ios - OpenGL ES 顶点数组对象和奇怪的工件

Question

我正在渲染一个场景，只要方向发生变化就必须重建场景，以便适本地填充屏幕。场景渲染了一些普通彩色四边形的顶点数组对象和一组带纹理的顶点数组对象。所有这些绘图元素，包括任何着色器和相关的顶点数组、索引等都包含在一个类中，所以我每次都把这个类吹走，并在旋转时做一个新的分配/初始化。

首次创建场景时，一切看起来都很好。然而，出于某种原因且没有明显的模式，怪异的三角形可能出现在任何后续旋转中。对于特定场景，每次加载时的发生似乎都是确定性的。然而，从一个场景到另一个场景，有时会出现人工制品，有时一切看起来都很可爱。

我不知道我是如何破坏我的内存(即使在 ARC 中，我需要释放一些内存)还是我如何创建我的 VAO。但是，由于只有当我拆除场景并重建它时才会出现问题...然后我开始按照这个思考过程再次旋转我的轮子。

我有很多代码，所以这里是一些(希望)相关的代码。

这是彩色四边形 VAO 的一些绘图代码。我正在向 NSMutableArray 添加顶点，因为我不知道会有多少个四边形。

- (void) buildNode : (NSDictionary *) nodeDictionary
            bounds : (BoundsGL) bounds
{
    if (!nodeDictionary)
    {
        return;
    }

    NSString *jobidstr = [nodeDictionary objectForKey:kNodeJobidKey];
    NSInteger jobid = jobidstr == NULL ? -1 : [jobidstr intValue];

    NSString *colorHexStr = [nodeDictionary objectForKey:kNodeColorKey];
    ColorGL color = HexidecimalStringToColorGL(colorHexStr);


    //
    // indices

    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count]];
    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count+1]];
    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count+2]];
    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count+2]];
    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count+1]];
    [_coloredQuadIndices addObject:[NSNumber numberWithInt:_coloredQuadVertices.count+3]];


    //
    // vertices

    GLfloat x2 = bounds.pos.x + bounds.size.w;
    GLfloat y2 = bounds.pos.y + bounds.size.h;

    PointGL blp = {bounds.pos.x, bounds.pos.y};
    PointGL brp = {x2, bounds.pos.y};
    PointGL tlp = {bounds.pos.x, y2};
    PointGL trp = {x2, y2};

    ColoredVertex bl = { .pos = blp, .color = color };
    ColoredVertex br = { .pos = brp, .color = color };
    ColoredVertex tl = { .pos = tlp, .color = color };
    ColoredVertex tr = { .pos = trp, .color = color };

    NSValue *tlv = [NSValue valueWithBytes:&tl objCType:@encode(ColoredVertex)];
    NSValue *blv = [NSValue valueWithBytes:&bl objCType:@encode(ColoredVertex)];
    NSValue *trv = [NSValue valueWithBytes:&tr objCType:@encode(ColoredVertex)];
    NSValue *brv = [NSValue valueWithBytes:&br objCType:@encode(ColoredVertex)];
    [_coloredQuadVertices addObject:tlv];
    [_coloredQuadVertices addObject:blv];
    [_coloredQuadVertices addObject:trv];
    [_coloredQuadVertices addObject:brv];
}

为带纹理的四边形创建 VAO 的一些代码:

#import "TexturedQuadVAO.h"
#import "Texture.h"
#import "ShaderUtil.h"

@interface TexturedQuadVAO()
{
    GLuint _textureUniformLocation;
}

@property (strong, nonatomic) Texture *texture;

@end


@implementation TexturedQuadVAO

@synthesize vaoid = _vaoid;

@synthesize vertexBuffer = _vertexBuffer;
@synthesize vcount = _vcount;
@synthesize vsize = _vsize;

@synthesize indexBuffer = _indexBuffer;
@synthesize icount = _icount;
@synthesize isize = _isize;

@synthesize texture = _texture;

- (id) initWithData : (TexturedVertex *) vertices
   numberOfVertices : (NSUInteger) vcount
       verticesSize : (size_t) vsize
            indices : (GLushort *) indices
    numberOfIndices : (NSUInteger) icount
        indicesSize : (size_t) isize
           viewSize : (CGSize) viewSize
               text : (NSString *) text
        textureSize : (SizeGL) textureSize
    foregroundColor : (UIColor *) fgcolor
    backgroundColor : (UIColor *) bgcolor
textureUniformLocation : (GLuint) textureUniformLocation
{
    self = [super init];

    if (self)
    {
        //
        // geometry

        self.vcount = vcount;
        self.vsize = vsize;

        self.icount = icount;
        self.isize = isize;


        //
        // texture

        self.texture = [[Texture alloc] init];
        UIFont *font = [UIFont fontWithName:@"Arial" size:24];
        SizeGL tSize = {textureSize.w * 2.5, textureSize.h * 2.5};
        UIImage *img = createTextImage(viewSize, text, tSize, font, fgcolor, bgcolor);

        [self.texture setupTextureWithImage:img];


        //
        // for shaders
        _textureUniformLocation = textureUniformLocation;


