Question

我想绘制一堆四边形。

现在我有问题;绘图工作正常，但很快，但我使用std :: vector作为我的四边形的容器，他们真的非常非常慢。来自XNA我想我应该创建类似spriteBatch的东西，这样我就可以调用DrawQuad（）将给定的四边形添加到列表中，然后最后调用End（）来绘制每个四边形。

我当前的代码通常会将这样的内容输出到控制台：

DrawQuad(): 77
End(): 0

一遍又一遍。

Main.cpp（sf :: Clock是SFML中的时钟类）

sf::Clock time;
for (int y = 0; y < 100; y++)
    for (int x = 0; x < 100; x++)
        renderer.DrawQuad("A", Vector2<GLfloat>(-1.0f + x * 0.02f, -1.0f + y * 0.02f));
std::cout << "DrawQuad(): " << time.getElapsedTime().asMilliseconds() << std::endl;

Renderer.cpp：

void TextRenderer::DrawQuad(string text, Vector2<GLfloat> position)
{
    //TOP LEFT
    vertexBufferVector.push_back(position.X);
    vertexBufferVector.push_back(position.Y);

    //TOP RIGHT
    vertexBufferVector.push_back(position.X + 0.02f);
    vertexBufferVector.push_back(position.Y);

    //BOTTOM RIGHT
    vertexBufferVector.push_back(position.X + 0.02f);
    vertexBufferVector.push_back(position.Y + 0.02f);

    //BOTTOM LEFT
    vertexBufferVector.push_back(position.X);
    vertexBufferVector.push_back(position.Y + 0.02f);

    int elementCount = elementBufferVector.size() / 6; 

    elementBufferVector.push_back(elementCount * 4);
    elementBufferVector.push_back(elementCount * 4 + 1);
    elementBufferVector.push_back(elementCount * 4 + 2);

    elementBufferVector.push_back(elementCount * 4 + 2);
    elementBufferVector.push_back(elementCount * 4 + 3);
    elementBufferVector.push_back(elementCount * 4);
}

void TextRenderer::End()
{
    sf::Clock time;

    GLfloat* vertexArray = &vertexBufferVector[0];
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * vertexBufferVector.size(), vertexArray, GL_STATIC_DRAW);

    GLint* elementArray = &elementBufferVector[0];
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLint) * elementBufferVector.size(), elementArray, GL_STATIC_DRAW);

    glDrawElements(GL_TRIANGLES, elementBufferVector.size(), GL_UNSIGNED_INT, 0);

    vertexBufferVector.clear();
    elementBufferVector.clear();

    std::cout << "End(): " << time.getElapsedTime().asMilliseconds() << std::endl;
}

知道自己在做什么的人如何解决这个问题？ 10000个四边形真的应该不是问题。

写完所有这些之后，我也将循环从（100,100）增加到（1000,100），现在绘图需要4-5毫秒，这被认为是好的吗？我在想不...

Answer 1

由于这已经死了，我只会回答我的问题，也许它会对某人有所帮助。

我没有使用向量，而是使用了具有设置大小的数组。这使得100000四边形（也有纹理）的总渲染时间降至平均约3.260毫秒。

我的.h现在看起来像这样：

const int MAX_BUFFER_SIZE = 1000;
const int MAX_VERTEX_BUFFER_SIZE = MAX_BUFFER_SIZE * 16;
const int MAX_ELEMENT_BUFFER_SIZE = MAX_BUFFER_SIZE * 6;

...

GLint vertexBufferArrayInserts;
GLfloat vertexBufferArray[MAX_VERTEX_BUFFER_SIZE];
GLint elementBufferArray[MAX_ELEMENT_BUFFER_SIZE];

.cpp文件的相关部分：

void TextRenderer::DrawQuad(Vector2<GLfloat> position)
{
    if(vertexBufferArrayInserts == MAX_BUFFER_SIZE)
        End();

    //TOP LEFT
    vertexBufferArray[vertexBufferArrayInserts * 16] = position.X;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 1] = position.Y;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 2] = 0.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 3] = 0.0f;

    //TOP RIGHT
    vertexBufferArray[vertexBufferArrayInserts * 16 + 4] = position.X + 16.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 5] = position.Y;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 6] = 24.0f / 512.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 7] = 0.0f;

    //BOTTOM RIGHT
    vertexBufferArray[vertexBufferArrayInserts * 16 + 8] = position.X + 16.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 9] = position.Y + 16.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 10] = 24.0f / 512.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 11] = 32.0f / 512.0f;

    //BOTTOM LEFT
    vertexBufferArray[vertexBufferArrayInserts * 16 + 12] = position.X;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 13] = position.Y + 16.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 14] = 0.0f;
    vertexBufferArray[vertexBufferArrayInserts * 16 + 15] = 32.0f / 512.0f;


    //ELEMENT BUFFER
    elementBufferArray[vertexBufferArrayInserts * 6] = vertexBufferArrayInserts * 4;
    elementBufferArray[vertexBufferArrayInserts * 6 + 1] = vertexBufferArrayInserts * 4 + 1;
    elementBufferArray[vertexBufferArrayInserts * 6 + 2] = vertexBufferArrayInserts * 4 + 2;
    elementBufferArray[vertexBufferArrayInserts * 6 + 3] = vertexBufferArrayInserts * 4 + 2;
    elementBufferArray[vertexBufferArrayInserts * 6 + 4] = vertexBufferArrayInserts * 4 + 3;
    elementBufferArray[vertexBufferArrayInserts * 6 + 5] = vertexBufferArrayInserts * 4;

    vertexBufferArrayInserts++;
}

void TextRenderer::End()
{
    glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(GLfloat) * vertexBufferArrayInserts * 16, vertexBufferArray);

    glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, sizeof(GLint) *  vertexBufferArrayInserts * 6, elementBufferArray);

    glDrawElements(GL_TRIANGLES, vertexBufferArrayInserts * 6, GL_UNSIGNED_INT, 0);

    vertexBufferArrayInserts = 0;
}

这就是我计时的方式：

sf::Clock timer;
renderer.Begin(projMatrix);

for (int y = 0; y < 100; y++)
    for(int x = 0; x < 1000; x++)
        renderer.DrawQuad(Vector2<GLfloat>(16.0f * x, 16.0f * y));

renderer.End();

avgDrawTime += timer.getElapsedTime().asMicroseconds();
drawCalls++;

if(drawCalls % 100 == 0)
    std::cout << avgDrawTime / drawCalls << std::endl;

使用std :: vector作为顶点/元素列表与OpenGL

1 个答案: