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uniform vec2 Viewport;
layout(points) in;
layout(triangle_strip, max_vertices = 4) out;
in vec4 finalColor[1];
in float finalThickness[1];
out vec4 mColor;
out vec2 mTexCoord;
/* project 3d point to 2d on screen space */
vec2 toScreenSpace(vec4 vertex)
{
return vec2(vertex.xy / vertex.w) * Viewport;
}
/* get zdepth value */
float getZdepth(vec4 point)
{
return min(-0.05, (point.z / point.w));
}
void main(void)
{
vec4 P0 = gl_in[0].gl_Position;
vec2 sp0 = toScreenSpace(P0);
float size = finalThickness[0];
/* generate the triangle strip */
mTexCoord = vec2(0, 1);
mColor = finalColor[0];
gl_Position = vec4(vec2(sp0.x - size, sp0.y + size) / Viewport, getZdepth(P0), 1.0);
EmitVertex();
mTexCoord = vec2(0, 0);
mColor = finalColor[0];
gl_Position = vec4(vec2(sp0.x - size, sp0.y - size) / Viewport, getZdepth(P0), 1.0);
EmitVertex();
mTexCoord = vec2(1, 1);
mColor = finalColor[0];
gl_Position = vec4(vec2(sp0.x + size, sp0.y + size) / Viewport, getZdepth(P0), 1.0);
EmitVertex();
mTexCoord = vec2(1, 0);
mColor = finalColor[0];
gl_Position = vec4(vec2(sp0.x + size, sp0.y - size) / Viewport, getZdepth(P0), 1.0);
EmitVertex();
EndPrimitive();
}
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