From 2bc4bcebc93e7211dfb84303888635f888ba8018 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 20 Feb 2021 00:17:58 +0000
Subject: Custom land and water shaders

Create sandy beaches, snow topped mountains and grassy hills with a single texture, coloured
according to land height by a custom shader.
Also use the land mass mesh with a new water texture and a custom shader to create rather nice
looking water effect with depth, waves and motion.
---
 gfx/gl/shaders/landmassShader.fs | 41 ++++++++++++++++++++++++++++++++++++++++
 gfx/gl/shaders/landmassShader.vs | 21 ++++++++++++++++++++
 gfx/gl/shaders/waterShader.fs    | 13 +++++++++++++
 gfx/gl/shaders/waterShader.vs    | 23 ++++++++++++++++++++++
 4 files changed, 98 insertions(+)
 create mode 100644 gfx/gl/shaders/landmassShader.fs
 create mode 100644 gfx/gl/shaders/landmassShader.vs
 create mode 100644 gfx/gl/shaders/waterShader.fs
 create mode 100644 gfx/gl/shaders/waterShader.vs

(limited to 'gfx/gl/shaders')

diff --git a/gfx/gl/shaders/landmassShader.fs b/gfx/gl/shaders/landmassShader.fs
new file mode 100644
index 0000000..36cc971
--- /dev/null
+++ b/gfx/gl/shaders/landmassShader.fs
@@ -0,0 +1,41 @@
+#version 130
+
+in vec2 texCoord0;
+in vec3 normal0;
+in float height;
+
+uniform sampler2D sampler;
+uniform vec3 lightDirection;
+uniform vec3 lightColor;
+uniform vec3 ambientColor;
+
+const vec3 grass = vec3(.1, .4, .05);
+const vec3 sand = vec3(.76, .7, .5);
+const vec3 snow = vec3(.97, .97, .99);
+
+vec2
+grad_between(float x, float lower, float upper)
+{
+	float off = (x - lower) / (upper - lower);
+	return vec2(off, 1 - off);
+}
+
+void
+main()
+{
+	gl_FragColor = texture(sampler, texCoord0);
+	gl_FragColor.xyz *= clamp(ambientColor + (dot(-lightDirection, normal0) * lightColor), 0.0, 1.0);
+	if (height < 0.5) {
+		gl_FragColor.rgb *= sand;
+	}
+	else if (height > 30) {
+		gl_FragColor.rgb *= snow;
+	}
+	else if (height > 28) {
+		vec2 grad = grad_between(height, 28, 30);
+		gl_FragColor.rgb *= grass + (snow - grass) * grad.x;
+	}
+	else {
+		gl_FragColor.rgb *= grass;
+	}
+}
diff --git a/gfx/gl/shaders/landmassShader.vs b/gfx/gl/shaders/landmassShader.vs
new file mode 100644
index 0000000..72c9060
--- /dev/null
+++ b/gfx/gl/shaders/landmassShader.vs
@@ -0,0 +1,21 @@
+#version 130
+
+in vec3 position;
+in vec2 texCoord;
+in vec3 normal;
+
+out vec2 texCoord0;
+out vec3 normal0;
+out float height;
+
+uniform mat4 viewProjection;
+uniform mat4 model;
+uniform vec3 waves;
+
+void main()
+{
+	gl_Position = viewProjection * model * vec4(position, 1.0);
+	texCoord0 = texCoord;
+	normal0 = normal;
+	height = position.y;
+}
diff --git a/gfx/gl/shaders/waterShader.fs b/gfx/gl/shaders/waterShader.fs
new file mode 100644
index 0000000..bdfbc33
--- /dev/null
+++ b/gfx/gl/shaders/waterShader.fs
@@ -0,0 +1,13 @@
+#version 130
+
+in vec2 texCoord0;
+in float depth;
+
+uniform sampler2D sampler;
+uniform vec3 waves;
+
+void main()
+{
+	gl_FragColor = texture(sampler, texCoord0);
+	gl_FragColor.a *= clamp(-depth * .7, .1, 1.0);
+}
diff --git a/gfx/gl/shaders/waterShader.vs b/gfx/gl/shaders/waterShader.vs
new file mode 100644
index 0000000..55a0fb8
--- /dev/null
+++ b/gfx/gl/shaders/waterShader.vs
@@ -0,0 +1,23 @@
+#version 130
+
+in vec3 position;
+in vec2 texCoord;
+in vec3 normal;
+
+out vec2 texCoord0;
+out float depth;
+
+uniform mat4 viewProjection;
+uniform mat4 model;
+uniform vec3 waves;
+
+void main()
+{
+	vec3 wpos = vec3(
+			position.x + cos(waves.x),
+			cos(waves.x + position.x + (position.z / 7)) * .3,
+			position.z + cos(waves.x * waves.z));
+	gl_Position = viewProjection * model * vec4(wpos, 1.0);
+	texCoord0 = texCoord;
+	depth = position.y;
+}
-- 
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