From 535be42da6a32cae03fd0422b44862fdf9638c5b Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 25 Jan 2021 01:11:09 +0000
Subject: Generate some basic flat terrain

---
 game/terrain.cpp | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 game/terrain.cpp

(limited to 'game/terrain.cpp')

diff --git a/game/terrain.cpp b/game/terrain.cpp
new file mode 100644
index 0000000..1669a62
--- /dev/null
+++ b/game/terrain.cpp
@@ -0,0 +1,87 @@
+#include "terrain.h"
+#include "gfx/models/texture.h"
+#include <array>
+#include <cache.h>
+#include <cstddef>
+#include <gfx/gl/shader.h>
+#include <gfx/gl/transform.h>
+#include <gfx/models/vertex.hpp>
+#include <glm/glm.hpp>
+
+constexpr auto size {255}; // Vertices
+constexpr auto verticesCount = size * size;
+constexpr auto tilesCount = (size - 1) * (size - 1);
+constexpr auto trianglesCount = tilesCount * 2;
+constexpr auto indicesCount = trianglesCount * 3;
+constexpr auto resolution = 10; // Grid size
+
+Terrain::Terrain() :
+	m_vertexArrayObject {}, m_vertexArrayBuffers {}, texture {Texture::cachedTexture.get("res/bricks.jpg")}
+{
+	vertices.resize(verticesCount, {{}, {}, {}});
+	indices.reserve(indicesCount);
+
+	// Initial coordinates
+	for (auto z = 0; z < size; z += 1) {
+		for (auto x = 0; x < size; x += 1) {
+			auto & vertex = vertices[x + (z * size)];
+			vertex.pos = {resolution * x, -1, resolution * z};
+			vertex.normal = {0, 1, 0};
+			vertex.texCoord = {x % 2, z % 2};
+		}
+	}
+	// Indices
+	for (auto z = 0; z < size - 1; z += 1) {
+		for (auto x = 0; x < size - 1; x += 1) {
+			indices.push_back(x + (z * size));
+			indices.push_back((x + 1) + ((z + 1) * size));
+			indices.push_back((x + 1) + (z * size));
+			indices.push_back(x + (z * size));
+			indices.push_back(x + ((z + 1) * size));
+			indices.push_back((x + 1) + ((z + 1) * size));
+		}
+	}
+
+	glGenVertexArrays(1, &m_vertexArrayObject);
+	glBindVertexArray(m_vertexArrayObject);
+
+	glGenBuffers(2, m_vertexArrayBuffers.data());
+
+	glBindBuffer(GL_ARRAY_BUFFER, m_vertexArrayBuffers[0]);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * verticesCount, vertices.data(), GL_STATIC_DRAW);
+
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, pos));
+
+	glEnableVertexAttribArray(1);
+	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, texCoord));
+
+	glEnableVertexAttribArray(2);
+	glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, normal));
+
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_vertexArrayBuffers[1]);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices[0]) * indicesCount, indices.data(), GL_STATIC_DRAW);
+
+	glBindVertexArray(0);
+}
+
+Terrain::~Terrain()
+{
+	glDeleteBuffers(NUM_BUFFERS, m_vertexArrayBuffers.data());
+	glDeleteVertexArrays(1, &m_vertexArrayObject);
+}
+
+static const Transform identity {};
+static const auto identityModel {identity.GetModel()};
+
+void
+Terrain::render(const Shader & shader) const
+{
+	shader.setModel(identityModel);
+	texture->Bind();
+	glBindVertexArray(m_vertexArrayObject);
+
+	glDrawElementsBaseVertex(GL_TRIANGLES, indicesCount, GL_UNSIGNED_INT, nullptr, 0);
+
+	glBindVertexArray(0);
+}
-- 
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