Hi, I have a problem with the following geometry shader. It outputs nothing. If I replace “triangle_strip” with “line_strip”, it works just fine. What am I missing? Thank you.

```
[Vertex Shader]
#version 330
layout(location=0) in vec2 position;
void main()
{
gl_Position=vec4(position.x,0.0,position.y,1.0);
}
[Geometry Shader]
#version 330
layout(points) in;
layout(triangle_strip,max_vertices=6) out;
uniform mat4 proj;
uniform mat4 view;
uniform mat4 model;
uniform float hsize;
void make_tri(in mat4 mvp, in vec3 p1, in vec3 p2, in vec3 p3)
{
gl_Position=mvp*vec4(p1,1.0);
EmitVertex();
gl_Position=mvp*vec4(p2,1.0);
EmitVertex();
gl_Position=mvp*vec4(p3,1.0);
EmitVertex();
EndPrimitive();
}
void main()
{
mat4 mv=view*model;
mat4 mvp=proj*mv;
vec3 p1=vec3(gl_in[0].gl_Position.x-hsize,0.0,gl_in[0].gl_Position.z+hsize);
vec3 p2=vec3(gl_in[0].gl_Position.x-hsize,0.0,gl_in[0].gl_Position.z-hsize);
vec3 p3=vec3(gl_in[0].gl_Position.x+hsize,0.0,gl_in[0].gl_Position.z-hsize);
vec3 p4=vec3(gl_in[0].gl_Position.x+hsize,0.0,gl_in[0].gl_Position.z+hsize);
make_tri(mvp,p1,p2,p3);
make_tri(mvp,p3,p4,p1);
}
[Fragment Shader]
#version 330
out vec4 outcol;
void main()
{
outcol=vec4(1.0);
}
```