我正在开发一个项目来显示和生成一棵生长的树。我在这个项目上使用C++和OpenGL。树长到一定数量的树枝,停下来,然后树叶落到地上。我决定使用Lidenmayer系统以图形方式描述这一点,因为它似乎是创建结构和定义树的每个元素的更简单的替代方法。到目前为止,我可以展示树干和天空的树干,但是我失去了如何真正让树木生长新的树枝。我认为可能做一个for循环来控制这个,但我不知道如何完成它。什么是解决这个问题的好方法?如何用我的代码控制我的L系统模式?
我的L-系统规则:
推导长度:10 公理:F 的F - > G [-F] [+ F] GF ģ - 旋转> GG
角= 15.0度(.2618弧度)
更新:这是我到目前为止。
#include <math.h>
#include <windows.h>
#include <GL/gl.h>
#include <glut.h>
int treeSeed = 0;
float branchAngle = .2618;
/*
Controls the growth of the tree. Factor
of growth is inverse to that of the ShrinkTree
method
*/
//void GrowTree()
//{
/*Tree grows in a direction depending
on the L-System rules */
//
// int i;
// for(i = 0; i <=10 ; i++)
// {
//
// //grow tree
//
// }
//}
/*
Tree shrinks in a direction depending
on the L-System rules. Factor of shrinkage is
inverse to that of the GrowTree method.*/
void ShrinkTree()
{
/*int j;
for (j = -; j <=10 ; j++)
{
}*/
}
//void treeAninmation()
//{
//
// glutPostRedisplay();
//}
/*
Draws a leaf on the branch.
If the seed axiom is at zero,
a new leaf is drawn. Otherwise,
the branch shrinks to accomodate
existing leaves.
*/
void DrawLeaf()
{
if(treeSeed==0)
{
glBegin(GL_QUADS);
glColor3f(0.0f,1.0f,0.0f);
glVertex2f(-0.05, -40.5);
glVertex2f(-0.05, -20.5);
glVertex2f(-0.02, -40.5);
glVertex2f(-0.02,-20.5);
glEnd();
}
/*else
{
GrowTree();
DrawTwig(treeSeed-1);
glPushMatrix();
glRotate(branchAngle,1.0f,0.0f,0.0f);
DrawLeaf(treeSeed-1);
glPopMatrix();
glPushMatrix();
glRotate(branchAngle,);
DrawLeaf(treeSeed-1);
glPopMatrix();
}*/
}
void DrawTwig()
{
/*
Draws trunk of tree
Represents base scenario of
recursion
*/
if(treeSeed==0)
{
glLineWidth(5.0);
glBegin(GL_LINE_STRIP);
glColor3f(0.60f,0.40f,0.12f);
glVertex2f(-0.10, -80.5);
glVertex2f(-0.10, -100.5);
glEnd();
}
/*else
{
ShrinkTree();
DrawTwig(treeSeed-1);
}*/
}
/* Draws the tree with leaves *
Uses recursion to draw tree structure
Relies on L-System formula in order
to produce a tree
*/
void DrawTree()
{
DrawTwig(treeSeed);
//DrawLeaf(treeSeed);
}
/* Draws the horizon, the sky, and the ground*/
void RenderScene(void)
{
// clears color buffer
glClear(GL_COLOR_BUFFER_BIT);
/*
//GLfloat y;
GLfloat fSizes[2]; // Store supported line width range
GLfloat size; // Store supported line width increments
*/
//The horizon lies in the xy plane
glBegin(GL_LINE_STRIP);
glColor3f(0.0f,0.0f,0.0f); //sets color of horizon to black
glVertex2f(-135.0,0.0);
glVertex2f(135.0,0.0);
glEnd();
//The sky lies in the xy plane
//Starts at horizon line,
//goes upwards to height edge of screen,
//and goes rightwards to width edge of screen.
glBegin(GL_QUADS);
glColor3f(0.0f,0.0f,1.0f);
glVertex2f(135.0, 0.0);
glVertex2f(-135.0, 0.0);
glVertex2f(-135.0, 100.0);
glVertex2f(135.0,100.0);
glEnd();
DrawTree();
glFlush();
}
void SetupRC(void)
{
glClearColor(1.0f,1.0f,1.0f,1.0f);
}
void ChangeSize(GLsizei w, GLsizei h)
{
GLfloat aspectRatio;
//prevents divison by zero
if(h ==0)
h = 1;
//set Viewport to window dimensions
glViewport(0,0,w,h);
// Reset coordinate system
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// Establish clipping volume (left, right,bottom,top,near,far
aspectRatio = (GLfloat)w/(GLfloat)h;
if (w <= h)
glOrtho (-100.0, 100.0, -100/aspectRatio, 100/aspectRatio,1.0,-1.0);
else
glOrtho (-100.0 * aspectRatio, 100.0 * aspectRatio, -100.0, 100.0, 1.0, -1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void main(int argc, char **argv)
{
glutInit(&argc, argv);
/* Testing basic display functions for now */
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(1000, 1000);
glutCreateWindow("falling leaves");
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
//glutIdleFunc(treeAnimation);
//glutDisplayFunc(DrawTree);
SetupRC();
glutMainLoop();
}
好的,我决定将GroworShrink方法分成两个独立的方法,名为Grow和Shrink。这是我更新的代码。
/* \t Controls the growth of the tree */ //void Grow() //{ \t /*Tree grows in a direction depending \t on the L-System rules */ \t \t int i; \t \t for(i = 0; i <=10 ; i++) \t \t { \t \t \t \t \t \t //grow tree \t \t } \t \t } void Shrink() { \t int j; \t for (j = -; j <=10 ; j++) \t { \t } }
– user230013 2009-12-11 23:58:27对不起,难以阅读的片段,但我不知道如何编辑我目前的问题。 – user230013 2009-12-11 23:59:47
如果不知道树如何表示,这是不可能回答的。 – 2009-12-13 10:32:03