// ----------------------------------------------------------------------------
// Simple sample to prove that Assimp is easy to use with OpenGL.
// It takes a file name as command line parameter, loads it using standard
// settings and displays it.
//
// If you intend to _use_ this code sample in your app, do yourself a favour 
// and replace immediate mode calls with VBOs ...
//
// The vc8 solution links against assimp-release-dll_win32 - be sure to
// have this configuration built.
// ----------------------------------------------------------------------------

#include "GL/glut.h"

// assimp include files. These three are usually needed.
#include "assimp.h"
#include "aiPostProcess.h"
#include "aiScene.h"

// the global Assimp scene object
const struct aiScene* scene = NULL;
GLuint scene_list = 0;
struct aiVector3D scene_min, scene_max, scene_center;

// current rotation angle
static float angle = 0.f;

#define aisgl_min(x,y) (x<y?x:y)
#define aisgl_max(x,y) (y>x?y:x)

// ----------------------------------------------------------------------------
void reshape(int width, int height)
{
	const double aspectRatio = (float) width / height, fieldOfView = 45.0;

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(fieldOfView, aspectRatio,
		1.0, 1000.0);  /* Znear and Zfar */
	glViewport(0, 0, width, height);
}

// ----------------------------------------------------------------------------
void get_bounding_box_for_node (const struct aiNode* nd, 
	struct aiVector3D* min, 
	struct aiVector3D* max, 
	struct aiMatrix4x4* trafo
){
	struct aiMatrix4x4 prev;
	unsigned int n = 0, t;

	prev = *trafo;
	aiMultiplyMatrix4(trafo,&nd->mTransformation);

	for (; n < nd->mNumMeshes; ++n) {
		const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]];
		for (t = 0; t < mesh->mNumVertices; ++t) {

			struct aiVector3D tmp = mesh->mVertices[t];
			aiTransformVecByMatrix4(&tmp,trafo);

			min->x = aisgl_min(min->x,tmp.x);
			min->y = aisgl_min(min->y,tmp.y);
			min->z = aisgl_min(min->z,tmp.z);

			max->x = aisgl_max(max->x,tmp.x);
			max->y = aisgl_max(max->y,tmp.y);
			max->z = aisgl_max(max->z,tmp.z);
		}
	}

	for (n = 0; n < nd->mNumChildren; ++n) {
		get_bounding_box_for_node(nd->mChildren[n],min,max,trafo);
	}
	*trafo = prev;
}

// ----------------------------------------------------------------------------

void get_bounding_box (struct aiVector3D* min, struct aiVector3D* max)
{
	struct aiMatrix4x4 trafo;
	aiIdentityMatrix4(&trafo);

	min->x = min->y = min->z =  1e10f;
	max->x = max->y = max->z = -1e10f;
	get_bounding_box_for_node(scene->mRootNode,min,max,&trafo);
}

// ----------------------------------------------------------------------------

void color4_to_float4(const struct aiColor4D *c, float f[4])
{
	f[0] = c->r;
	f[1] = c->g;
	f[2] = c->b;
	f[3] = c->a;
}

// ----------------------------------------------------------------------------

void set_float4(float f[4], float a, float b, float c, float d)
{
	f[0] = a;
	f[1] = b;
	f[2] = c;
	f[3] = d;
}

// ----------------------------------------------------------------------------
void apply_material(const struct aiMaterial *mtl)
{
	float c[4];

	GLenum fill_mode;
	int ret1, ret2;
	struct aiColor4D diffuse;
	struct aiColor4D specular;
	struct aiColor4D ambient;
	struct aiColor4D emission;
	float shininess, strength;
	int two_sided;
	int wireframe;
	int max;

	set_float4(c, 0.8f, 0.8f, 0.8f, 1.0f);
	if(AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_DIFFUSE, &diffuse))
		color4_to_float4(&diffuse, c);
	glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, c);

	set_float4(c, 0.0f, 0.0f, 0.0f, 1.0f);
	if(AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_SPECULAR, &specular))
		color4_to_float4(&specular, c);
	glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, c);

