Fix ball selection.

README.md

@@ -65,13 +65,15 @@ I follow the B-Mesh paper, made another test module inside Blender, and created
 <img src="screenshot/dust3d_subdivide_catmull_clark.png" width="124" height="128">  <img src="screenshot/dust3d_bmesh_subdivide_2.png" width="124" height="128">    
 There is a implementation of Catmull-Clark Subdivision algorithm on [rosettacode](https://rosettacode.org/wiki/Catmull%E2%80%93Clark_subdivision_surface/C), the code is very simple and beautiful, just lack of some memory alloc fail check. I translated the algorithm to use my own array implementation.  
 Now, the render result looks not bad after 2 times of subdivisions. I would like to mark this todo as done, though there are more polish steps on the original paper, I just leave it as to be done in the future.
-- [ ] Export Wavefront .obj  
 - [x] Render B-Mesh result  
 This todo already done in the B-Mesh algorithm implementation.  
-- [ ] Design UI for monster parts configuration  
-- [ ] Test B-Mesh realtime generation with UI  
+- [ ] Design UI for monster parts configuration (Jan 17, 2017 ~ Jan 18, 2017)  
+  *Skeleton Editor*  
+  There is good tutorial introduced how to implement object selection by mouse in OpenGL, written by [Bartek](http://www.bfilipek.com/2012/06/select-mouse-opengl.html).  
+  But there is a big pain in the progress of implement the object selection logic, because of resizeGL, the width and height which passed in as parameters of this function is not equal to the size of the window.
 - [ ] Render rigid animation  
 - [ ] png exporter for isometric 2.5D game  
-- [ ] Version 0.01 release  
+- [ ] Export Wavefront .obj
 - [ ] Materials merge of different parts      
+- [ ] Version 0.01 release  
 - [ ] Implement [the Skeleton of a Closed 3D Shape](http://www1.idc.ac.il/icgf/GraphicsSeminar2006/DCGskeleton06.pdf)  

src/render.cpp

@@ -28,20 +28,42 @@ int drawDebugPrintf(const char *fmt, ...) {
   va_start(args, fmt);
   vsnprintf(text, sizeof(text), fmt, args);
   debugOutputTop += 9;
-  if (debugOutputTop > 200) {
+  if (debugOutputTop > 400) {
     debugOutputTop = 0;
   }
+  glColor3f(0, 0, 0);
   return drawText(x, y, text);
 }
 
 static int drawBmeshBall(bmesh *bm, bmeshBall *ball) {
   float color[4];
   memcpy(color, bmeshBallColors[ball->type], sizeof(color));
-  vec3 mousePos[] = {{_this->mouseWorldX, _this->mouseWorldY,
-    _this->mouseWorldZ}};
-  if (vec3Distance(&ball->position, mousePos) <= ball->radius * 5) {
+  if (BMESH_BALL_TYPE_ROOT == ball->type || BMESH_BALL_TYPE_KEY == ball->type) {
+    vec3 a = {_this->mouseWorldNearX, _this->mouseWorldNearY,
+      _this->mouseWorldNearZ};
+    vec3 b = {_this->mouseWorldFarX, _this->mouseWorldFarY,
+      _this->mouseWorldFarZ};
+    vec3 ab, ap, q;
+    float abDotAb;
+    float apDotAb;
+    float t;
+    vec3Sub(&b, &a, &ab);
+    vec3Sub(&ball->position, &a, &ap);
+    abDotAb = vec3DotProduct(&ab, &ab);
+    apDotAb = vec3DotProduct(&ap, &ab);
+    t = apDotAb / abDotAb;
+    if (t < 0.0f) {
+      t = 0.0f;
+    } else if (t > 1.0f) {
+      t = 1.0f;
+    }
+    vec3Scale(&ab, t, &q);
+    vec3Add(&a, &q, &q);
+    //drawDebugPrintf("q: %f,%f,%f t:%f", q.x, q.y, q.z, t);
+    if (vec3Distance(&ball->position, &q) <= ball->radius) {
       color[3] = 1;
     }
+  }
   glColor4fv(color);
   drawSphere(&ball->position, ball->radius, 36, 24);
   return 0;
@@ -176,6 +198,12 @@ Render::Render(QWidget *parent)
   cameraAngleX = 30;
   cameraAngleY = -312;
   cameraDistance = 14.4;
+  //cameraAngleX = 0;
+  //cameraAngleY = 0;
+  //cameraDistance = 0;
+  
+  mouseScaleX = 1;
+  mouseScaleY = 1;
 }
 
 Render::~Render(void) {
@@ -221,7 +249,8 @@ void Render::initializeGL() {
 }
 
 void screenCoordsToWorld(float winX, float winY,
-    float *worldX, float *worldY, float *worldZ){
+    float *worldNearX, float *worldNearY, float *worldNearZ,
+    float *worldFarX, float *worldFarY, float *worldFarZ){
   GLint viewport[4];
   GLdouble modelview[16];
   GLdouble projection[16];
@@ -234,15 +263,46 @@ void screenCoordsToWorld(float winX, float winY,
 
   winX = (float)winX;
   winY = (float)viewport[3] - (float)winY;
-  winZ = 0;
   
+  winZ = 0;
   gluUnProject((GLdouble)winX, (GLdouble)winY, (GLdouble)winZ,
     (const GLdouble *)modelview, (const GLdouble *)projection, viewport,
     &x, &y, &z);
+  *worldNearX = (float)x;
+  *worldNearY = (float)y;
+  *worldNearZ = (float)z;
+  {
+    vec3 origin = {(float)x, (float)y, (float)z};
+    drawDebugPoint(&origin, 0);
+  }
   
-  *worldX = (float)x;
-  *worldY = (float)y;
-  *worldZ = (float)z;
+  winZ = 1;
+  gluUnProject((GLdouble)winX, (GLdouble)winY, (GLdouble)winZ,
+    (const GLdouble *)modelview, (const GLdouble *)projection, viewport,
+    &x, &y, &z);
+  *worldFarX = (float)x;
+  *worldFarY = (float)y;
+  *worldFarZ = (float)z;
+  {
+    vec3 origin = {(float)x, (float)y, (float)z};
+    drawDebugPoint(&origin, 1);
+  }
+  
+  {
+    vec3 topOrigin = {*worldNearX, *worldNearY, *worldNearZ};
+    vec3 bottomOrigin = {*worldFarX, *worldFarY, *worldFarZ};
+    glDisable(GL_LIGHTING);
+
+    // x z plane
+    glBegin(GL_LINES);
+      glColor3f(0.0, 0.0, 0.0);
+      glVertex3f(topOrigin.x, topOrigin.y, topOrigin.z);
+      glVertex3f(bottomOrigin.x, bottomOrigin.y, bottomOrigin.z);
+    glEnd();
+
+    glEnable(GL_LIGHTING);
+    //drawCylinder(&topOrigin, &bottomOrigin, 0.1, 36, 24);
+  }
 }
 
 #include "../data/bmesh_test_2.h"
@@ -265,16 +325,18 @@ void Render::paintGL() {
   drawDebugPrintf("cameraAngleX:%f cameraAngleY:%f cameraDistance:%f",
     cameraAngleX, cameraAngleY, cameraDistance);
   
+  screenCoordsToWorld(_this->mouseX, _this->mouseY,
+    &_this->mouseWorldNearX, &_this->mouseWorldNearY, &_this->mouseWorldNearZ,
+    &_this->mouseWorldFarX, &_this->mouseWorldFarY, &_this->mouseWorldFarZ);
+  glColor3f(0.0f, 0.0f, 0.0f);
+  drawDebugPrintf("%d,%d -> %f,%f,%f %f,%f,%f", _this->mouseX, _this->mouseY,
+    _this->mouseWorldNearX, _this->mouseWorldNearY, _this->mouseWorldNearZ,
+    _this->mouseWorldFarX, _this->mouseWorldFarY, _this->mouseWorldFarZ);
+
   drawGrid(10, 1);
 
   glEnable(GL_LIGHTING);
 
-  screenCoordsToWorld(_this->mouseX, _this->mouseY,
-    &_this->mouseWorldX, &_this->mouseWorldY, &_this->mouseWorldZ);
-  glColor3f(0.0f, 0.0f, 0.0f);
-  drawDebugPrintf("%d,%d -> %f,%f,%f", _this->mouseX, _this->mouseY,
-    _this->mouseWorldX, _this->mouseWorldY, _this->mouseWorldZ);
-
   if (0 == bm) {
     bmeshBall ball;
     bmeshBone bone;
@@ -363,6 +425,9 @@ void Render::paintGL() {
 }
 
 void Render::resizeGL(int w, int h) {
+  mouseScaleX = w / width();
+  mouseScaleY = h / height();
+  
   glViewport(0, 0, (GLsizei)w, (GLsizei)h);
 
   glMatrixMode(GL_PROJECTION);
@@ -385,16 +450,18 @@ void drawTestUnproject(void) {
 }*/
 
 void Render::mousePressEvent(QMouseEvent *event) {
-  mouseX = event->x();
-  mouseY = event->y();
+  mouseX = event->x() * mouseScaleX;
+  mouseY = event->y() * mouseScaleY;
 }
 
 void Render::mouseMoveEvent(QMouseEvent *event) {
-  cameraAngleY += (event->x() - mouseX);
-  cameraAngleX += (event->y() - mouseY);
+  int x = event->x() * mouseScaleX;
+  int y = event->y() * mouseScaleY;
+  cameraAngleY += (x - mouseX);
+  cameraAngleX += (y - mouseY);
   update();
-  mouseX = event->x();
-  mouseY = event->y();
+  mouseX = x;
+  mouseY = y;
 }
 
 void Render::wheelEvent(QWheelEvent * event) {

src/render.h

@@ -21,9 +21,14 @@ protected:
 public:
   int mouseX;
   int mouseY;
-  float mouseWorldX;
-  float mouseWorldY;
-  float mouseWorldZ;
+  float mouseScaleX;
+  float mouseScaleY;
+  float mouseWorldNearX;
+  float mouseWorldNearY;
+  float mouseWorldNearZ;
+  float mouseWorldFarX;
+  float mouseWorldFarY;
+  float mouseWorldFarZ;
   float cameraAngleX;
   float cameraAngleY;
   float cameraDistance;