Question

我想在交错的OpenGL vbo中存储三个浮点值和两个字节值。不幸的是，渲染的数据显然是不正确的。当我使用两个不同的VBO渲染相同的数据时，它们都可以正常工作，因此我不认为着色器有问题。

/*
 * 20^3 blocks per chunk, 6 faces per block, 3 vertices per face
 * max. every second face can be visible
 */
private static final int MAX_FLOAT_AMOUNT = 20 * 20 * 20 * 6 * 3 / 2;

/*
 * 20^3 blocks per chunk, 6 faces per block, 2 bytes per face
 * max. every second face can be visible
 */
private static final int MAX_BYTE_AMOUNT = 20 * 20 * 20 * 6 * 2 / 2;

private int dataVboIndex;

protected int vaoId;
protected int indicesCount;

protected boolean isInitialized = false;


public static ByteBuffer dataFloatBuffer = BufferUtils.createByteBuffer(4 * MAX_FLOAT_AMOUNT + MAX_BYTE_AMOUNT);

DefaultChunkVao(int indiciesVboId) {
    init();
}

DefaultChunkVao(boolean initialize) {
    if(initialize) init();
}

private void init() {
    isInitialized = true;

    // bind vao
    vaoId = glGenVertexArrays();
    glBindVertexArray(vaoId);

    //create vbo
    dataVboIndex = glGenBuffers();
    glBindBuffer(GL_ARRAY_BUFFER, dataVboIndex);

    dataFloatBuffer.clear();
    dataFloatBuffer.position(4 * MAX_FLOAT_AMOUNT + MAX_BYTE_AMOUNT);
    dataFloatBuffer.flip();

    // allocate memory
    glBufferData(GL_ARRAY_BUFFER, dataFloatBuffer, GL_STREAM_DRAW);

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, false, 3 * 4 + 2, 0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 1, GL_UNSIGNED_BYTE, false, 3 * 4 + 2, 3 * 4);
    glEnableVertexAttribArray(2);
    glVertexAttribPointer(2, 1, GL_UNSIGNED_BYTE, false, 3 * 4 + 2, 3 * 4 + 1);

    // unbind vao
    glBindVertexArray(0);
}

public void updateData(float[] data) {
    if(!isInitialized) init();

    dataFloatBuffer.clear();
    for(int counter = 0; counter < data.length; counter+=0) {
        dataFloatBuffer.putFloat(data[counter++]);
        dataFloatBuffer.putFloat(data[counter++]);
        dataFloatBuffer.putFloat(data[counter++]);

        dataFloatBuffer.put((byte) data[counter++]);
        dataFloatBuffer.put((byte) data[counter++]);
    }
    dataFloatBuffer.flip();

    glBindBuffer(GL_ARRAY_BUFFER, dataVboIndex);
    glBufferSubData(GL_ARRAY_BUFFER, 0, dataFloatBuffer);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    this.indicesCount = data.length / 5;
}

MAX_FLOAT_AMOUNT和MAX_BYTE_AMOUNT常量包含浮点数。每个VBO个字节。我是否假设在确定ByteBuffer的容量时必须将浮点数乘以4，因为每个浮点数都有4个字节，对吗？

在着色器中我的字节值始终为0，我犯了什么错？

编辑：我能够用一个简单的例子重现该问题。在这里，我想将位置和两个字节存储在VBO中。在片段着色器中，我检查byte1值是否正确传递。如果是这样，则着色器会将形状渲染为绿色，否则为蓝色。不幸的是，我的形状被渲染为蓝色，因此我认为byte1值未正确传递。

vertexShader

#version 400 core

in vec3 position;
in int byte1;
in int byte2;

flat out int p_byte1;
flat out int p_byte2;

void main(void) {

    gl_Position = vec4(position, 1);

    p_byte1 = byte1;
    p_byte2 = byte2;
}

fragmentShader ：

#version 400 core

flat in int p_byte1;
flat in int p_byte2;

out vec3 out_color;

void main(void) {
    if(p_byte1 == 45) {
        out_color = vec3(0, 1, 0);
    } else out_color = vec3(0, 0, 1);

}

创建VAO：

vaoId = glGenVertexArrays();
glBindVertexArray(vaoId);
final int vbo = glGenBuffers();
glBindBuffer(GL_ARRAY_BUFFER, vbo);

float[] data = {0, 0, 0, 20f, 20f, 1, 1, 1, 20f, 20f, 1, 0, 1, 20f, 20f, 0, 1, 1, 20f, 20f};
ByteBuffer dataBuffer = BufferUtils.createByteBuffer(4 * (3 * 4) + 1 * (2 * 4));
for(int counter = 0; counter < data.length; counter+=0) {
dataBuffer.putFloat(data[counter++]);
dataBuffer.putFloat(data[counter++]);
dataBuffer.putFloat(data[counter++]);

dataBuffer.put((byte) data[counter++]);
dataBuffer.put((byte) data[counter++]);
}
dataBuffer.flip();

glBufferData(GL_ARRAY_BUFFER, dataBuffer, GL_STREAM_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 3 * 4 + 2, 0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 1, GL_UNSIGNED_BYTE, false, 3 * 4 + 2, 3 * 4);
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 1, GL_UNSIGNED_BYTE, false, 3 * 4 + 2, 3 * 4 + 1);

glBindVertexArray(0);

Answer 1

我能够找到问题的解决方案。对于整数数据类型，必须使用glVertexAttribIPointer而不是glVertexAttribPointer。

glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 3 * 4 + 2, 0);
glEnableVertexAttribArray(1);
glVertexAttribIPointer(1, 1, GL_UNSIGNED_BYTE, 3 * 4 + 2, 3 * 4);
glEnableVertexAttribArray(2);
glVertexAttribIPointer(2, 1, GL_UNSIGNED_BYTE, 3 * 4 + 2, 3 * 4 + 1);

带浮点和字节的交错VBO

1 个答案: