如何在iOS5上使用广场上的图像放置2D纹理

这是我在iphone上的第一个应用程序，我正尝试在GLKView中加载纹理。我不使用GLKVIewController类。。经过大量搜索之后，我认为我已经管理将图像加载到2D纹理中，但我仍不确定如何将其映射到矩形。以下是我用来绘制矩形的代码。如何在iOS5上使用广场上的图像放置2D纹理

创建顶点数组：

GLfloat gSqaureVertexData[216] = 
{ 
    // Data layout for each line below is: 
    // positionX, positionY, positionZ,  normalX, normalY, normalZ, 
    0.5f, -0.5f, -0.5f,  0.0f, 0.0f, -1.0f, 
    -0.5f, -0.5f, -0.5f,  0.0f, 0.0f, -1.0f, 
    0.5f, 0.5f, -0.5f,   0.0f, 0.0f, -1.0f, 
    0.5f, 0.5f, -0.5f,   0.0f, 0.0f, -1.0f, 
    -0.5f, -0.5f, -0.5f,  0.0f, 0.0f, -1.0f, 
    -0.5f, 0.5f, -0.5f,  0.0f, 0.0f, -1.0f 
};

初始化在viewDidLoad中的上下文：

context = [[EAGLContext alloc]initWithAPI:kEAGLRenderingAPIOpenGLES2]; 
    CAEAGLLayer *eaglLayer = (CAEAGLLayer*)self.view.layer; 
    eaglLayer.opaque=NO; 

    glView = [[GLKView alloc]initWithFrame:CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y+45, self.view.frame.size.width, self.view.frame.size.height-100.0f)]; 

    glView.context=context; 
    glView.delegate=self; 
    glView.backgroundColor=[UIColor clearColor]; 
    glView.drawableDepthFormat = GLKViewDrawableDepthFormat24; 
    [self setupGL]; 
    [self.view addSubview:glView];

加载png图片到纹理对象和其他安装

-(void) setupGL 
{ 
    [EAGLContext setCurrentContext:context]; 

    //[self loadShaders]; 

    self.effect = [[GLKBaseEffect alloc] init]; 
    //self.effect.light0.enabled = GL_TRUE; 
    //self.effect.light0.diffuseColor = GLKVector4Make(1.0f, 0.4f, 0.4f, 1.0f); 

    glEnable(GL_DEPTH_TEST); 

    glGenVertexArraysOES(1, &_vertexArray); 
    glBindVertexArrayOES(_vertexArray); 

    glGenBuffers(1, &_vertexBuffer); 
    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer); 
    glBufferData(GL_ARRAY_BUFFER, sizeof(gSqaureVertexData), gSqaureVertexData, GL_STATIC_DRAW); 

    glEnableVertexAttribArray(GLKVertexAttribPosition); 
    glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(0)); 
    glEnableVertexAttribArray(GLKVertexAttribNormal); 
    glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(12)); 

    glBindVertexArrayOES(0); 
    glBindTexture(GL_TEXTURE_2D, texture[0]); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

    NSString *path = [[NSBundle mainBundle] pathForResource:@"texture" ofType:@"png"]; 
    NSData *texData = [[NSData alloc] initWithContentsOfFile:path]; 
    UIImage *image = [[UIImage alloc] initWithData:texData]; 
    if (image == nil) 
     NSLog(@"Do real error checking here"); 

    GLuint width = CGImageGetWidth(image.CGImage); 
    GLuint height = CGImageGetHeight(image.CGImage); 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    void *imageData = malloc(height * width * 4); 
    CGContextRef contextTex = CGBitmapContextCreate(imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); 
    CGColorSpaceRelease(colorSpace); 
    CGContextClearRect(contextTex, CGRectMake(0, 0, width, height)); 
    CGContextTranslateCTM(contextTex, 0, height - height); 
    CGContextDrawImage(contextTex, CGRectMake(0, 0, width, height), image.CGImage); 

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData); 

    CGContextRelease(contextTex); 

    free(imageData); 
    [image release]; 
    [texData release];  
}

绘制sqaure在drawInRect：

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect { 
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f); 
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 

    glBindVertexArrayOES(_vertexArray); 

    // Render the object[[ with GLKit 
    [self.effect prepareToDraw]; 

    glDrawArrays(GL_TRIANGLES, 0, 36); 

    // Render the object again with ES2 
    glUseProgram(_program); 

    glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, _modelViewProjectionMatrix.m); 
    glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m); 

    glDrawArrays(GL_TRIANGLES, 0, 36); 
}

来源

2012-07-19 Kunal

你需要添加纹理坐标到每个顶点，设置纹理作为活动纹理并添加顶点属性的纹理坐标：

顶点数据：

//Vertex, Normal, Texture coordinate (ranges from 0 to 1) 
0.5f, -0.5f, -0.5f,  0.0f, 0.0f, -1.0f, 1, 1, 
-0.5f, -0.5f, -0.5f,  0.0f, 0.0f, -1.0f, 0, 1, 
0.5f, 0.5f, -0.5f,   0.0f, 0.0f, -1.0f, 1, 0, 
0.5f, 0.5f, -0.5f,   0.0f, 0.0f, -1.0f, 1, 0, etc

设置活动纹理（这是做它的标准的OpenGL方式，约GLKit不知道）：

glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D, textures[0]);

组纹理属性（可能不完全正确，我不是法米尔与GLKit联系）：

glEnableVertexAttribArray(GLKVertexAttribTexCoord); 
glVertexAttribPointer(GLKVertexAttribTexCoord, 2, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(16));

来源

2013-04-12 16:30:26

如何在iOS5上使用广场上的图像放置2D纹理

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