From f53283be1251e0e14dd5d0ab34d9dd7140ebe8bc Mon Sep 17 00:00:00 2001
From: Stuart Buchanan <stuart_d_buchanan@yahoo.co.uk>
Date: Sat, 6 Nov 2021 15:29:22 +0000
Subject: [PATCH] WS30: Correct orthophoto texture coordinates

---
 Shaders/ws30-photo.frag | 68 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 Shaders/ws30-photo.frag

diff --git a/Shaders/ws30-photo.frag b/Shaders/ws30-photo.frag
new file mode 100644
index 000000000..a707c362c
--- /dev/null
+++ b/Shaders/ws30-photo.frag
@@ -0,0 +1,68 @@
+// -*-C++-*-
+
+// Ambient term comes in gl_Color.rgb.
+#version 120
+
+varying vec4 diffuse_term;
+varying vec3 normal;
+varying vec2 orthoTexCoord;
+varying vec4 ecPosition;
+
+uniform sampler2D texture;
+
+////fog "include" /////
+uniform int fogType;
+
+uniform bool orthophotoAvailable;
+
+vec3 fog_Func(vec3 color, int type);
+//////////////////////
+
+float getShadowing();
+vec3 getClusteredLightsContribution(vec3 p, vec3 n, vec3 texel);
+
+float luminance(vec3 color)
+{
+    return dot(vec3(0.212671, 0.715160, 0.072169), color);
+}
+
+void main()
+{
+    vec3 n;
+    float NdotL, NdotHV, fogFactor;
+    vec4 color = gl_Color;
+    vec3 lightDir = gl_LightSource[0].position.xyz;
+    vec3 halfVector = gl_LightSource[0].halfVector.xyz;
+    vec4 texel;
+    vec4 fragColor;
+    vec4 specular = vec4(0.0);
+
+    // If gl_Color.a == 0, this is a back-facing polygon and the
+    // normal should be reversed.
+    n = (2.0 * gl_Color.a - 1.0) * normal;
+    n = normalize(n);
+
+    NdotL = dot(n, lightDir);
+    if (NdotL > 0.0) {
+        float shadowmap = getShadowing();
+        color += diffuse_term * NdotL * shadowmap;
+        NdotHV = max(dot(n, halfVector), 0.0);
+        if (gl_FrontMaterial.shininess > 0.0)
+            specular.rgb = (gl_FrontMaterial.specular.rgb
+                            * gl_LightSource[0].specular.rgb
+                            * pow(NdotHV, gl_FrontMaterial.shininess)
+                            * shadowmap);
+    }
+    color.a = diffuse_term.a;
+    // This shouldn't be necessary, but our lighting becomes very
+    // saturated. Clamping the color before modulating by the texture
+    // is closer to what the OpenGL fixed function pipeline does.
+    color = clamp(color, 0.0, 1.0);
+    texel = texture2D(texture, vec2(gl_TexCoord[0].s, 1.0 - gl_TexCoord[0].t));
+
+    fragColor = color * texel + specular;
+    fragColor.rgb += getClusteredLightsContribution(ecPosition.xyz, n, texel.rgb);
+
+    fragColor.rgb = fog_Func(fragColor.rgb, fogType);
+    gl_FragColor = fragColor;
+}