCode == 37 | key == 'a') direction = 4; // move left 
    else if (key == 'z')     direction = 5; // lower camera 
    else if (key == 'x')     direction = 6; // raise camera 
} 


void keyReleased() { 
    direction = 0; 
} 


void mouseMoved() { // turns the camera 
    turnCamera(); 
} 

Answer 1

您可以通过调用Processing中的perspective()函数来控制近距离和远距离的裁剪距离。

这些行添加到您的设置（）和问题消失了：

float fov = PI/3.0; 
float cameraZ = (height/2.0)/tan(fov/2.0); 
float nearClippingDistance = 0.01; // default is cameraZ/10.0 
perspective(fov, float(width)/float(height), nearClippingDistance, cameraZ*10.0); 

您可以通过将前几次后，这条线找到附近的草图剪辑距离默认：

println(cameraZ/10.0); // output: 34.6410