From 2b4b3f95cae61b8260970dd58732a39673217b43 Mon Sep 17 00:00:00 2001
From: Joursoir <chat@joursoir.net>
Date: Mon, 29 Mar 2021 17:23:07 +0000
Subject: add object forming

---
 src/objects.cpp | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/objects.hpp |   9 +++++
 2 files changed, 132 insertions(+)
 create mode 100644 src/objects.cpp
 create mode 100644 src/objects.hpp

diff --git a/src/objects.cpp b/src/objects.cpp
new file mode 100644
index 0000000..4400a2d
--- /dev/null
+++ b/src/objects.cpp
@@ -0,0 +1,123 @@
+#include <glm/glm.hpp>
+
+#include "objects.hpp"
+#include "graphics/Mesh.hpp"
+#include "graphics/Vertex.hpp"
+
+#define PI 3.1415926535
+
+using namespace glm;
+
+const int cube_num_v = 8;
+Vertex cube_vertices[cube_num_v] = {
+	// first 4 - up edge
+	{ vec3(-0.5f, -0.5f, -0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(0.5f, -0.5f, -0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(0.5f, 0.5f, -0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(-0.5f, 0.5f, -0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(0.5f, 0.5f, 0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(-0.5f, 0.5f, 0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(-0.5f, -0.5f, 0.5f), vec2(0.0f, 0.0f) },
+	{ vec3(0.5f, -0.5f, 0.5f), vec2(0.0f, 0.0f) }
+};
+
+const int cube_num_i = 12 * 3;
+GLuint cube_indices[cube_num_i] = {
+	0, 1, 2, // up edge
+ 	0, 2, 3,
+	2, 3, 4, // far edge
+	3, 4, 5,
+	0, 3, 5, // left edge
+	0, 5, 6,
+	0, 6, 7, // near edge
+	0, 1, 7,
+	1, 4, 7, // right edge
+	1, 2, 4,
+	4, 5, 7, // down edge
+	4, 6, 7
+};
+
+Mesh *form_cube()
+{
+	return new Mesh(cube_vertices, cube_num_v, cube_indices, cube_num_i);
+}
+
+Mesh *form_sphere(int longitude_count, int latitude_count)
+{
+	/* The points on the sphere with radius r > 0 and center (x0, y0, z0)...
+		...can be parameterized via:
+	{
+		x = x0 + R * sin(tetta) * cos(phi)
+		y = y0 + R * sin(tetta) * sin(phi)
+		z = z0 + R * cos(tetta)
+		tetta : [0, PI];  phi : [0, 2PI]
+	}
+	or:
+	{
+		x = x0 + R * cos(phi) * cos(tetta)
+		y = y0 + R * cos(phi) * sin(tetta)
+		z = z0 + R * sin(phi)
+	}
+	our x0, y0, z0 = 0 */
+	int i, j, idx, k1, k2;
+	float x, y, z;
+	float s, t;
+	float radius = 1.0;
+
+	// sectors
+	float longitude_step = PI / longitude_count;
+	float longitude_angle;
+
+	// stacks
+	float latitude_step = 2 * PI / latitude_count;
+	float latitude_angle;
+
+	int sphere_num_v = (longitude_count + 1) * (latitude_count + 1);
+	Vertex *sphere_vertices = new Vertex[sphere_num_v];
+	for(i = 0, idx = 0; i <= longitude_count; i++) {
+		longitude_angle = i * longitude_step;
+		z = radius * cos(longitude_angle);
+
+		for(j = 0; j <= latitude_count; j++) {
+			latitude_angle = j * latitude_step;
+
+			x = radius * sinf(longitude_angle) * cosf(latitude_angle);
+			y = radius * sinf(longitude_angle) * sinf(latitude_angle);
+			sphere_vertices[idx].pos_coords = glm::vec3(x, y, z);
+
+			s = (float)j / longitude_count;
+			t = (float)i / latitude_count;
+			sphere_vertices[idx].tex_coords = glm::vec2(s, t);
+			idx++;
+		}
+	}
+
+	int sphere_num_i = (longitude_count - 1) * latitude_count * 6;
+	GLuint *sphere_indices = new GLuint[sphere_num_i];
+	for(i = 0, idx = 0; i < longitude_count; i++) {
+		k1 = i * (latitude_count+1);
+		k2 = k1 + (latitude_count+1);
+
+		for(j = 0; j < latitude_count; j++, k1++, k2++) {
+			if(i != 0)
+			{
+				sphere_indices[idx++] = k1;
+				sphere_indices[idx++] = k2;
+				sphere_indices[idx++] = k1 + 1;
+			}
+			if(i != (longitude_count-1))
+			{
+				sphere_indices[idx++] = k1 + 1;
+				sphere_indices[idx++] = k2;
+				sphere_indices[idx++] = k2 + 1;
+			}
+		}
+	}
+
+	Mesh *sphere = new Mesh(sphere_vertices, sphere_num_v,
+		sphere_indices, sphere_num_i);
+
+	delete[] sphere_vertices;
+	delete[] sphere_indices;
+	return sphere;
+}
diff --git a/src/objects.hpp b/src/objects.hpp
new file mode 100644
index 0000000..74ba884
--- /dev/null
+++ b/src/objects.hpp
@@ -0,0 +1,9 @@
+#ifndef ENGINE_OBJECTS_H
+#define ENGINE_OBJECTS_H
+
+class Mesh;
+
+Mesh *form_cube();
+Mesh *form_sphere(int longitude_count, int latitude_count);
+
+#endif /* ENGINE_OBJECTS_H */
-- 
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