4-OpenGLES绘制螺旋点、线

public class MyActivity extends Activity {
	private MyRenderer render;
	private MyGLSurfaceView view;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		view = new MyGLSurfaceView(this);
		render = new MyRenderer();
		view.setRenderer(render);
		view.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);// 脏渲染,命令渲染
		setContentView(view);
	}

	class MyGLSurfaceView extends GLSurfaceView {
		public MyGLSurfaceView(Context context) {
			super(context);
		}

		public MyGLSurfaceView(Context context, AttributeSet attrs) {
			super(context, attrs);
		}
	}

	public class MyRenderer implements GLSurfaceView.Renderer {
		private float ratio;
		private float xrotate = 0f;// 围绕x轴旋转角度
		private float yrotate = 0f;// 围绕x轴旋转角度
		
		@Override
		public void onSurfaceCreated(GL10 gl, EGLConfig config) {
			// 清屏色
			gl.glClearColor(0f, 0f, 0f, 1f);
			// 启用顶点缓冲区数组
			gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
		}

		@Override
		public void onSurfaceChanged(GL10 gl, int width, int height) {
			// 设置视口
			gl.glViewport(0, 0, width, height);
			ratio = (float) width / (float) height;
			// 投影矩阵
			gl.glMatrixMode(GL10.GL_PROJECTION);
			// 加载单位矩阵
			gl.glLoadIdentity();
			// 设置平截头体
			gl.glFrustumf(-ratio, ratio, -1, 1, 3f, 7f);
		}

		@Override
		public void onDrawFrame(GL10 gl) {
			// 清除颜色缓冲区
			gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
			// 设置绘图颜色
			gl.glColor4f(1f, 0f, 0f, 1f);

			// 操作模型视图矩阵
			gl.glMatrixMode(GL10.GL_MODELVIEW);
			gl.glLoadIdentity();
			// 设置眼球的参数
			GLU.gluLookAt(gl, 0f, 0f, 5f, 0f, 0f, 0f, 0f, 1f, 0f);

			// 旋转角度
			gl.glRotatef(xrotate, 1, 0, 0);
			gl.glRotatef(yrotate, 0, 1, 0);

			// 计算点坐标
			float r = 0.5f;// 半径
			List<Float> coordsList = new ArrayList<Float>();
			float x = 0f, y = 0f, z = 1f;
			float zstep = 0.01f;
			for (float alpha = 0f; alpha < Math.PI * 6; alpha += (float) (Math.PI / 16)) {
				x = (float) (r * Math.cos(alpha));
				y = (float) (r * Math.sin(alpha));
				z = z - zstep;
				coordsList.add(x);
				coordsList.add(y);
				coordsList.add(z);
			}

			// 转换点成为缓冲区
			ByteBuffer ibb = ByteBuffer.allocateDirect(coordsList.size() * 4);
			ibb.order(ByteOrder.nativeOrder());
			FloatBuffer fbb = ibb.asFloatBuffer();
			for (float f : coordsList) {
				fbb.put(f);
			}
			ibb.position(0);

			// 指定顶点指针
			gl.glVertexPointer(3, GL10.GL_FLOAT, 0, ibb);
			gl.glDrawArrays(GL10.GL_POINTS, 0, coordsList.size() / 3);// 3个坐标表示一个点
		}
	}

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		float step = 5f;
		// 逆时针旋转是正值,顺时针旋转是负值
		if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
			render.xrotate -= step;
		} else if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
			render.xrotate += step;
		} else if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
			render.yrotate += step;
		} else if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
			render.yrotate -= step;
		}
		// 请求渲染,和脏渲染配合使用
		view.requestRender();
		return super.onKeyDown(keyCode, event);
	}
}

螺旋线：gl.glDrawArrays(GL10.GL_POINTS,...)->gl.glDrawArrays(GL10.GL_LINE_STRIP,......)：

图元:
1.点
    pionts:
2.线
    lines:线段集合
    line_strip,线带
    line_loop,线环
3.三角形

本文地址：https://blog.csdn.net/itzyjr/article/details/107303440