        [self createVertexArrayObject:vertices indices:indices];
    }

    return self;
}

- (void) createVertexArrayObject : (TexturedVertex *) vertices
                         indices : (GLushort *) indices
{
    checkGLError(@"  TexturedQuadVAO createVertexArrayObject ");

    // vertex array object

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


    //
    // vertices buffer

    GLuint vb;
    glGenBuffers(1, &vb);
    self.vertexBuffer = vb;
    glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, self.vsize, vertices, GL_STATIC_DRAW);   // copy data into buffer object

    // position vertex attribute
    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glVertexAttribPointer(GLKVertexAttribPosition, 2, GL_FLOAT, GL_FALSE, sizeof(TexturedVertex), (const GLvoid *) offsetof(TexturedVertex, pos));

    // color vertex attribute
    glEnableVertexAttribArray(GLKVertexAttribColor);
    glVertexAttribPointer(GLKVertexAttribColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(TexturedVertex), (const GLvoid *) offsetof(TexturedVertex, color));

    // textures vertex attribute
    glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
    glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, sizeof(TexturedVertex), (const GLvoid  *) offsetof(TexturedVertex, texcoord));


    //
    // index data buffer

    GLuint ib;
    glGenBuffers(1, &ib);
    self.indexBuffer = ib;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, self.isize, indices, GL_STATIC_DRAW); // copy index data into buffer object


    //
    // clear binds

    glBindVertexArrayOES(0);        // ok to unbind for now, and bind when we want to render
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    checkGLError(@"2 TexturedQuadVAO createVertexArrayObject ");
}

- (void) render
{
    checkGLError(@"  TexturedQuadVAO ");

    glBindVertexArrayOES(_vaoid);
    checkGLError(@"2 TexturedQuadVAO ");

    glActiveTexture(GL_TEXTURE0);
    checkGLError(@"3 TexturedQuadVAO ");

    [self.texture bind];
    checkGLError(@"4 TexturedQuadVAO ");

    glUniform1i(_textureUniformLocation, 0);
    checkGLError(@"5 TexturedQuadVAO ");

    //glDrawElements(GL_TRIANGLE_STRIP, self.vsize/sizeof(GLshort), GL_UNSIGNED_SHORT, 0);
    glDrawElements(GL_TRIANGLE_STRIP, self.vsize/sizeof(GLushort), GL_UNSIGNED_SHORT, 0);
    checkGLError(@"6 TexturedQuadVAO ");

    [self.texture unbind];
    checkGLError(@"7 TexturedQuadVAO ");

    glBindVertexArrayOES(0);
    checkGLError(@"8 TexturedQuadVAO ");
}

- (void) tearDown
{
    [self.texture deleteTexture];

    glDeleteBuffers(1, &_vertexBuffer);
    glDeleteBuffers(1, &_indexBuffer);
    glDeleteVertexArraysOES(1, &_vaoid);
}

@end

我的拆解代码:

- (void) tearDown
{
    // VAOs

    for (int i=0; i<_texturedQuadArray.count; i++)
    {
        TexturedVAO *vao = [_texturedQuadArray objectAtIndex:i];
        [vao tearDown];
        vao = nil;
    }
    [_texturedQuadArray removeAllObjects];

    if (_coloredQuadVAO)
    {
       [_coloredQuadVAO tearDown];
       _coloredQuadVAO = nil;
    }

    if (_coloredQuadOutlinesVAO)
    {
       [_coloredQuadOutlinesVAO tearDown];
       _coloredQuadOutlinesVAO = nil;
    }

    // shaders

    if (_shaders.colorShader)
    {
       glDeleteProgram(_shaders.colorShader);
       _shaders.colorShader = 0;
    }

    if (_shaders.textureShader)
    {
       glDeleteProgram(_shaders.textureShader);
       _shaders.textureShader = 0;
    }

    checkGLError(@"Main tearDown");
}

在过去的几天里，我已经在网上搜索并尝试了所有我能想到的方法来找出这个问题，它开始变得非常糟糕。任何想法将不胜感激!

更新:我发现了问题!

正如我所怀疑的那样，我花了这么多天的时间试图在所有错误的地方找到一些非常微不足道的东西!

罪魁祸首是这一行:

glDrawElements(GL_TRIANGLE_STRIP, self.vsize/sizeof(GLushort), GL_UNSIGNED_SHORT, 0);

在我注意到这个乱七八糟的计算并立即将其更改为:

glDrawElements(GL_TRIANGLE_STRIP, self.icount, GL_UNSIGNED_SHORT, 0);

即我改为计算实际的索引数。

Answer 1

正如我所想的那样，我花了这么多天试图在所有错误的地方找到它是一件非常微不足道的事情!

罪魁祸首是 TexturedQuadVAOs 第二组代码中的这一行:

glDrawElements(GL_TRIANGLE_STRIP, self.vsize/sizeof(GLushort), GL_UNSIGNED_SHORT, 0);

在我注意到这个乱七八糟的计算并立即将其更改为:

glDrawElements(GL_TRIANGLE_STRIP, self.icount, GL_UNSIGNED_SHORT, 0);

即我改为计算实际的索引数。