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Computer Graphics Experiment II Part.2 3D Boxman

Posted on Edited on In Disqus:

图形学实验二第二部分——智障的3D小人 demo以及相机相关请看上一篇博文——3D Touring 绘图基本函数 ------

首先要实现个画正方体和长方体的函数，正方体是直接画六个面，长方体则是更改了scale后的画正方体。 

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void drawCube(double xPos, double yPos, double zPos)
{
	glPushMatrix();
		glTranslated(xPos, yPos, zPos);
		glBegin(GL_POLYGON);
		glVertex3d(0.0f, 0.0f, 0.0f);  //顶面
		glVertex3d(0.0f, 0.0f, -1.0f);
		glVertex3d(-1.0f, 0.0f, -1.0f);
		glVertex3d(-1.0f, 0.0f, 0.0f);
		glVertex3d(0.0f, 0.0f, 0.0f);  //正面
		glVertex3d(-1.0f, 0.0f, 0.0f);
		glVertex3d(-1.0f, -1.0f, 0.0f);
		glVertex3d(0.0f, -1.0f, 0.0f);
		glVertex3d(0.0f, 0.0f, 0.0f);  //右面
		glVertex3d(0.0f, -1.0f, 0.0f);
		glVertex3d(0.0f, -1.0f, -1.0f);
		glVertex3d(0.0f, 0.0f, -1.0f);
		glVertex3d(-1.0f, 0.0f, 0.0f); //左面
		glVertex3d(-1.0f, 0.0f, -1.0f);
		glVertex3d(-1.0f, -1.0f, -1.0f);
		glVertex3d(-1.0f, -1.0f, 0.0f);
		glVertex3d(0.0f, -1.0f, 0.0f);  //底面
		glVertex3d(0.0f, -1.0f, -1.0f);
		glVertex3d(-1.0f, -1.0f, -1.0f);
		glVertex3d(-1.0f, -1.0f, 0.0f);
		glVertex3d(0.0f, 0.0f, -1.0f);  //背面
		glVertex3d(-1.0f, 0.0f, -1.0f);
		glVertex3d(-1.0f, -1.0f, -1.0f);
		glVertex3d(0.0f, -1.0f, -1.0f);
		glEnd();
	glPopMatrix();
}
void drawBox(double xPos, double yPos, double zPos, double xLen, double yLen, double zLen)
{
	glPushMatrix();
		glTranslated(xPos, yPos, zPos);
		glScaled(xLen, yLen, zLen); 
		drawCube(0, 0, 0);
	glPopMatrix();
}
然后画小人所需要用到的绘图函数基本就完成了。

小人的组成

本次试验中，先从简单的情况入手，我先将小人分成了身体、头、左臂、右臂、左腿、右腿五个部分，五个部分用树结构链接，其中身体是根节点，其他的均是其子节点。 

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Man() {
		body = Box(Vector3d(1,2,5), Vector3d(1, 2, 3), Vector3d(0,0,0));
		body.color = Vector3d(0, 0, 1); 
		int angArm = sin(time/100) * 30;
		int angLeg= sin(time/100) * 10;
		Box *head = new Box(Vector3d(0,-0.5,1),Vector3d(1,1,1));
		Box *lArm = new Box(Vector3d(0,0.8,0),Vector3d(0.8,0.8,2),
				Vector3d(0,1,0),
				Vector3d(-0.5,0,0),
				angArm);
		Box *rArm = new Box(Vector3d(0,-2,0),Vector3d(0.8,0.8,2),
				Vector3d(0,-1,0),
				Vector3d(-0.5,0,0),
				angArm);
		Box *lLeg = new Box(Vector3d(0,-0.1,-3),Vector3d(0.8,0.8,2),
				Vector3d(0,-1,0),
				Vector3d(-0.5,0,0),
				angLeg);
		Box *rLeg = new Box(Vector3d(0,-1.1,-3),Vector3d(0.8,0.8,2),
				Vector3d(0,1,0),
				Vector3d(-0.5,0,0),
				angLeg);
		body.addNxt(head);
		body.addNxt(lArm);
		body.addNxt(rArm);
		body.addNxt(lLeg);
		body.addNxt(rLeg);
	}
注意下这两句 
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int angArm = sin(time/100) * 30;
int angLeg= sin(time/100) * 10;
计算了胳膊和腿根据time的摆动（旋转）角度，需要注意的是，在后面调用时注意其正负号，避免出现顺拐的情况(x 其中，Box是一个封装起来的长方体，主要包括了一个长方体、颜色、旋转点、旋转轴、存储树结构的指针数组等。 
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class Box {
public:
	int len;
	double angle;
	Vector3d base, scale, rotN, color, rotP;
	Box* nxt[maxnxt];
	Box() { 
		angle = 0;
		len = 0;
		color = Vector3d(1, 1, 1);
		rotP = Vector3d(0, 0, 0);
	};
	Box(Vector3d base_, Vector3d scale_,
		Vector3d rotN_=Vector3d(0,0,0),
		Vector3d rotP_=Vector3d(0,0,0),
		double angle_=0,
		Vector3d color_ = Vector3d(1, 1, 1)) {
		angle = angle_;
		base = base_;
		scale = scale_;
		rotN = rotN_;
		len = 0;
		rotP = rotP_;
		color = color_;
	}
	void draw() {
		glPushMatrix();
			if (rotN.norm() != 0) {
				glTranslated(rotP.x(), rotP.y(), rotP.z());		//平移到旋转点
				glRotated(angle, rotN.x(), rotN.y(), rotN.z());	//旋转
				glTranslated(-rotP.x(), -rotP.y(), -rotP.z());	//平移回去
			}
			glColor3d(color.x(), color.y(), color.z());
			glTranslated(base.x(), base.y(), base.z());
			drawBox(Vector3d(0,0,0),scale);
			for (int i = 0; i < len; i++) {
				glPushMatrix();
				nxt[i]->draw();
				glPopMatrix();
			}
		glPopMatrix();
	}
	void addNxt(Box *x) {
		nxt[len] = x;
		len++;
	}
};
大部分的组成都介绍的差不多了，当然这个系统还是比较简单，调试时除了写相机系统时由于没有坐标系没有很方便的找出错误，另外深度测试时卡了一会儿之外剩下的还算蛮顺利，具体代码请移步github