[英]Offsets for per vertex data interleaved in OpenGL ES on Android
是否可以在Android上的OpenGL ES中使用每個頂點數據交錯?
我無法為normal
和color
成員獲取正確的偏移指針。
在C ++中我會做這樣的事情:
struct ColoredVertexData3D{
Vertex3D vertex;
Vector3D normal;
ColorRGBA color;
};
const ColoredVertexData3D vertexData[] =
{
{
{0.0f, 0.5f, 0.8f}, // Vertex |
{0.0f, 0.4f, 0.6f}, // Normal | Vertex 0
{1.0f, 0.0f, 0.0f, 1.0f} // Color |
},
{
{0.8f, 0.0f, 0.5f}, // Vertex |
{0.6f, 0.0f, 0.4f}, // Normal | Vertex 1
{1.0f, 0.5f, 0.0f, 1.0f} // Color |
},
// ... more vertexes.
};
const int stride = sizeof(ColoredVertexData3D);
glVertexPointer(3, GL_FLOAT, stride, &vertexData[0].vertex);
glColorPointer(4, GL_FLOAT, stride, &vertexData[0].color);
glNormalPointer(GL_FLOAT, stride, &vertexData[0].normal);
在Android上用Java做同樣的事情嗎? 這就是我目前得到的:
ByteBuffer vertexData = ...;
int stride = 40;
gl.glVertexPointer(3, GL10.GL_FLOAT, stride, vertexData);
// This obviously doesn't work. ------------v
gl.glColorPointer(4, GL10.GL_FLOAT, stride, &vertexData[0].color);
gl.glNormalPointer(GL10.GL_FLOAT, stride, &vertexData[0].normal);
基本思想是在ByteBuffer上調用duplicate(),它創建一個新的ByteBuffer,它共享底層存儲但允許你從不同的位置開始。
這對我有用:
FloatBuffer verticesNormals;
// ... code to initialize verticesNormals ...
// verticesNormals contains 6 floats for each vertex. The first three
// define the position and the next three define the normal.
gl.glVertexPointer(3, gl.GL_FLOAT, 24, verticesNormals);
// Create a buffer that points 3 floats past the beginning.
FloatBuffer normalData = mVerticesNormals.duplicate();
normalData.position(3);
gl.glNormalPointer(gl.GL_FLOAT, 24, normalData);
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