Objective-C iOS-使用GLKit将图像渲染到屏幕上

Question

为了我的一生，我无法在iPhone模拟器屏幕上渲染图像。 我已尽可能简化了我的代码。

以下代码位于ViewController.m中，该类是GLKViewController的扩展类，也是GLKViewDelegate。

- (void)viewDidLoad {
    [super viewDidLoad];

    /*Setup EAGLContext*/
    self.context = [self createBestEAGLContext];
    [EAGLContext setCurrentContext:self.context];

    /*Setup View*/
    GLKView *view = [[GLKView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    view.context = self.context;
    view.delegate = self;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    self.view = view;
}


- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {

    /*Setup GLK effect*/
    self.effect = [[GLKBaseEffect alloc] init];
    self.effect.transform.projectionMatrix = GLKMatrix4MakeOrtho(0, 320, 480, 0, -1, 1);

    glClearColor(0.5, 1, 1, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);

    NSDictionary * options = [NSDictionary dictionaryWithObjectsAndKeys:
                          [NSNumber numberWithBool:YES],
                          GLKTextureLoaderOriginBottomLeft,
                          nil];
    NSError * error;
    NSString *path = [[NSBundle mainBundle] pathForResource:@"soccerball" ofType:@"jpg"];

    GLKTextureInfo * textureInfo = [GLKTextureLoader textureWithContentsOfFile:path options:options error:&error];
    if (textureInfo == nil) {
        NSLog(@"Error loading file: %@", [error localizedDescription]);
    }

    TexturedQuad newQuad;
    newQuad.bl.geometryVertex = CGPointMake(0, 0);
    newQuad.br.geometryVertex = CGPointMake(textureInfo.width, 0);
    newQuad.tl.geometryVertex = CGPointMake(0, textureInfo.height);
    newQuad.tr.geometryVertex = CGPointMake(textureInfo.width, textureInfo.height);

    newQuad.bl.textureVertex = CGPointMake(0, 0);
    newQuad.br.textureVertex = CGPointMake(1, 0);
    newQuad.tl.textureVertex = CGPointMake(0, 1);
    newQuad.tr.textureVertex = CGPointMake(1, 1);

    self.effect.texture2d0.name = textureInfo.name;
    self.effect.texture2d0.enabled = YES;

    GLKMatrix4 modelMatrix = GLKMatrix4Identity;
    modelMatrix = GLKMatrix4Translate(modelMatrix, 100, 200, 0);

    self.effect.transform.modelviewMatrix = modelMatrix;

    [self.effect prepareToDraw];

    long offset = (long)&(newQuad);

    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
    glVertexAttribPointer(GLKVertexAttribPosition, 2, GL_FLOAT, GL_FALSE, sizeof(TexturedVertex), (void *) (offset + offsetof(TexturedVertex, geometryVertex)));
    glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(TexturedVertex), (void *) (offset + offsetof(TexturedVertex, textureVertex)));
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}

和一些使用的结构...

typedef struct {
    CGPoint geometryVertex;
    CGPoint textureVertex;
} TexturedVertex;

typedef struct {
    TexturedVertex bl;
    TexturedVertex br;
    TexturedVertex tl;
    TexturedVertex tr;
} TexturedQuad;

现在唯一有效的是

glClearColor(0.5, 1, 1, 0.0);
glClear(GL_COLOR_BUFFER_BIT);

可以调整背景颜色。 没有“足球”图像。

任何帮助是极大的赞赏。

编辑-TextureVertex CGPoints不正确，所以我修复了它们。 问题仍然存在。

Answer 1

解：

TexturedVertex结构不得使用CGPoint，而应使用GLKVector2。

这是因为存储在这些点中的浮点值存在转换问题。 GLKit期望浮点值具有单点精度，但是CGPoint浮点值具有双点精度，事情变得很奇怪。 此外，此问题仅在iOS 7.0之后出现

有关此问题的更多详细信息，请参阅此处。 OpenGL ES着色器和64位iPhone 5S