	set_float4(c, 0.2f, 0.2f, 0.2f, 1.0f);
	if(AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_AMBIENT, &ambient))
		color4_to_float4(&ambient, c);
	glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, c);

	set_float4(c, 0.0f, 0.0f, 0.0f, 1.0f);
	if(AI_SUCCESS == aiGetMaterialColor(mtl, AI_MATKEY_COLOR_EMISSIVE, &emission))
		color4_to_float4(&emission, c);
	glMaterialfv(GL_FRONT_AND_BACK, GL_EMISSION, c);

	max = 1;
	ret1 = aiGetMaterialFloatArray(mtl, AI_MATKEY_SHININESS, &shininess, &max);
	max = 1;
	ret2 = aiGetMaterialFloatArray(mtl, AI_MATKEY_SHININESS_STRENGTH, &strength, &max);
	if((ret1 == AI_SUCCESS) && (ret2 == AI_SUCCESS))
		glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, shininess * strength);
	else {
		glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 0.0f);
		set_float4(c, 0.0f, 0.0f, 0.0f, 0.0f);
		glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, c);
	}

	max = 1;
	if(AI_SUCCESS == aiGetMaterialIntegerArray(mtl, AI_MATKEY_ENABLE_WIREFRAME, &wireframe, &max))
		fill_mode = wireframe ? GL_LINE : GL_FILL;
	else
		fill_mode = GL_FILL;
	glPolygonMode(GL_FRONT_AND_BACK, fill_mode);

	max = 1;
	if((AI_SUCCESS == aiGetMaterialIntegerArray(mtl, AI_MATKEY_TWOSIDED, &two_sided, &max)) && two_sided)
		glEnable(GL_CULL_FACE);
	else 
		glDisable(GL_CULL_FACE);
}

// ----------------------------------------------------------------------------

// Can't send color down as a pointer to aiColor4D because AI colors are ABGR.
void Color4f(const struct aiColor4D *color)
{
	glColor4f(color->r, color->g, color->b, color->a);
}

// ----------------------------------------------------------------------------
void recursive_render (const struct aiScene *sc, const struct aiNode* nd)
{
	int i;
	unsigned int n = 0, t;
	struct aiMatrix4x4 m = nd->mTransformation;

	// update transform
	aiTransposeMatrix4(&m);
	glPushMatrix();
	glMultMatrixf((float*)&m);

	// draw all meshes assigned to this node
	for (; n < nd->mNumMeshes; ++n) {
		const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]];

		apply_material(sc->mMaterials[mesh->mMaterialIndex]);

		if(mesh->mNormals == NULL) {
			glDisable(GL_LIGHTING);
		} else {
			glEnable(GL_LIGHTING);
		}

		if(mesh->mColors[0] != NULL) {
			glEnable(GL_COLOR_MATERIAL);
		} else {
			glDisable(GL_COLOR_MATERIAL);
		}

		for (t = 0; t < mesh->mNumFaces; ++t) {
			const struct aiFace* face = &mesh->mFaces[t];
			GLenum face_mode;

			switch(face->mNumIndices) {
				case 1: face_mode = GL_POINTS; break;
				case 2: face_mode = GL_LINES; break;
				case 3: face_mode = GL_TRIANGLES; break;
				default: face_mode = GL_POLYGON; break;
			}

			glBegin(face_mode);

			for(i = 0; i < face->mNumIndices; i++) {
				int index = face->mIndices[i];
				if(mesh->mColors[0] != NULL)
					Color4f(&mesh->mColors[0][index]);
				if(mesh->mNormals != NULL) 
					glNormal3fv(&mesh->mNormals[index].x);
				glVertex3fv(&mesh->mVertices[index].x);
			}

			glEnd();
		}

	}

	// draw all children
	for (n = 0; n < nd->mNumChildren; ++n) {
		recursive_render(sc, nd->mChildren[n]);
	}

	glPopMatrix();
}

// ----------------------------------------------------------------------------
void do_motion (void)
{
	static GLint prev_time = 0;

	int time = glutGet(GLUT_ELAPSED_TIME);
	angle += (time-prev_time)*0.01;
	prev_time = time;

	glutPostRedisplay ();
}

// ----------------------------------------------------------------------------
void display(void)
{
	float tmp;

