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- To move your object towards a location,provided targeted location and current location, you can suppose your current location origin and then get the relative position of the target location in polar coordinate.
- This will give you the direction you need to travel.
- Given the speed you want the object to travel,
Stepped example : (Click mouse to step, Hold down to see the hint, More content under demo 1, please scroll down)
Processing Height 600 Width 600 final int appwidth = 600; final int appheight = 600; final float stepsize = 10; targetedobject myobject; class targetedobject { // This is the object to move int mcurrentx, mcurrenty; // This will store the current location of the object int mtargetx, mtargety; // This will store the target location of the object int mtargetx_t, mtargety_t; // Step travel float mrotation; // This is the current orientation of this object float thisstep; boolean demostep; targetedobject( int x, int y, int r ) { // Initialize with coordinate and orientation mcurrentx = x; mtargetx = x; mcurrenty = y; mtargety = y; mrotation = r; demostep = false; } void updatedraw() { //Draws the shape pushMatrix(); translate( mcurrentx, mcurrenty ); rotate( mrotation ); noStroke(); fill( 255, 0, 0 ); ellipse(0, 0, 40, 40); noFill(); stroke(255); strokeWeight(5); line( -10, 0, 10, 0 ); line( 10, 0, 5, -5 ); line( 10, 0, 5, 5 ); popMatrix(); this.drawhelper(); } void drawhelper() { if ( this.demostep ) { //Need draw float textx, texty; noFill(); strokeWeight(3); stroke( 0, 255, 255, 192 ); line( this.mcurrentx, this.mcurrenty, this.mtargetx, this.mtargety ); line( this.mtargetx, this.mcurrenty, this.mtargetx, this.mtargety ); line( this.mcurrentx, this.mcurrenty, this.mtargetx, this.mcurrenty ); textSize(24); textAlign(CENTER, BOTTOM); noStroke(); fill(255); textx = (this.mtargetx + this.mcurrentx) / 2; texty = this.mcurrenty; text( "X2 - X1", textx, texty ); textAlign(LEFT, CENTER); textx = this.mtargetx; texty = (this.mtargety + this.mcurrenty) / 2; text( "Y2 - Y1", textx, texty ); textAlign(CENTER, CENTER); textx = (this.mtargetx + this.mcurrentx) / 2; texty = (this.mtargety + this.mcurrenty) / 2; text( "L", textx, texty ); } } void startstep(int x, int y) { float targetlength; float temprotation; this.demostep = true; this.mtargetx = x; this.mtargety = y; targetlength = sqrt( pow( this.mtargetx - this.mcurrentx, 2 ) + pow( this.mtargety - this.mcurrenty, 2 ) ); //Get the target distance if (targetlength <= 0.5) { this.mrotation = 0; return; //Do not move } if (targetlength > stepsize) { //Calculate step size this.thisstep = stepsize; } else { this.thisstep = targetlength; } temprotation = acos( (this.mtargetx - this.mcurrentx) / targetlength ); if ( this.mtargety > this.mcurrentxmcurrenty ) { //> 180 degrees this.mrotation = temprotation; }else{ this.mrotation = 2 * PI - temprotation; } // Calculate the step target this.mtargetx_t = (int)(this.thisstep * cos(this.mrotation)); this.mtargety_t = (int)(this.thisstep * sin(this.mrotation)); } void endstep() { this.demostep = false; this.mcurrentx += this.mtargetx_t; this.mcurrenty += this.mtargety_t; } } void setup() { size(appwidth, appheight); background(0); myobject = new targetedobject( width / 2, height / 2, 0 ); } void draw() { background(0); myobject.updatedraw(); } void mousePressed() { if (mouseButton == LEFT) { myobject.startstep(mouseX, mouseY); } } void mouseReleased() { if ( myobject.demostep ) { myobject.endstep(); } }Code Block theme Midnight language java title Key Note //Get the target distance targetlength = sqrt( pow( this.mtargetx - this.mcurrentx, 2 ) + pow( this.mtargety - this.mcurrenty, 2 ) ); //Arc cosin adjacent side //Get the target distancedivide by Hypotenuse //OR arc sin subtense divide by Hypotenuse //Not using tangent to avoid Divide by Zero temprotation = acos( (this.mtargetx - this.mcurrentx) / targetlength ); //In this case, we are using //Arc cosin diagcosin, so for the angle > 180 which means that //targety is under currend y if ( this.mtargety > this.mcurrentxmcurrenty ) { //> 180 degrees this.mrotation = temprotation; }else{ this.mrotation = 2 * PI - temprotation; }
//Now that we have the rotation, we recalculate the x and y we need to travel this.mtargetx_t = (int)(this.thisstep * cos(this.mrotation)); this.mtargety_t = (int)(this.thisstep * sin(this.mrotation)); //Finally, move the object this.mcurrentx += this.mtargetx_t; this.mcurrenty += this.mtargety_t;