Matrix Palette, Drawing Issue when ModelView Matrix

问题

Using OpenGL 1.1 and the Matrix Palette extension. The issue I'm having, is that not every model being loaded needs to be animated, so I don't think that I need to enable those client states nor provide weights or weight index arrays. For example, I'm trying something like this during my drawing code...

glMatrixMode(GL_MATRIX_PALETTE_OES);

glBindBuffer(GL_ARRAY_BUFFER, dataBuffers[0]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, dataBuffers[1]);

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_WEIGHT_ARRAY_OES);
glEnableClientState(GL_MATRIX_INDEX_ARRAY_OES);

//Code to modify the palettes... works fine...
for(i = 0; i < mech.boneCount; ++i){
    glCurrentPaletteMatrixOES(i);
    glLoadPaletteFromModelViewMatrixOES();

    GenerateBoneMatrixPalette(bones, i);
}

glVertexPointer(3, GL_FLOAT, sizeof(VertexData), (char*)(NULL + 0));
glNormalPointer(GL_FLOAT, sizeof(VertexData), (char*)(NULL + 12));
glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(VertexData), (char*)(NULL + 24));
glWeightPointerOES(1, GL_FLOAT, sizeof(VertexData), (char*)(NULL + 28));
glMatrixIndexPointerOES(1, GL_UNSIGNED_BYTE, sizeof(VertexData), (char*)(NULL + 32));
glDrawElements(GL_TRIANGLES, mech.indexsize, GL_UNSIGNED_SHORT, (char*)(NULL + 0));

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_WEIGHT_ARRAY_OES);
glDisableClientState(GL_MATRIX_INDEX_ARRAY_OES);

glBindBuffer(GL_ARRAY_BUFFER, dataBuffers[2]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, dataBuffers[3]);

glMatrixMode(GL_MODELVIEW);

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);

//pardon the hard 28 value here, it's the correct offset for this test
glVertexPointer(3, GL_FLOAT, 28, (char*)(NULL + 0));
glNormalPointer(GL_FLOAT, 28, (char*)(NULL + 12));
glColorPointer(4, GL_UNSIGNED_BYTE, 28, (char*)(NULL + 24));
glDrawElements(GL_TRIANGLES, indexsize, GL_UNSIGNED_SHORT, (char*)(NULL + 0));

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);

glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

But it is not working. The first section displays correctly but the second does not display at all. If I add an, what feels to be, unnecessary weight and weight index element to the second section modifying the stride as needed and not setting the matrix to the modelview... then it displays what I expect.

The test that feels the strangest, is if I do not enable the Matrix Palette extension at all and only draw the second part, it works just fine. However, just enabling the Matrix Palette extension causes the second section to not work at all, making it seem that I can not draw simply while the mode is set to the ModelView Matrix... though this seems somewhat unusual as the ModelView still absolutely is affected by transformations.

So... is it possible to switch to and draw while the ModelView is the current matrix while using this extension? Or must I make use/reuse a single palette to make it work.

回答1:

I haven't found an OES matrix palette extension in the extension registry, but an ARB extension and suppose it works similar. In this extension, you have to enable GL_MATRIX_PALETTE and or GL_VERTEX_BLEND (with glEnable) to use matrix palette skinning and disable it to not use it.

But the glMatrixMode does't have anything to do with enabling or disabling it. It just selects the matrix to which matrix modification functions apply (like glLoadIdentity, glTranslate, ...).

EDIT: After googling this extension (I have no ES experience) I found, that you definitely have to enable GL_MATRIX_PALETTE_OES to use it (via glEnable) and then disable it again for your second part to not use it. As I've written above, glMatrixMode doesn't do what you thought it to.

来源：https://stackoverflow.com/questions/6106152/matrix-palette-drawing-issue-when-modelview-matrix