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(0.f,0.f,3.f,0.f,0.f,-5.f,0.f,1.f,0.f);

	// rotate it around the y axis
	glRotatef(angle,0.f,1.f,0.f);

	// scale the whole asset to fit into our view frustum 
	tmp = scene_max.x-scene_min.x;
	tmp = aisgl_max(scene_max.y - scene_min.y,tmp);
	tmp = aisgl_max(scene_max.z - scene_min.z,tmp);
	tmp = 1.f / tmp;
	glScalef(tmp, tmp, tmp);

        // center the model
	glTranslatef( -scene_center.x, -scene_center.y, -scene_center.z );

        // if the display list has not been made yet, create a new one and
        // fill it with scene contents
	if(scene_list == 0) {
	    scene_list = glGenLists(1);
	    glNewList(scene_list, GL_COMPILE);
            // now begin at the root node of the imported data and traverse
            // the scenegraph by multiplying subsequent local transforms
            // together on GL's matrix stack.
	    recursive_render(scene, scene->mRootNode);
	    glEndList();
	}

	glCallList(scene_list);

	glutSwapBuffers();

	do_motion();
}

// ----------------------------------------------------------------------------
int loadasset (const char* path)
{
	// we are taking one of the postprocessing presets to avoid
	// writing 20 single postprocessing flags here.
	scene = aiImportFile(path,aiProcessPreset_TargetRealtime_Quality);

	if (scene) {
		get_bounding_box(&scene_min,&scene_max);
		scene_center.x = (scene_min.x + scene_max.x) / 2.0f;
		scene_center.y = (scene_min.y + scene_max.y) / 2.0f;
		scene_center.z = (scene_min.z + scene_max.z) / 2.0f;
		return 0;
	}
	return 1;
}

// ----------------------------------------------------------------------------
int main(int argc, char **argv)
{
	struct aiLogStream stream;

	glutInitWindowSize(900,600);
	glutInitWindowPosition(100,100);
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
	glutInit(&argc, argv);

	glutCreateWindow("Assimp - Very simple OpenGL sample");
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);

	// get a handle to the predefined STDOUT log stream and attach
	// it to the logging system. It will be active for all further
	// calls to aiImportFile(Ex) and aiApplyPostProcessing.
	stream = aiGetPredefinedLogStream(aiDefaultLogStream_STDOUT,NULL);
	aiAttachLogStream(&stream);

	// ... exactly the same, but this stream will now write the
	// log file to assimp_log.txt
	stream = aiGetPredefinedLogStream(aiDefaultLogStream_FILE,"assimp_log.txt");
	aiAttachLogStream(&stream);

	// the model name can be specified on the command line. we try to locate
	// one of the more expressive test models from the repository.
	if( 0 != loadasset( argc >= 2 ? argv[1] : "../../test/models-nonbsd/X/dwarf.x")) {
		if( argc != 1 || 0 != loadasset( "../../../../test/models-nonbsd/X/dwarf.x") && 0 != loadasset( "../../test/models/X/Testwuson.X")) { 
			return -1;
		}
	}

	glClearColor(0.1f,0.1f,0.1f,1.f);

	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);    // Uses default lighting parameters

	glEnable(GL_DEPTH_TEST);

	glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);
	glEnable(GL_NORMALIZE);

	// XXX docs say all polygons are emitted CCW, but tests show that some aren't.
	if(getenv("MODEL_IS_BROKEN"))  
		glFrontFace(GL_CW);

	glColorMaterial(GL_FRONT_AND_BACK, GL_DIFFUSE);

	glutGet(GLUT_ELAPSED_TIME);
	glutMainLoop();

	// cleanup - calling 'aiReleaseImport' is important, as the library 
	// keeps internal resources until the scene is freed again. Not 
	// doing so can cause severe resource leaking.
	aiReleaseImport(scene);

	// We added a log stream to the library, it's our job to disable it
	// again. This will definitely release the last resources allocated
	// by Assimp.
	aiDetachAllLogStreams();
	return 0;
}
