Add Jon Leech's method to draw shpere

.gitignore

@@ -0,0 +1,3 @@
+.*
+*.o
+build/*

build/dust3d.pro

@@ -8,7 +8,11 @@ INCLUDEPATH += ../src
 
 SOURCES += main.cpp \
 	mainwindow.cpp \
-	glwidget.cpp
+	glwidget.cpp \
+  drawcommon.c \
+  drawsphere.c
 
 HEADERS += mainwindow.h \
-	glwidget.h
+	glwidget.h \
+  drawcommon.h \
+  drawsphere.h

src/drawcommon.c

@@ -0,0 +1,20 @@
+#include "drawcommon.h"
+#include <math.h>
+
+void normalize(point *p) {
+  double mag;
+  mag = p->x * p->x + p->y * p->y + p->z * p->z;
+  if (mag != 0.0) {
+    mag = 1.0 / sqrt(mag);
+    p->x *= mag;
+    p->y *= mag;
+    p->z *= mag;
+  }
+}
+
+void midpoint(point *a, point *b, point *mid) {
+  mid->x = (a->x + b->x) * 0.5;
+  mid->y = (a->y + b->y) * 0.5;
+  mid->z = (a->z + b->z) * 0.5;
+}
+

src/drawcommon.h

@@ -0,0 +1,31 @@
+#ifndef DRAW_COMMON_H
+#define DRAW_COMMON_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+  float x;
+  float y;
+  float z;
+} point;
+
+typedef struct {
+  point pt[3];
+} triangle;
+
+typedef struct {
+  int npoly;
+  triangle *poly;
+} object;
+
+void normalize(point *p);
+void midpoint(point *a, point *b, point *mid);
+void drawTriangle(triangle *poly);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/drawsphere.c

@@ -0,0 +1,106 @@
+#include "drawcommon.h"
+#include "drawsphere.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * This function modified from [Jon Leech's implementation of sphere](ftp://ftp.ee.lbl.gov/sphere.c)  
+ * Jeremy HU (huxingyi@msn.com) 2016/12/16
+*/
+
+#define XPLUS {  1,  0,  0 }  /*  X */
+#define XMIN  { -1,  0,  0 }  /* -X */
+#define YPLUS {  0,  1,  0 }  /*  Y */
+#define YMIN  {  0, -1,  0 }  /* -Y */
+#define ZPLUS {  0,  0,  1 }  /*  Z */
+#define ZMIN  {  0,  0, -1 }  /* -Z */
+
+static const triangle octahedron[] = {
+  {{XPLUS, ZPLUS, YPLUS}},
+  {{YPLUS, ZPLUS, XMIN}},
+  {{XMIN,  ZPLUS, YMIN}},
+  {{YMIN,  ZPLUS, XPLUS}},
+  {{XPLUS, YPLUS, ZMIN}},
+  {{YPLUS, XMIN,  ZMIN}},
+  {{XMIN,  YMIN,  ZMIN}},
+  {{YMIN,  XPLUS, ZMIN}},
+};
+
+static void subdivide(object *old, object *subdivided) {
+  int i;
+  for (i = 0; i < old->npoly; ++i) {
+    triangle *oldt = &old->poly[i];
+    triangle *newt = &subdivided->poly[i * 4];
+    point a, b, c;
+
+    midpoint(&oldt->pt[0], &oldt->pt[2], &a);
+    midpoint(&oldt->pt[0], &oldt->pt[1], &b);
+    midpoint(&oldt->pt[1], &oldt->pt[2], &c);
+
+    normalize(&a);
+    normalize(&b);
+    normalize(&c);
+
+    newt->pt[0] = oldt->pt[0];
+    newt->pt[1] = b;
+    newt->pt[2] = a;
+    newt++;
+
+    newt->pt[0] = b;
+    newt->pt[1] = oldt->pt[1];
+    newt->pt[2] = c;
+    newt++;
+
+    newt->pt[0] = a;
+    newt->pt[1] = b;
+    newt->pt[2] = c;
+    newt++;
+
+    newt->pt[0] = a;
+    newt->pt[1] = c;
+    newt->pt[2] = oldt->pt[2];
+  }
+}
+
+int drawSphere(int level) {
+  int lv, i;
+  object oldObj, newObj;
+
+  if (level < 1) {
+    fprintf(stderr, "%s:level max greater than 0.\n", __FUNCTION__);
+    return -1;
+  }
+
+  oldObj.npoly = sizeof(octahedron) / sizeof(octahedron[0]);
+  oldObj.poly = (triangle *)malloc(oldObj.npoly * sizeof(triangle));
+  if (!oldObj.poly) {
+    fprintf(stderr, "%s:insufficient memory.\n", __FUNCTION__);
+    return -1;
+  }
+  memcpy(oldObj.poly, octahedron, oldObj.npoly * sizeof(triangle));
+
+  for (lv = 0; lv < level; lv++) {
+    newObj.npoly = oldObj.npoly * 4;
+    newObj.poly = (triangle *)malloc(newObj.npoly * sizeof(triangle));
+    if (!newObj.poly) {
+      fprintf(stderr, "%s:insufficient memory(levelLoop:%d).\n", 
+        __FUNCTION__, lv);
+      free(oldObj.poly);
+      return -1;
+    }
+
+    subdivide(&oldObj, &newObj);
+
+    free(oldObj.poly);
+    oldObj = newObj;
+  }
+
+  for (i = 0; i < newObj.npoly; ++i) {
+    drawTriangle(&newObj.poly[i]);
+  }
+
+  free(newObj.poly);
+
+  return 0;
+}

src/drawsphere.h

@@ -0,0 +1,14 @@
+#ifndef DRAW_SPHERE_H
+#define DRAW_SPHERE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int drawSphere(int level);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/glwidget.cpp

