All polygons are rendered with same objectID after installing custom shader #2813
Description
osgEarth Version : 3.7.2
Description of the problem: Not able to handle polygon rendering from custom shader.
Added a custom shader for updating the color of a feature after selection.
Below is the code for the custom shader. However, after installing the custom shader, the selection of polygon features stops working. Upon investigation, it was found that the objectID for all polygon features becomes the same after installing the shader.
const char* highlight_shader = R"(
#pragma vp_function check_for_highlight, vertex_clip
uniform uint selectedFeatCount;
uniform uint selectionIds[500];
uint oe_index_objectid; // Stage global containing object id
flat out int selected;
void check_for_highlight(inout vec4 vertex)
{
selected =0;
for(int i = 0; i < selectedFeatCount; i++)
{
uint val = selectionIds[i];
if(val == oe_index_objectid)
{
selected = 1;
break;
}
}
}
[break]
#pragma vp_function highlight_fragment, fragment
flat in int selected;
void highlight_fragment(inout vec4 color)
{
if ( selected == 1 )
{
color = vec4(1.0, 0.0, 1.0, 1.0); // magenta highlight
}
}
)";
void Osg::CGShader::Initialize()
{
int attrLocation = Registry::objectIndex()->getObjectIDAttribLocation();
// This shader program will highlight the selected object.
VirtualProgram* vp = VirtualProgram::getOrCreate(stateSet);
auto res = ShaderLoader::load(vp, this->shaderSource);
// Since we're accessing object IDs, we need to load the indexing shader as well:
res = Registry::objectIndex()->loadShaders(vp);
}