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http://ios.9tech.cn/news/2013/1108/38495.html
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EAGLContext *context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];self.context = context; [EAGLContext setCurrentContext:context]; glGenFramebuffersOES(1, &_framebuffer); // 创建帧缓冲区glGenRenderbuffersOES(1, &_renderbuffer); // 创建绘制缓冲区glBindFramebufferOES(GL_FRAMEBUFFER_OES, _framebuffer); // 绑定帧缓冲区到渲染管线glBindRenderbufferOES(GL_RENDERBUFFER_OES, _renderbuffer); // 绑定绘制缓冲区到渲染管线glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, _renderbuffer); // 绑定绘制缓冲区到帧缓冲区 GLint width;GLint height;[context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:layer]; // 为绘制缓冲区分配存储区，此处将CAEAGLLayer的绘制存储区作为绘制缓冲区的存储区glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &width); // 获取绘制缓冲区的像素宽度glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &height); // 获取绘制缓冲区的像素高度 glGenRenderbuffersOES(1, &_depthbuffer); // 创建深度缓冲区glBindRenderbufferOES(GL_RENDERBUFFER_OES, _depthbuffer); // 绑定深度缓冲区到渲染管线glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, width, height); // 为深度缓冲区分配存储区glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES, GL_RENDERBUFFER_OES, _depthbuffer); // 绑定深度缓冲区到帧缓冲区 glMatrixMode(GL_PROJECTION); // 改变矩阵变换模式到投影矩阵，以后的矩阵操作都会是对投影矩阵操作 GLfloat w = 0.5 * tanf(M_PI / 8);glFrustumf(-w, w, -w*height/width, w*height/width, 0.5, 3000); // 视锥定义glViewport(0, 0, width, height); // 视口定义 |
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- (void)getViewMatrix:(GLfloat *)matrix{ GLfloat x = _orientation.x; GLfloat y = _orientation.y; GLfloat z = _orientation.z; GLfloat w = _orientation.w; GLfloat *rot = malloc(sizeof(GLfloat) * 16); rot[0] = 1-2*y*y-2*z*z; rot[1] = 2*x*y-2*w*z; rot[2] = 2*x*z+2*w*y; rot[3] = 0.0; rot[4] = 2*x*y+2*w*z; rot[5] = 1-2*x*2-2*z*z; rot[6] = 2*y*z-2*w*x; rot[7] = 0.0; rot[8] = 2*x*z-2*w*y; rot[9] = 2*y*z+2*w*z; rot[10] = 1-2*x*x-2*y*y; rot[11] = 0.0; rot[12] = 0; rot[13] = 0; rot[14] = 0; rot[15] = 1.0; GLfloat transX = -rot[0]*_position.x - rot[4]*_position.y - rot[8]*_position.z; GLfloat transY = -rot[1]*_position.x - rot[5]*_position.y - rot[9]*_position.z; GLfloat transZ = -rot[2]*_position.x - rot[6]*_position.y - rot[10]*_position.z; rot[12] = transX; rot[13] = transY; rot[14] = transZ; memcpy(matrix, rot, sizeof(GLfloat)*16); free(rot);} |
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- (void)getViewMatrix:(GLfloat *)matrix{ GLfloat x = _orientation.x; GLfloat y = _orientation.y; GLfloat z = _orientation.z; GLfloat w = _orientation.w; GLfloat *rot = malloc(sizeof(GLfloat) * 16); rot[0] = 1-2*y*y-2*z*z; rot[1] = 2*x*y-2*w*z; rot[2] = 2*x*z+2*w*y; rot[3] = 0.0; rot[4] = 2*x*y+2*w*z; rot[5] = 1-2*x*2-2*z*z; rot[6] = 2*y*z-2*w*x; rot[7] = 0.0; rot[8] = 2*x*z-2*w*y; rot[9] = 2*y*z+2*w*z; rot[10] = 1-2*x*x-2*y*y; rot[11] = 0.0; rot[12] = 0; rot[13] = 0; rot[14] = 0; rot[15] = 1.0; GLfloat transX = -rot[0]*_position.x - rot[4]*_position.y - rot[8]*_position.z; GLfloat transY = -rot[1]*_position.x - rot[5]*_position.y - rot[9]*_position.z; GLfloat transZ = -rot[2]*_position.x - rot[6]*_position.y - rot[10]*_position.z; rot[12] = transX; rot[13] = transY; rot[14] = transZ; memcpy(matrix, rot, sizeof(GLfloat)*16); free(rot);} |
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- (void)render{ glBindRenderbufferOES(GL_RENDERBUFFER_OES, _renderbuffer); // 绑定绘制缓冲区到渲染管线 //glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // 清空绘制缓冲区和深度缓冲区 glEnableClientState(GL_VERTEX_ARRAY); MZGLCamera *camera = self.camera; GLfloat *matrix = malloc(sizeof(GLfloat) * 16); [camera getViewMatrix:matrix]; glMatrixMode(GL_MODELVIEW_MATRIX); // 改变矩阵变换模式到模型矩阵 glLoadIdentity(); // 将模型矩阵更新为单位矩阵 glEnable(GL_DEPTH_TEST); // 开始深度测试 glDepthFunc(GL_LESS); // 切换深度测试模式为待绘制像素距离屏幕距离小于深度缓冲区当前值则绘制，否则不绘制 glLoadMatrixf(matrix); // 根据摄像机位置设置模型矩阵，此处的矩阵为摄像机世界矩阵的逆矩阵 glVertexPointer(3, GL_FLOAT, 0, _lineVertexBuffer); glColor4f(1.0, 1.0, 0.0, 1.0); glDrawElements(GL_LINES, _lineVertexCount, GL_UNSIGNED_BYTE, _lineIndexBuffer); // 绘制世界坐标系的坐标轴 glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); // 开启纹理绘制 glEnable(GL_ALPHA_TEST); // 开启Alpha测试 glAlphaFunc(GL_GREATER, 0.5f); // 切换Alpha测试模式为不透明度大于0.5则绘制，否则不绘制 glColor4f(1.0, 1.0, 1.0, 1.0); // 填充绘制缓冲区 NSArray *values = [self.entityDictionary allValues]; for (NSObject *entity in values) { if ([entity conformsToProtocol:@protocol(MZGLRenderable)]) { if ([entity isKindOfClass:[MZGLBillboard class]]) { MZGLBillboard *billboard = (MZGLBillboard *)entity; glVertexPointer(3, GL_FLOAT, 0, billboard.vertexBuffer); // 设置顶点缓冲指针 glTexCoordPointer(2, GL_FLOAT, 0, billboard.coordinates); // 设置纹理坐标指针 [billboard preRender:self]; glLoadIdentity(); GLfloat *transform = [billboard worldTrasform]; // 设置模型世界矩阵 glLoadMatrixf(matrix); // 将模型矩阵设置为摄像机世界矩阵的逆矩阵 glMultMatrixf(transform); // 右乘模型的世界矩阵 [billboard.texure bind]; // 绑定纹理 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); // 绘制顶点 } } } [_context presentRenderbuffer:GL_RENDERBUFFER]; // 绘制到绘制缓冲区} |
下面是在测试数据在模拟器上的效果，后续会说明如何结合陀螺仪去将虚拟世界中的摄像头和设备绑定到一起
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原文地址：http://www.cnblogs.com/xuejinhui/p/4337529.html
