Hello,

In this sketch I want to move the pink line with the mouse along the green line. The mouse pointer must be on the blue part to allow the displacement.

The problem: if the mouse is moved too fast, the pink bar disappears.

What's wrong ?

Please note the lines are in a 3D scene.

1. /*
2.        HANDLE + CONSTRAINT MOVE
3.       
4. */
5. import processing.opengl.* ;
6. import codeanticode.glgraphics.*;
7. import javax.media.opengl.*;
8. import javax.media.opengl.glu.*;
9. import java.nio.*;
10. // VARIABLES
11. PVector[] handleOne = new PVector[2];
12. boolean locked = boolean(0) ; // test verrouillage souris sur point ?
13. boolean bover = boolean(0) ;
14. int movingPoint = 0 ;
15. // Colors
16. int bgColor = color(255, 255, 255); // background color
17. int handleColor = color(255, 128, 220);
18. int squareColor = color(255, 0, 0);
19. int ellipseColor = color(0, 255, 255);
20. void setup() {
21.   size (500, 500, OPENGL);
22.   background(bgColor);
23.   smooth();
24.   ellipseMode(CENTER);
25.   rectMode(CENTER);
26.  
27.   // Line definition
28.   handleOne[0] = new PVector(0, 250, 0);
29.   handleOne[1] = new PVector(100, 250, 0);
30.  
31.  
32. }
33. void draw() {
34.   stroke(handleColor);
35.   strokeWeight(2);
36.   translate(50, 50, 0);
37.   rotateZ(map(-90, 0, height, 0, PI));
38.   //ellipse(handleOne[0].x, handleOne[0].y, 0, 10);
39.   //Draws handle line
40.   beginShape(LINES);
41.   vertex(handleOne[0].x, handleOne[0].y, 0);
42.   vertex(handleOne[1].x, handleOne[1].y, 0);
43.   endShape();
44.   //Draw reference line
45.   stroke(0, 255, 0);
46.   beginShape(LINES);
47.   vertex(50, 0, 0);
48.   vertex(50, 500, 0);
49.   endShape();
50.   //Draw Ellipse
51.   stroke(ellipseColor);
52.   fill(ellipseColor);
53.   ellipse(handleOne[0].x, handleOne[0].y, 0, 10);
54.  
55.   //Tests whether mouse rolls over points and draws red squares
56.     strokeWeight(1);
57.     if (locked) {
58.       squareColor = color(255, 0, 0);
59.     } else {
60.       squareColor = color(128, 0, 0);
61.     }
62.     stroke(squareColor);
63.     fill(squareColor);
64.     if(dist(mouseX, mouseY, screenX(handleOne[0].x, handleOne[0].y, handleOne[0].z), screenY(handleOne[0].x, handleOne[0].y, handleOne[0].z)) <= 5) {
65.       movingPoint = 1;
66.       rect(handleOne[0].x, handleOne[0].y, 10, 10);
67.     } else {
68.       movingPoint = -1;
69.     }
70.     if (movingPoint != -1) {
71.       bover = true ;
72.     } else {
73.       bover = false;
74.     }
75.     //
76. }
77. */
78.    CURRENTLY UNUSED
79. void keyPressed() {
80.   if (key == CODED) {
81.     if (keyCode == UP) {
82.       print(handleOne[0]);
83.       handleOne[0].y = handleOne[0].y-5;
84.       handleOne[1].y = handleOne[1].y-5;
85.     }
86.     if (keyCode == DOWN) {
87.       print(handleOne[0]);
88.       handleOne[0].y = handleOne[0].y+5;
89.       handleOne[1].y = handleOne[1].y+5;
90.     }
91.   }
92. }
93. */ 
94. //********** Detects whether mouse button is pressed
95. void mousePressed() {
96.   if(bover) {
97.     locked = true;
98.   } else {
99.     locked = false;
100.   }
101. }
102. //********** Moves selected point while button held
103. void mouseDragged() {
104.   if(locked) {
105.     strokeWeight(1);
106.     stroke(255,0,0);
107.     fill(255,0,0);
108.         //handleOne[0].x = getMouse3D()[0] ;
109.         handleOne[0].y = getMouse3D()[1] ;
110.         //handleOne[0].z = getMouse3D()[2] ;
111.         //handleOne[1].x = getMouse3D()[0]+100 ;
112.         handleOne[1].y = getMouse3D()[1] ;
113.         //handleOne[1].z = getMouse3D()[2] ;
114.         // mouse (screen) to world conversion
115.     }
116. }
117. //********** Unlocks upon button release
118. void mouseReleased() {
119.   locked = false;
120.   bover = false;
121. }
122. //************* SCREEN TO WORLD FUNCTION - found on old Processing forum ********************
123. float[] getMouse3D()
124. {
125.   ((PGraphicsOpenGL)g).beginGL();
126.   int viewport[] = new int[4];
127.   double[] proj=new double[16];
128.   double[] model=new double[16];
129.   ((PGraphicsOpenGL)g).gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0);
130.   ((PGraphicsOpenGL)g).gl.glGetDoublev(GL.GL_PROJECTION_MATRIX,proj,0);
131.   ((PGraphicsOpenGL)g).gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX,model,0);
132.   FloatBuffer fb = ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder()).asFloatBuffer();
133.   ((PGraphicsOpenGL)g).gl.glReadPixels(mouseX, height-mouseY, 1, 1, GL.GL_DEPTH_COMPONENT, GL.GL_FLOAT, fb);
134.   fb.rewind();
135.   double[] mousePosArr=new double[4];
136.   ((PGraphicsOpenGL)g).glu.gluUnProject((double)mouseX,height-(double)mouseY,(double)fb.get(0),model,0,proj,0,viewport,0,mousePosArr,0);
137.   ((PGraphicsOpenGL)g).endGL();
138.   return new float[]{(float)mousePosArr[0],(float)mousePosArr[1],(float)mousePosArr[2]};
139. }