我正在渲染一个必须在方向发生变化时重建的场景，以便适当地填充屏幕。场景渲染了一些常规彩色四边形的顶点数组对象和一组纹理顶点数组对象。所有这些绘图元素，包括任何着色器和相关的顶点、索引等数组都包含在一个类中，所以我每次都会吹走这个类并在旋转时执行一个新的 alloc/init。
首次创建场景时，一切看起来都很好。然而，由于某种原因并且没有明显的模式，奇怪的三角形可能会出现在任何后续的旋转中。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，有时会出现文物，有时一切看起来都很可爱。
我不知道这是否是我破坏记忆的方式（即使在 ARC 中，我也需要释放其中的一些），还是我创建 VAO 的方式。然而，由于问题仅在我拆除场景并重建它时才会出现......然后我开始用这个思考过程再次旋转我的轮子。
我有很多代码，所以这里有一些（希望是）相关代码。
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];
}
为纹理四边形创建 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，我在网上搜索并尝试了我能想到的一切来找出这个问题，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，我花了这么多天试图找到的东西非常微不足道 - 在所有错误的地方！
罪魁祸首是这一行：
glDrawElements(GL_TRIANGLE_STRIP, self.vsize/sizeof(GLushort), GL_UNSIGNED_SHORT, 0);
在我注意到这个混乱的计算并立即将其更改为：
glDrawElements(GL_TRIANGLE_STRIP, self.icount, GL_UNSIGNED_SHORT, 0);
即我改为计数到实际指数计数。