問題描述

我正在尋求有關理解 VBO 的幫助.我已經進行了大量研究并找到了有關該主題的教程，但它們對我來說仍然含糊不清.我有幾個問題:

I am looking for help with understanding VBOs. I have done a ton of research and have found tutorials on the subject, but they are still vague to me. I have a few questions:

應該在哪里創建 VBO，我應該如何創建?

Where should a VBO be created, and how should I create one?

我目前正在使用下面的代碼來初始化我的頂點和索引緩沖區:

I am currently using the code right below to initialize my vertex and index buffers:

    vertices = new float[]
            {
                    p[0].x, p[0].y, 0.0f,
                    p[1].x, p[1].y, 0.0f,
                    p[2].x, p[2].y, 0.0f,
                    p[3].x, p[3].y, 0.0f,
            };

    // The order of vertex rendering for a quad
    indices = new short[] {0, 1, 2, 0, 2, 3};

    ByteBuffer bb = ByteBuffer.allocateDirect(vertices.length * 4);
    bb.order(ByteOrder.nativeOrder());
    vertexBuffer = bb.asFloatBuffer();
    vertexBuffer.put(vertices);
    vertexBuffer.position(0);

    ByteBuffer dlb = ByteBuffer.allocateDirect(indices.length * 2);
    dlb.order(ByteOrder.nativeOrder());
    drawListBuffer = dlb.asShortBuffer();
    drawListBuffer.put(indices);
    drawListBuffer.position(0);

如果我是正確的，這不是創建 VBO.那么，如果我想制作 VBO，創建 VBO 的代碼會緊跟上面列出的代碼嗎?如果有，如何創建?

If I am correct, this is not creating a VBO. So, if I wanted to make a VBO, would the code to create a VBO go right after the code listed above? If so, how would it be created?

另外，如何將 VBO 渲染和繪制到屏幕上?

Also, how is a VBO rendered and drawn to screen?

它的渲染和繪制方式是否與僅使用頂點和索引數組相同?如果不是，流程是什么?目前，我渲染和繪制我的對象，如下面的代碼所示:

Is it rendered and drawn the same way as just using vertex and index arrays? If not, what is the process? Currently, I render and draw my objects as shown in the code below:

    GLES20.glUseProgram(GraphicTools.sp_SolidColor);

    mPositionHandle =
            GLES20.glGetAttribLocation(GraphicTools.sp_SolidColor, "vPosition");

    GLES20.glEnableVertexAttribArray(mPositionHandle);

    GLES20.glVertexAttribPointer(mPositionHandle, 3,
            GLES20.GL_FLOAT, false,
            0, vertexBuffer);

    mtrxHandle = GLES20.glGetUniformLocation(GraphicTools.sp_SolidColor,
            "uMVPMatrix");

    GLES20.glUniformMatrix4fv(mtrxHandle, 1, false, m, 0);

    GLES20.glDrawElements(GLES20.GL_TRIANGLES, indices.length,
            GLES20.GL_UNSIGNED_SHORT, drawListBuffer);

    GLES20.glDisableVertexAttribArray(mPositionHandle);

如果您有任何問題，請告訴我.提前致謝.

If you have any questions, let me know. Thanks in advance.

推薦答案

A 頂點緩沖區Object 是一個可以存儲頂點數組數據的緩沖區.數據一次性上傳到圖形內存(GPU)，可重復用于繪制網格.

A Vertex Buffer Object is a buffer where vertex array data can be stored. The data are uploaded one time to the graphics memory (GPU) and can be used repeatedly to draw a mesh.

首先，您必須創建 2 個緩沖區對象，一個用于頂點，一個用于索引:

First you have to create 2 buffer objects, one for the vertices and one for the indices:

int buffers[] = new int[2];
GLES20.glGenBuffers(2, buffers, 0);
int vbo = buffers[0];
int ibo = buffers[1];

然后你必須綁定緩沖區并傳輸數據

Then you have to bind the buffer and to transfer the data

GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo);
GLES20.glBufferData(
    GLES20.GL_ARRAY_BUFFER,
    vertexBuffer.capacity() * 4, // 4 = bytes per float
    vertexBuffer,
    GLES20.GL_STATIC_DRAW);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);

GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, ibo);
GLES20.glBufferData(
    GLES20.GL_ELEMENT_ARRAY_BUFFER,
    drawListBuffer.capacity() * 2, // 2 = bytes per short
    drawListBuffer,
    GLES20.GL_STATIC_DRAW);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

如果要繪制網格，則必須定義通用頂點屬性數據數組并綁定索引緩沖區，但不必將任何數據傳輸到 GPU:

If you want to draw the mesh, then you have to define the array of generic vertex attribute data and you have to bind the index buffer, but you don't have to transfer any data to the GPU:

GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo);
GLES20.glVertexAttribPointer(
        mPositionHandle, 3,
        GLES20.GL_FLOAT, false,
        0, 0);                        // <----- 0, because "vbo" is bound
GLES20.glEnableVertexAttribArray(mPositionHandle);

GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, ibo);
GLES20.glDrawElements(
    GLES20.GL_TRIANGLES, indices.length,
    GLES20.GL_UNSIGNED_SHORT, 0);     // <----- 0, because "ibo" is bound

GLES20.glDisableVertexAttribArray(mPositionHandle);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

另見 頂點緩沖區簡介對象(VBO)

這篇關于如何在 OpenGL ES 2 中創建和使用 VBO的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！