@@ -1,25 +1,35 @@
 #include <QtGui>
 #include <QtOpenGL>
 #include <assert.h>
-
 #include "glwidget.h"
+#include "drawcommon.h"
+#include "drawsphere.h"
+
+void drawTriangle(triangle *poly) {
+  int i;
+  glBegin(GL_TRIANGLES);
+  for (i = 0; i < 3; ++i) {
+    point *pt = &poly->pt[i];
+    glNormal3f(pt->x, pt->y, pt->z);
+    glVertex3f(pt->x, pt->y, pt->z);
+  }
+  glEnd();
+}
 
 GLWidget::GLWidget(QWidget *parent)
-    : QGLWidget(QGLFormat(QGL::SampleBuffers), parent)
-{
+  : QGLWidget(QGLFormat(QGL::SampleBuffers), parent) {
 }
 
-GLWidget::~GLWidget()
-{
+GLWidget::~GLWidget() {
 }
 
-void GLWidget::initializeGL()
-{
+void GLWidget::initializeGL() {
   GLfloat mat_specular[] = {1.0, 1.0, 1.0, 1.0};
   GLfloat mat_shininess[] = {50.0};
   GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0};
   GLfloat light[] = {1.0, 0.2, 0.2};
   GLfloat lmodel_ambient[] = {0.1, 0.1, 0.1, 1.0};
+
   glClearColor(0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_SMOOTH);
 
@@ -36,86 +46,19 @@ void GLWidget::initializeGL()
   glEnable(GL_DEPTH_TEST);
 }
 
-void normalize(float v[3]) 
-{    
-    GLfloat d = sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]); 
-    if (d == 0.0) 
-    {  
-        return;
-    }
-    v[0] /= d; v[1] /= d; v[2] /= d; 
-}
-
-void drawtriangle(float *v1, float *v2, float *v3) 
-{ 
-   glBegin(GL_TRIANGLES); 
-      glNormal3fv(v1); glVertex3fv(v1);    
-      glNormal3fv(v2); glVertex3fv(v2);    
-      glNormal3fv(v3); glVertex3fv(v3);    
-   glEnd(); 
-}
-
-void subdivide(float *v1, float *v2, float *v3) 
-{
-    GLfloat v12[3], v23[3], v31[3];    
-    GLint i;
-
-    for (i = 0; i < 3; i++) 
-    { 
-        v12[i] = v1[i]+v2[i]; 
-        v23[i] = v2[i]+v3[i];     
-        v31[i] = v3[i]+v1[i];    
-    } 
-    normalize(v12);    
-    normalize(v23); 
-    normalize(v31); 
-    drawtriangle(v1, v12, v31);    
-    drawtriangle(v2, v23, v12);    
-    drawtriangle(v3, v31, v23);    
-    drawtriangle(v12, v23, v31); 
-}
-
-// An example come from http://www.glprogramming.com/red/chapter02.html#name8
-
-#define X .525731112119133606 
-#define Z .850650808352039932
-
-static GLfloat vdata[12][3] = {    
-    {-X, 0.0, Z}, {X, 0.0, Z}, {-X, 0.0, -Z}, {X, 0.0, -Z},    
-    {0.0, Z, X}, {0.0, Z, -X}, {0.0, -Z, X}, {0.0, -Z, -X},    
-    {Z, X, 0.0}, {-Z, X, 0.0}, {Z, -X, 0.0}, {-Z, -X, 0.0} 
-};
-static GLuint tindices[20][3] = { 
-    {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1},    
-    {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3},    
-    {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6}, 
-    {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11} 
-};
-
-void GLWidget::paintGL()
-{
-    GLint i;
+void GLWidget::paintGL() {
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-    for (i = 0; i < 20; i++) 
-    { 
-        subdivide(&vdata[tindices[i][0]][0],       
-                 &vdata[tindices[i][1]][0],       
-                 &vdata[tindices[i][2]][0]); 
-    }
+  drawSphere(3);
 }
 
-void GLWidget::resizeGL(int w, int h)
-{
+void GLWidget::resizeGL(int w, int h) {
   glViewport(0, 0, (GLsizei)w, (GLsizei)h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
-    if (w <= h)
-    {
+  if (w <= h) {
     glOrtho(-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w,
        1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
-    }
-    else
-    {
+  } else {
     glOrtho(-1.5*(GLfloat)w/(GLfloat)h,
        1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);
   }
@@ -123,10 +66,8 @@ void GLWidget::resizeGL(int w, int h)
   glLoadIdentity();
 }
 
-void GLWidget::mousePressEvent(QMouseEvent *event)
-{
+void GLWidget::mousePressEvent(QMouseEvent *event) {
 }
 
-void GLWidget::mouseMoveEvent(QMouseEvent *event)
-{
+void GLWidget::mouseMoveEvent(QMouseEvent *event) {
 }

src/main.cpp

@@ -1,10 +1,18 @@
 #include <QApplication>
+#include <stdio.h>
+#include <assert.h>
 #include "mainwindow.h"
 
 int main(int argc, char *argv[])
 {
   QApplication a(argc, argv);
  	MainWindow w;
+
+  assert(0 != freopen((a.applicationDirPath() + 
+    "/dust3d.log").toUtf8(), "w", stdout));
+  assert(0 != freopen((a.applicationDirPath() + 
+    "/dust3d_error.log").toUtf8(), "w", stderr));
+
   w.show();
 
   return a.exec();