OpenGL ES不再显示对象

I am new to OpenGL ES programming. I found a good tutorial to start and the project displayed a square. I then tried to move the most OpenGL code out of the View Controller to a Model object which would store vertices, color, etc and then in the View Controller I would just call:

我是OpenGL ES编程的新手。我发现了一个很好的教程,项目显示了一个正方形。然后我试图将最多的OpenGL代码从View Controller移动到一个Model对象,它可以存储顶点,颜色等,然后​​在View Controller中我会调用:

[model update];
[model load];

This way it would be more practice if I had several models to display. And since I did this the cube no longer displays on screen. I think I pinpointed to error to the update method where all the model view matrix calculations occur, because when I comment out this method the cube displays but it just fills the screen.

这样,如果我有几个模型可以显示,那将更多练习。自从我这样做后,立方体不再显示在屏幕上。我认为我确定了所有模型视图矩阵计算发生的更新方法的错误,因为当我注释掉这个方法时,立方体会显示,但它只是填满了屏幕。

-(void)update: (int)width And:(int)height{
float aspect = (width/height);
GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(
                                      GLKMathDegreesToRadians(65.0f), aspect,
                                      4.0f, 10.0f);
self.effect.transform.projectionMatrix = projectionMatrix;

GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, 6.0f);   
rotation += 90;
modelViewMatrix = GLKMatrix4Rotate(modelViewMatrix,
                                       GLKMathDegreesToRadians(rotation), 0, 0, 1);
self.effect.transform.modelviewMatrix = modelViewMatrix;
}  

And here is the loading method:

这是加载方法:

- (void)load{
self.effect = [[GLKBaseEffect alloc] init];

NSDictionary * options = [NSDictionary dictionaryWithObjectsAndKeys:
                          [NSNumber numberWithBool:YES],
                          GLKTextureLoaderOriginBottomLeft, 
                          nil];

NSError * error;    
NSString *path = [[NSBundle mainBundle] pathForResource:@"tile_floor" ofType:@"png"];
GLKTextureInfo * info = [GLKTextureLoader textureWithContentsOfFile:path options:options error:&error];
if (info == nil) {
    NSLog(@"Error loading file: %@", [error localizedDescription]);
}
self.effect.texture2d0.name = info.name;
self.effect.texture2d0.enabled = true;

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

glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);

glGenBuffers(1, &indexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Indices), Indices, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribPosition);        
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const GLvoid *) offsetof(Vertex, Position));
glEnableVertexAttribArray(GLKVertexAttribColor);
glVertexAttribPointer(GLKVertexAttribColor, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const GLvoid *) offsetof(Vertex, Color));
glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const GLvoid *) offsetof(Vertex, TexCoord));

glBindVertexArrayOES(0);
}

And here is the rendering method:

这是渲染方法:

- (void)render{
[self.effect prepareToDraw];
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);

glBindVertexArrayOES(vertexArray);
glDrawElements(GL_TRIANGLES, sizeof(Indices)/sizeof(Indices[0]), GL_UNSIGNED_BYTE, 0);
}

Any help would be appreciated. Thanks.

任何帮助,将不胜感激。谢谢。

1 个解决方案

#1

There's not really an 'error' here. The problem is that you're not really setting up the projection and modelview matrices so that it frames your model nicely. There's no magic solution. You should consider the vertices in the model that you are drawing (do they go up to 100? 1000? Just 0.5?) and choose appropriate settings for GLKMatrix4MakePerspective that put them squarely in the screen.

这里没有真正的“错误”。问题是你并没有真正设置投影和模型视图矩阵,以便很好地构建你的模型。没有神奇的解决方案。你应该考虑你正在绘制的模型中的顶点(它们是否达到100?1000?只是0.5?)并选择适当的GLKMatrix4MakePerspective设置,将它们直接放在屏幕上。

As a short cut, (since you said that without the translation and rotation it fills the whole screen), you can replace those transformations with a scale command to scale down the size of the object.

作为捷径,(因为你说没有平移和旋转它会填满整个屏幕),你可以用缩放命令替换这些变换来缩小对象的大小。

Something like:

GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.1f, 0.1f, 0.1f);   

As general advice, try to consider the effect of each command individually. If you're looking for an introduction to projection/transformation concepts, I found this link: http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Chapter-3:-3D-transformation-and-projection.html Skip down to the section called Projection and world space.

作为一般建议,尝试单独考虑每个命令的效果。如果您正在寻找投影/转换概念的介绍,我找到了这个链接:http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Chapter-3:-3D-transformation-and -projection.html跳到名为Projection and world space的部分。