OpenGL 缩放顶点数组
我有一个按如下方式绘制的顶点数组（我正在努力将其转换为单个 glDrawArrays 调用，因此这不是这里的问题）：
gl.glVertexPointer(3, GL.GL_FLOAT, 0, buff);
for ( int i = 0; i < numPoints; i++ ) {
gl.glDrawArrays(GL.GL_LINE_LOOP, i*verticesPerPoint, verticesPerPoint);
}
这有效，但我想缩放正在绘制的线循环。我尝试在调用 glDrawArrays 之前调用 glScaled ，但这些点没有显示。我本以为缩放只是将线循环缩放到位，但情况似乎并非如此。
请注意缓冲区中的顶点何时未缩放，因为我希望能够以不同的比例重用相同的缓冲区。我的想法是，我可以将形状重新绘制为恒定的像素大小，而无需在每次传递时重新创建数组。
谁能解释我做错了什么或者这是否可能？
I have a vertex array that I draw as follows (I am working to convert this to a single glDrawArrays call, so that is not the issue here):
gl.glVertexPointer(3, GL.GL_FLOAT, 0, buff);
for ( int i = 0; i < numPoints; i++ ) {
gl.glDrawArrays(GL.GL_LINE_LOOP, i*verticesPerPoint, verticesPerPoint);
}
This works, but I would like to scale the line loops being drawn. I tried calling glScaled before calling glDrawArrays, but then the points don't show up. I would've thought the scaling just scales the line loops in place, but that does not seem to be the case.
Note when the vertices in the buffer are unscaled since I was hoping to be able to reuse the same buffer at different scales. The idea is that I can redraw the shapes a constant pixel size without recreating the array on each pass.
Can anyone explain what I am doing wrong or if this is even possible?
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您确定应用glScale并将当前矩阵模式设置为GL_MODELVIEW矩阵模式吗？如果是这样，它是在任何对象空间变换之前还是之后被调用？使用 glScale[f/d] 是一种合理的方法 - 它将应用于顶点数据 - 但提到“恒定像素大小”表明这可能是一个 2D 问题。在这种情况下，可能值得研究一下 glViewport 的机制。
Are you sure glScale is applied with the current matrix mode set to the GL_MODELVIEW matrix mode? If so, is it being called before or after any object space transforms? Using glScale[f/d] is a sound approach - it will be applied to the vertex data - but the mention of 'constant pixel size' suggests this is perhaps a 2D problem. It might be worth looking at the mechanics of glViewport in that case.