Add rendering support for point lights

1 files changed, 44 insertions, 0 deletions

diff --git a/gfx/gl/shaders/pointLight.gs b/gfx/gl/shaders/pointLight.gs
new file mode 100644
index 0000000..2bd71e9
--- /dev/null
+++ b/gfx/gl/shaders/pointLight.gs
@@ -0,0 +1,44 @@
+#version 330 core
+#extension GL_ARB_enhanced_layouts : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+const int maxv = 128;
+const int maxarcs = (maxv / 2) - 1;
+const int minarcs = 10;
+const float tau = radians(360);
+const float scale = 150;
+uniform ivec4 viewPort;
+
+in vec3 centre[];
+in float size[];
+layout(points) in;
+
+layout(triangle_strip, max_vertices = maxv) out;
+out vec3 geo_centre;
+
+void
+doSeg(float arc, vec2 radius)
+{
+	gl_Position = gl_in[0].gl_Position;
+	geo_centre = centre[0];
+	EmitVertex();
+
+	const vec2 off = vec2(cos(arc), sin(arc)) * radius;
+	gl_Position.xy = gl_in[0].gl_Position.xy + off;
+	geo_centre = centre[0];
+	EmitVertex();
+}
+
+void
+main()
+{
+	const vec2 display = viewPort.zw;
+	const vec2 ratio = vec2(1, display.x / display.y);
+	const vec2 radius = (size[0] * ratio * scale) / gl_in[0].gl_Position.w;
+	const float step = tau / clamp(radius.x, minarcs, maxarcs);
+	for (float arc = 0; arc < tau; arc += step) {
+		doSeg(arc, radius);
+	}
+	doSeg(tau, radius);
+	EndPrimitive();
+}