osg传递着色器变量

> I tried using a different attribute index from 0, and the colours are now showing up. I had come across the link earlier that you posted, but didn't realise that was how OpenGL worked (I tested it out in an OpenGL app and got the same problem as in my OSG app, with the slightly deformed mesh and no colours).
>
> So if I use custom attributes and no built in ones, then I shouldn't have this problem of overwriting existing attributes, which I also tested in the OpenGL app, and it allowed me to use 0 for a vertex attrib, and 1 for a colour attrib. So that's what I want to do now in my OSG app. But I cannot get it to work, it just renders nothing. I have tried different attribute values (from '0 and 1', '10 and 11', to '0 and 11'), but to no avail.
>
> I've posted what I believe is the relevant code, maybe I didn't set the vertex data right in the geometry. The code here currently renders nothing.
>
>
> Code:
>
> GLuint vertLoc = 0;
> GLuint colLoc = 1;
>
> //
> osg::Geode* pyramidGeode = new osg::Geode();
> root->addChild(pyramidGeode);
>
> //geometry
> osg::Geometry* pyramidGeometry = new osg::Geometry();
> pyramidGeode->addDrawable(pyramidGeometry);
>
> //vertices
> osg::Vec3Array* pyramidVertices = new osg::Vec3Array;
>
> for(int i=0;i<model->verticesNum;i++) {
> float x = model->positions[i*3];
> float y = model->positions[i*3+1];
> float z = model->positions[i*3+2];
> pyramidVertices->push_back(osg::Vec3(x,y,z));
> }
>
>
> //pyramidGeometry->setVertexArray(pyramidVertices);
>
> program->addBindAttribLocation("a_vertex", vertLoc);
> pyramidGeometry->setVertexAttribArray(vertLoc,pyramidVertices);
> pyramidGeometry->setVertexAttribBinding(vertLoc, osg::Geometry::BIND_PER_VERTEX);
> }
> //colours
> osg::Vec4Array* colors = new osg::Vec4Array;
>
> for(int i=0;i<model->verticesNum;i++) {
> float r = model->cols[i*4];
> float g = model->cols[i*4+1];
> float b = model->cols[i*4+2];
> float a = model->cols[i*4+3];
> colors->push_back(osg::Vec4(r,g,b,a));
> }
>
> program->addBindAttribLocation("a_col", colLoc);
> pyramidGeometry->setVertexAttribArray(colLoc, colors);
> pyramidGeometry->setVertexAttribBinding(colLoc, osg::Geometry::BIND_PER_VERTEX);
> }
>
> //indices
> osg::DrawElementsUInt* pyramidBase = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES,model->indicesNum,model->indices, 0);
> pyramidGeometry->addPrimitiveSet(pyramidBase);
>
>
>
>
> and the shaders
>
> Code:
>
> //vertex shader
>
>
> attribute vec3 a_vertex;
> attribute vec4 a_col;
>
>
> varying vec4 col;
>
> void main() {
> col = a_col;
>
> //gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex
> gl_Position = gl_ModelViewProjectionMatrix * vec4(a_vertex, 1.0);
>
> }
>
> //fragment shader
>
> varying vec4 col;
>
> void main() {
> gl_FragColor =col;
> }