From d1d1a4e349f18cd36406f75170dad87fbad2722a Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 20 Jan 2024 13:00:49 +0000
Subject: Common code between straight/curve network geometry shaders

---
 gfx/gl/shaders/networkCommon.glsl | 41 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 gfx/gl/shaders/networkCommon.glsl

(limited to 'gfx/gl/shaders/networkCommon.glsl')

diff --git a/gfx/gl/shaders/networkCommon.glsl b/gfx/gl/shaders/networkCommon.glsl
new file mode 100644
index 0000000..2639eb1
--- /dev/null
+++ b/gfx/gl/shaders/networkCommon.glsl
@@ -0,0 +1,41 @@
+const float RAIL_HEIGHT = 250;
+const vec3[] profile = vec3[]( //
+		vec3(-1900.F, 0.F, 0.F), //
+		vec3(-608.F, 0.F, RAIL_HEIGHT), //
+		vec3(0, 0.F, RAIL_HEIGHT * .7F), //
+		vec3(608.F, 0.F, RAIL_HEIGHT), //
+		vec3(1900.F, 0.F, 0.F));
+const float[profile.length()] texturePos = float[](0, 0.34, 0.5, 0.65, 1);
+
+uniform mat4 viewProjection;
+uniform ivec3 viewPoint;
+
+uniform float clipDistance = 5000000;
+uniform float flatDistance = 1000000;
+
+out vec2 texCoord;
+out vec3 rposition;
+
+void
+doVertex(const ivec3 end, const int v, const float texY, const mat2 rot)
+{
+	rposition = vec3(rot * profile[v].xy, profile[v].z);
+	ivec3 vpos = end + ivec3(rposition);
+	gl_Position = viewProjection * vec4(vpos - viewPoint, 1);
+	texCoord = vec2(texturePos[v], texY);
+	EmitVertex();
+}
+
+void
+doSeg(const float dist, const ivec3 apos, const ivec3 bpos, const float atexY, const float btexY, const mat2 arot,
+		const mat2 brot)
+{
+	if (dist < clipDistance) {
+		int vstep = (dist < flatDistance) ? 1 : profile.length() - 1;
+		for (int v = 0; v < profile.length(); v += vstep) {
+			doVertex(bpos, v, btexY, brot);
+			doVertex(apos, v, atexY, arot);
+		}
+		EndPrimitive();
+	}
+}
-- 
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