今天下午，当我从使用 VBO 转移到 VAO / VBO 时，我一直在努力说服我的 openGLES2.0 代码正确执行。基本上，我正在努力通过苹果关于 openGLES 的“专家”建议，并转向使用顶点数组对象是最重要的......
我在这里查看了类似的问题和回复，但这似乎对我没有帮助，除了再次向我保证其他人遇到类似的问题:(
我的场景是我有大约 500 个矩形纹理在屏幕上移动。没有 VAO，代码一切正常，但是当我定义 USE_VAO（我的常量）时，它在第一次绘制元素调用时崩溃。我显然没有正确理解 VAO ......但我看不到我的方式的错误！
setupBeforeRender 方法在进入渲染循环之前作为我设置的最后一部分被调用。
-(void) setupBeforeRender {
glClearColor(0.6, 0.6, 0.6, 1);
glViewport(0, 0, self.frame.size.width, self.frame.size.height);
glEnable(GL_DEPTH_TEST);
glUniform1i(_textureUniform, 0);
glActiveTexture(GL_TEXTURE0);
glEnableVertexAttribArray(_positionSlot);
glEnableVertexAttribArray(_colorSlot);
glEnableVertexAttribArray(_texCoordSlot);
glGenBuffers(1, &_indexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Indices), Indices, GL_STATIC_DRAW);
}
这是渲染方法
- (void)render:(CADisplayLink*)displayLink {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Model view matrix and projection code removed for clarity
GLsizei stride = sizeof(Vertex);
const GLvoid* colourOffset = (GLvoid *) sizeof(float[3]);
const GLvoid* textureOffset = (GLvoid *) sizeof(float[7]);
for (my objectToDraw in objectToDrawArray)
{
if (objectToDraw.vertexBufferObject == 0)
{
#ifdef USE_VAO
glGenVertexArraysOES(1,&_vao);
glBindVertexArrayOES(_vao);
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, stride, 0);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, stride, colourOffset);
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE,stride, textureOffset);
objectToDraw.vertexBufferObject = [objectToDraw createAndBindVBO];
objectToDraw.vertexArrayObject = _vao;
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArrayOES(0);
#else
objectToDraw.vertexBufferObject = [objectToDraw createAndBindVBO];
#endif
}
// Texture binding removed for clarity
#ifdef USE_VAO
// This code crashes with EXC_BAD_ACCESS on the glDrawElements
glBindVertexArrayOES(objectToDraw.vertexArrayObject);
glDrawElements(GL_TRIANGLES, sizeof(Indices) / sizeof(Indices[0]), GL_UNSIGNED_SHORT,0);
glBindVertexArrayOES(0);
#else
// This path works fine. So turning VAO off works :(
glBindBuffer(GL_ARRAY_BUFFER, storyTile.vertexBufferObject);
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, stride, 0);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, stride, colourOffset);
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE, stride, textureOffset);
glDrawElements(GL_TRIANGLES, sizeof(Indices) / sizeof(Indices[0]), GL_UNSIGNED_SHORT,0);
#endif
} // End for each object
[_context presentRenderbuffer:GL_RENDERBUFFER];
}
最后，我的创建和绑定 VBO 方法如下所示；
-(GLuint) createAndBindVBO {
const float* rgba = CGColorGetComponents([self.colour CGColor]);
Vertex Vertices[] = {
{{0, 1, 0}, {1, 0, 1, 1}, {0,1}},
{{0, 0, 0}, {1, 0, 1, 1}, {0,0}},
{{1, 1, 0}, {1, 0, 1, 1}, {1,1}},
{{1, 0, 0}, {1, 0, 1, 1}, {1,0}}
};
// Code removed for clarity - sets up geometry and colours
GLuint vertexBuffer;
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
return vertexBuffer;
}
我已经尝试了各种排列，并用 glGetError() 散布了代码，看看这是否有助于指出问题出现的地方。唉，除了 drawElements 调用上的 BAD_ACCESS 崩溃之外，我没有收到任何错误。
编辑：正如建议的那样，不幸的是，这也不起作用
objectToDraw.vertexBufferObject = [objectToDraw createVBO];
glGenVertexArraysOES(1,&_vao);
glBindVertexArrayOES(_vao);
glBindBuffer(GL_ARRAY_BUFFER, objectToDraw.vertexBufferObject);
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, stride, 0);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, stride, colourOffset);
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE,stride, textureOffset);
objectToDraw.vertexArrayObject = _vao;
glBindVertexArrayOES(0);
我必须对顶点数组对象做一些愚蠢的事情......但有人能找出问题所在吗？