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.
---
 game/terrain.cpp | 44 +++++++++++++-------------------------------
 game/terrain.h   |  4 ++--
 2 files changed, 15 insertions(+), 33 deletions(-)

(limited to 'game')

diff --git a/game/terrain.cpp b/game/terrain.cpp
index 83116fc..20c06e8 100644
--- a/game/terrain.cpp
+++ b/game/terrain.cpp
@@ -9,13 +9,10 @@
 #include <gfx/models/mesh.h>
 #include <gfx/models/vertex.hpp>
 #include <glm/glm.hpp>
+#include <maths.h>
 #include <random>
 #include <stb_image.h>
 
-template<unsigned int Comp> class TerrainComp : public Mesh {
-	using Mesh::Mesh;
-};
-
 Terrain::Terrain() : grass {Texture::cachedTexture.get("grass.png")}, water {Texture::cachedTexture.get("water.png")}
 {
 	constexpr auto size {241}; // Vertices
@@ -66,7 +63,6 @@ Terrain::Terrain() : grass {Texture::cachedTexture.get("grass.png")}, water {Tex
 		}
 	}
 	finish(size, size, vertices);
-	addWater(size, size, resolution);
 }
 
 Terrain::Terrain(const std::string & fileName) :
@@ -89,7 +85,6 @@ Terrain::Terrain(const std::string & fileName) :
 	}
 
 	finish(map.width, map.height, vertices);
-	addWater(map.width, map.height, resolution);
 }
 
 void
@@ -125,40 +120,27 @@ Terrain::finish(unsigned int width, unsigned int height, std::vector<Vertex> & v
 			v(width, x, z).normal = -glm::normalize(glm::cross(c - a, d - b));
 		}
 	}
-	meshes.create<TerrainComp<0>>(vertices, indices);
+	meshes.create<Mesh>(vertices, indices);
 }
 
+static const Transform identity {};
+static const auto identityModel {identity.GetModel()};
+
 void
-Terrain::addWater(unsigned int width, unsigned int height, unsigned int resolution)
+Terrain::tick(TickDuration dur)
 {
-	const auto verticesCount {0U};
-	std::vector<Vertex> vertices;
-	std::vector<unsigned int> indices;
-	// Add water
-	const auto extentx {(int)((width - 1) * resolution / 2)};
-	const auto extentz {(int)((height - 1) * resolution / 2)};
-	vertices.emplace_back(glm::vec3 {-extentx, 0, -extentz}, glm::vec2 {0, 0}, glm::vec3 {0, 1, 0});
-	vertices.emplace_back(glm::vec3 {-extentx, 0, extentz}, glm::vec2 {0, height}, glm::vec3 {0, 1, 0});
-	vertices.emplace_back(glm::vec3 {extentx, 0, extentz}, glm::vec2 {width, height}, glm::vec3 {0, 1, 0});
-	vertices.emplace_back(glm::vec3 {extentx, 0, -extentz}, glm::vec2 {width, 0}, glm::vec3 {0, 1, 0});
-	indices.push_back(verticesCount);
-	indices.push_back(verticesCount + 1);
-	indices.push_back(verticesCount + 2);
-	indices.push_back(verticesCount);
-	indices.push_back(verticesCount + 2);
-	indices.push_back(verticesCount + 3);
-	meshes.create<TerrainComp<1>>(vertices, indices);
+	waveCycle += dur.count();
 }
 
-static const Transform identity {};
-static const auto identityModel {identity.GetModel()};
-
 void
 Terrain::render(const Shader & shader) const
 {
-	shader.setModel(identityModel);
+	shader.setModel(identityModel, Shader::Program::LandMass);
 	grass->Bind();
-	meshes.apply<TerrainComp<0>>(&Mesh::Draw);
+	meshes.apply(&Mesh::Draw);
+
+	shader.setModel(identityModel, Shader::Program::Water);
+	shader.setUniform("waves", {waveCycle, 0, 0});
 	water->Bind();
-	meshes.apply<TerrainComp<1>>(&Mesh::Draw);
+	meshes.apply(&Mesh::Draw);
 }
diff --git a/game/terrain.h b/game/terrain.h
index 1aed1c5..2cec963 100644
--- a/game/terrain.h
+++ b/game/terrain.h
@@ -20,13 +20,13 @@ public:
 
 	void render(const Shader & shader) const override;
 
-	void tick(TickDuration) override { }
+	void tick(TickDuration) override;
+	float waveCycle {0.F};
 
 private:
 	static constexpr unsigned int NUM_BUFFERS {4};
 
 	void finish(unsigned int width, unsigned int height, std::vector<Vertex> &);
-	void addWater(unsigned int width, unsigned int height, unsigned int resolution);
 
 	Collection<Mesh, false> meshes;
 	std::shared_ptr<Texture> grass, water;
-- 
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