在 OpenGL ES 1.1 中将多个纹理绑定到一个网格

发布于 2024-11-26 03:06:09 字数 205 浏览 3 评论 0原文

如果我有一个网格（例如有 6 个面的立方体，每个面分别由 4 个顶点组成，总共 24 个顶点），并且我想对每个面应用不同的纹理，我该怎么做？目前，我使用 glDrawElements() 一次绘制整个网格（立方体的所有 6 个面），将所有索引提供到一个缓冲区中。我看不到在绘图时将纹理应用于索引子集的方法。我是否必须拆分索引，逐个绘制每个面，重新绑定每个面之间的纹理，或者是否有更雄辩的解决方案？

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梦幻的味道 2024-12-03 03:06:09

是的，您必须以不同的方式渲染每个面（相应地将其分割并绑定每个面的纹理）。它并不优雅，也不漂亮，但如果您的索引位于自己的元素缓冲区（GL 缓冲区，而不是 ShortBuffer 或类似的东西）中，那么它相当简单。您只需使用glDrawElements 指定缓冲区中的偏移量以及为每个面绘制的三角形数量即可。然后它会像这样（伪代码）：

static class IndexRange
{
    public int offset
    public int numIndices
}

// ... later, down the hall and to the left ...

int faceTextures[] = {tex0, tex1, tex2, ...}
IndexRange faceIndices[] = {face0, face1, face2, ...}

// setup buffers and all that jazz

for (index = 0; index < numFaces; ++index)
{
    IndexRange face = faceIndices[index]
    int texture = faceTextures[index]

    glBindTexture(GL_TEXTURE_2D, texture)
    glDrawElements(GL_TRIANGLES, face.numIndices, GL_UNSIGNED_SHORT, face.offset)
}

如果您使用 ShortBuffer 或类似的东西，我不完全确定您会如何去做，但我想你可能可以根据需要切片它并获得必要的每个不同纹理的面的缓冲区。无论哪种方式，过程都保持相对相同：分割网格并为每个面绑定纹理并仅绘制与该面相对应的索引。

Yes, you will have to render each face differently (split it up accordingly and bind the texture for each face). It's not elegant and it's not pretty, but it's fairly simple if you have your indices in their own element buffer (a GL buffer, not a ShortBuffer or something like that). You can just specify the offset into the buffer using glDrawElements and the number of triangles to draw for each face. Then it goes something like this (pseudocode):

static class IndexRange
{
    public int offset
    public int numIndices
}

// ... later, down the hall and to the left ...

int faceTextures[] = {tex0, tex1, tex2, ...}
IndexRange faceIndices[] = {face0, face1, face2, ...}

// setup buffers and all that jazz

for (index = 0; index < numFaces; ++index)
{
    IndexRange face = faceIndices[index]
    int texture = faceTextures[index]

    glBindTexture(GL_TEXTURE_2D, texture)
    glDrawElements(GL_TRIANGLES, face.numIndices, GL_UNSIGNED_SHORT, face.offset)
}

If you're using a ShortBuffer or something like that, I'm not entirely sure how you'd go about doing that, but I imagine you could probably slice it as needed and get the necessary buffers for each differently-textured face. Either way, the process remains relatively the same: split up the mesh and for each face, bind the texture and draw only those indices corresponding to that face.

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