我有这个函数来绘制一个精灵对象（它只是一个带有像素值数组的对象）：
#include <iostream>
#include <atomic>
class Object
{
public:
Object() // Constructor
{
// initialize the object
// ...
m_objCount++; // Increase object count when creating object (In constructor)
}
Object(const Object& obj) // Copy constructor
{
m_objCount++;
}
Object(Object&&) // Move constructor
{
m_objCount++;
}
~Object()
{
m_objCount--; // Decrease object count when destroying object
}
static int object_count() // Define a static member function to retrive the count
{
return m_objCount;
}
private:
static std::atomic_int m_objCount; // Use static member to store object count,
// use std::atomic_int to make sure it is thread safe
};
std::atomic_int Object::m_objCount; // Initialize static member
int main()
{
Object obj;
// prints "obj count: 1"
std::cout << "obj count: " << obj.object_count() << std::endl; // call object_count() with object
std::cout << "obj count: " << Object::object_count() << std::endl; // call object_count() with class name
}
唯一缺少的是this.draw = (ctx, x, y, scale) => {
let i = 0;
let startIndex, red, green, blue, alpha, currentX, currentY;
while(i < this.size.width * this.size.height){
startIndex = i * 4;
red = this.pixArray[startIndex];
green = this.pixArray[startIndex + 1];
blue = this.pixArray[startIndex + 2];
alpha = this.pixArray[startIndex + 3];
// Draw, but not if the pixel is invisible
if(alpha != 0){
ctx.fillStyle = `rgba(${red}, " + ${green} + ", " + ${blue} + ", " + ${alpha / 255.0} + ")`;
currentX = i % this.size.width;
currentY = (i - currentX) / this.size.width;
ctx.fillRect(Math.round(x + (currentX * scale)), Math.round(y + (currentY * scale)),
Math.round(scale), Math.round(scale));
}
i++;
}
}
，它是Uint8Array的像素值。
然而，表现相当糟糕。我发现画布更改状态（pixArray）会丢失一些性能，但我必须在每次迭代时修改它。即使fillStyle保持不变，性能仍然是不可接受的。我意识到我有选择或预渲染，但我希望避免这种情况。