# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1440642304 -10800
# Node ID 1b30bd38166717bf14d132bc00153b6e86adddde
# Parent  4f6168f3ca82f0a07e5a97740490315db51ce6d8
sweep curve mesh gen and dragon horns

diff -r 4f6168f3ca82 -r 1b30bd381667 src/dragon.cc
--- a/src/dragon.cc	Thu Aug 27 01:58:26 2015 +0300
+++ b/src/dragon.cc	Thu Aug 27 05:25:04 2015 +0300
@@ -4,7 +4,9 @@
 #include "metasurf.h"
 #include "geom.h"
 #include "game.h"
+#include "object.h"
 #include "shadow.h"
+#include "meshgen.h"
 
 #define VOXEL_PAD		1.0f
 #define DYN_FCOUNT		64
@@ -19,6 +21,9 @@
 static Vector3 bezier(const Vector3 &a, const Vector3 &b, const Vector3 &c, const Vector3 &d, float t);
 static float mseval(struct metasurface *ms, float x, float y, float z);
 static void msvertex(struct metasurface *ms, float x, float y, float z);
+static void gen_detail_meshes();
+
+static std::vector<Object*> detail_obj;
 
 
 Dragon::Dragon()
@@ -48,6 +53,10 @@
 	msurf_set_threshold(msurf, 1.0);
 	msurf_eval_func(msurf, mseval);
 	msurf_vertex_func(msurf, msvertex);
+
+	if(detail_obj.empty()) {
+		gen_detail_meshes();
+	}
 }
 
 Dragon::~Dragon()
@@ -214,6 +223,17 @@
 		glPopAttrib();
 		if(cur_sdr) glUseProgram(cur_sdr);
 	}
+
+	// draw detail objects
+	for(size_t i=0; i<detail_obj.size(); i++) {
+		detail_obj[i]->xform().set_translation(head_pos);
+
+		if(dbg_wireframe) {
+			detail_obj[i]->draw_wire();
+		} else {
+			detail_obj[i]->draw();
+		}
+	}
 }
 
 void Dragon::flush_dynvbo() const
@@ -290,3 +310,40 @@
 		dragon->flush_dynvbo();
 	}
 }
+
+
+#define HORN_RAD	0.15f
+static Vector2 horn_sweep(float u, float v, void *cls)
+{
+	float t = 1.0f - v;
+	float angle = u * 2.0 * M_PI;
+	float x = sin(angle) * t * HORN_RAD;
+	float y = cos(angle) * t * HORN_RAD;
+	return Vector2(x, y + smoothstep(0.3, 1.0, v) * 0.5);
+}
+
+static void gen_detail_meshes()
+{
+	Mesh *mesh;
+	Object *obj;
+	Matrix4x4 xform;
+
+	for(int i=0; i<2; i++) {
+		float sign = i ? 1.0f : -1.0f;
+
+		mesh = new Mesh;
+		gen_sweep(mesh, 2, 6, 6, horn_sweep, 0);
+		xform.set_translation(Vector3(0.5 * sign, 1.5, 3));
+		xform.rotate(Vector3(DEG_TO_RAD(25), 0, 0));
+		xform.rotate(Vector3(0, 0, DEG_TO_RAD(15) * -sign));
+		mesh->apply_xform(xform, Matrix4x4::identity);
+
+		obj = new Object;
+		obj->set_mesh(mesh);
+		obj->mtl.diffuse = Vector3(1.0, 0.85, 0.8);
+		obj->mtl.specular = Vector3(1, 1, 1);
+		obj->mtl.shininess = 60.0;
+
+		detail_obj.push_back(obj);
+	}
+}
diff -r 4f6168f3ca82 -r 1b30bd381667 src/meshgen.cc
--- a/src/meshgen.cc	Thu Aug 27 01:58:26 2015 +0300
+++ b/src/meshgen.cc	Thu Aug 27 05:25:04 2015 +0300
@@ -689,3 +689,87 @@
 		u += du;
 	}
 }
+
+
+static inline Vector3 sweep_vert(float u, float v, float height, Vector2 (*sf)(float, float, void*), void *cls)
+{
+	Vector2 pos = sf(u, v, cls);
+
+	float x = pos.x;
+	float y = v * height;
+	float z = pos.y;
+
+	return Vector3(x, y, z);
+}
+
+// ---- sweep shape along a path ----
+void gen_sweep(Mesh *mesh, float height, int usub, int vsub, Vector2 (*sfunc)(float, float, void*), void *cls)
+{
+	if(!sfunc) return;
+	if(usub < 3) usub = 3;
+	if(vsub < 1) vsub = 1;
+
+	mesh->clear();
+
+	int uverts = usub + 1;
+	int vverts = vsub + 1;
+	int num_verts = uverts * vverts;
+
+	int num_quads = usub * vsub;
+	int num_tri = num_quads * 2;
+
+	Vector3 *varr = (Vector3*)mesh->set_attrib_data(MESH_ATTR_VERTEX, 3, num_verts, 0);
+	Vector3 *narr = (Vector3*)mesh->set_attrib_data(MESH_ATTR_NORMAL, 3, num_verts, 0);
+	Vector3 *tarr = (Vector3*)mesh->set_attrib_data(MESH_ATTR_TANGENT, 3, num_verts, 0);
+	Vector2 *uvarr = (Vector2*)mesh->set_attrib_data(MESH_ATTR_TEXCOORD, 2, num_verts, 0);
+	unsigned int *idxarr = mesh->set_index_data(num_tri * 3, 0);
+
+	float du = 1.0 / (float)(uverts - 1);
+	float dv = 1.0 / (float)(vverts - 1);
+
+	float u = 0.0;
+	for(int i=0; i<uverts; i++) {
+		float v = 0.0;
+		for(int j=0; j<vverts; j++) {
+			Vector3 pos = sweep_vert(u, v, height, sfunc, cls);
+
+			Vector3 nextu = sweep_vert(fmod(u + du, 1.0), v, height, sfunc, cls);
+			Vector3 tang = nextu - pos;
+			if(tang.length_sq() < 1e-6) {
+				float new_v = v > 0.5 ? v - dv * 0.25 : v + dv * 0.25;
+				nextu = sweep_vert(fmod(u + du, 1.0), new_v, height, sfunc, cls);
+				tang = nextu - pos;
+			}
+
+			Vector3 normal;
+			Vector3 nextv = sweep_vert(u, v + dv, height, sfunc, cls);
+			Vector3 bitan = nextv - pos;
+			if(bitan.length_sq() < 1e-6) {
+				nextv = sweep_vert(u, v - dv, height, sfunc, cls);
+				bitan = pos - nextv;
+			}
+
+			normal = cross_product(tang, bitan);
+
+			*varr++ = pos;
+			*narr++ = normal.normalized();
+			*tarr++ = tang.normalized();
+			*uvarr++ = Vector2(u, v);
+
+			if(i < usub && j < vsub) {
+				int idx = i * vverts + j;
+
+				*idxarr++ = idx;
+				*idxarr++ = idx + vverts + 1;
+				*idxarr++ = idx + 1;
+
+				*idxarr++ = idx;
+				*idxarr++ = idx + vverts;
+				*idxarr++ = idx + vverts + 1;
+			}
+
+			v += dv;
+		}
+		u += du;
+	}
+}
diff -r 4f6168f3ca82 -r 1b30bd381667 src/meshgen.h
--- a/src/meshgen.h	Thu Aug 27 01:58:26 2015 +0300
+++ b/src/meshgen.h	Thu Aug 27 05:25:04 2015 +0300
@@ -16,4 +16,7 @@
 void gen_revol(Mesh *mesh, int usub, int vsub, Vector2 (*rfunc)(float, float, void*), void *cls = 0);
 void gen_revol(Mesh *mesh, int usub, int vsub, Vector2 (*rfunc)(float, float, void*), Vector2 (*nfunc)(float, float, void*), void *cls);
 
+/* callback args: (float u, float v, void *cls) -> Vector2 XZ offset u,v in [0, 1] */
+void gen_sweep(Mesh *mesh, float height, int usub, int vsub, Vector2 (*sfunc)(float, float, void*), void *cls = 0);
+
 #endif	// MESHGEN_H_