/*
 * render.c
 *
 * Render the scene
 *
 * (c) 2008 Thomas White <taw27@cam.ac.uk>
 *
 *  thrust3d - a silly game
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#define GL_GLEXT_PROTOTYPES 1
#include <gl.h>
#include <glext.h>
#include <SDL.h>
#include <glu.h>
#include <math.h>
#include <stdio.h>

#include "model.h"
#include "game.h"
#include "render.h"
#include "texture.h"
#include "utils.h"

/* Utility function to load and compile a shader, checking the info log */
static GLhandleARB render_load_shader(const char *filename, GLenum type) {

	GLhandleARB shader;
	char text[4096];
	size_t len;
	FILE *fh;
	int l;
	
	fh = fopen(filename, "r");
	if ( fh == NULL ) {
		fprintf(stderr, "Couldn't load shader '%s'\n", filename);
		return 0;
	}
	len = fread(text, 1, 4095, fh);
	fclose(fh);
	text[len] = '\0';
	const GLcharARB *source = text;
	shader = glCreateShaderObjectARB(type);
	glShaderSourceARB(shader, 1, &source, NULL);
	glCompileShaderARB(shader);
	glGetInfoLogARB(shader, 4095, &l, text);
	if ( l > 0 ) {
		printf("%s\n", text); fflush(stdout);
	}
	
	return shader;
	
}

static void render_load_shaders(RenderContext *ctx) {
	
	ctx->lighting_vert = render_load_shader(DATADIR"/shaders/lighting.vert", GL_VERTEX_SHADER_ARB);
	ctx->lighting_frag = render_load_shader(DATADIR"/shaders/lighting.frag", GL_FRAGMENT_SHADER_ARB);
	ctx->lighting_program = glCreateProgramObjectARB();
	glAttachObjectARB(ctx->lighting_program, ctx->lighting_vert);
	glAttachObjectARB(ctx->lighting_program, ctx->lighting_frag);
	glLinkProgramARB(ctx->lighting_program);
	
}

static void render_delete_shaders(RenderContext *ctx) {

	glDetachObjectARB(ctx->lighting_program, ctx->lighting_frag);
	glDetachObjectARB(ctx->lighting_program, ctx->lighting_vert);
	glDeleteObjectARB(ctx->lighting_vert);
	glDeleteObjectARB(ctx->lighting_frag);
	glDeleteObjectARB(ctx->lighting_program);

}

/* OpenGL initial setup */
RenderContext *render_setup(int width, int height) {
	
	RenderContext *ctx;
	
	ctx = malloc(sizeof(RenderContext));
	if ( ctx == NULL ) return NULL;
	
	ctx->width = width;
	ctx->height = height;
	ctx->aspect = (GLfloat)width/(GLfloat)height;
	
	glClearColor(0.0, 0.0, 0.0, 1.0);
	
	glEnable(GL_COLOR_MATERIAL);
	glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
	
	glFrontFace(GL_CCW);
	glEnable(GL_CULL_FACE);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_LIGHTING);
	
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	
	/* Create a small FBO for rendering reflections with */
	glGenFramebuffersEXT(1, &ctx->fbo);
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, ctx->fbo);
 	/* Add a (texture) colour buffer to the FBO */
	glGenTextures(1, &ctx->fbotex);
	glBindTexture(GL_TEXTURE_2D, ctx->fbotex);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, ctx->fbotex, 0);
	/* Add a depth buffer to the FBO */
	glGenRenderbuffersEXT(1, &ctx->fbodepth);
	glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, ctx->fbodepth);
	glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_STENCIL_EXT, 256, 256);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, ctx->fbodepth);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, ctx->fbodepth);
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	
	render_load_shaders(ctx);
	
	ctx->num_textures = 0;
	
	/* Load misc texture bits */
	texture_load(ctx, "radioactive");
	texture_load(ctx, "fuel");
	
	return ctx;
	
}

void render_shutdown(RenderContext *ctx) {
	render_delete_shaders(ctx);
	texture_free_all(ctx);
}

static GLenum render_gltype(PrimitiveType type) {

	switch ( type ) {
		case PRIMITIVE_QUADS : return GL_QUADS;
		case PRIMITIVE_TRIANGLES : return GL_TRIANGLES;
		default : break;
	}

	return GL_FALSE;

}

static int render_model_instance_draw(ModelInstance *instance, Uint32 t, RenderContext *ctx) {

	int j;
	Model *m;
	GLfloat x, y, z;
	GLfloat black[] = {0.0, 0.0, 0.0};
			
	m = instance->model;
	if ( m == NULL ) return 0;	/* No model to draw */
	x = instance->x;
	y = instance->y;
	z = instance->z;
	
	for ( j=0; j<m->num_primitives; j++ ) {
		
		Primitive *p;
		
		p = m->primitives[j];
		
		if ( p->attribs & ATTRIB_PULSE ) {
			float s;
			s = fabsf(cosf(t * 0.001));
			GLfloat c[] = {s*p->col_r, s*p->col_g, s*p->col_b};
			glMaterialfv(GL_FRONT, GL_EMISSION, c);
			glColor3f(0.3, 0.3, 0.3);
			glMaterialfv(GL_FRONT, GL_SPECULAR, black);
		} else if ( p->attribs & ATTRIB_COLOUR ) {
			glMaterialfv(GL_FRONT, GL_EMISSION, black);
			glMaterialfv(GL_FRONT, GL_SPECULAR, black);
			glColor3f(p->col_r, p->col_g, p->col_b);
		} else {
			glMaterialfv(GL_FRONT, GL_EMISSION, black);
			glMaterialfv(GL_FRONT, GL_SPECULAR, black);
			glColor3f(1.0, 1.0, 1.0);
		}
		
		/* Location and orientation */
		glPushMatrix();
		glTranslatef(x, y, z);
		glRotatef(rad2deg(instance->yaw), 0.0, 0.0, -1.0);	/* Minus sign defines +yaw as "right" */
		
		/* Texture */
		if ( p->texture != NULL ) {
			Texture *texture;
			texture = texture_lookup(ctx, p->texture);
			if ( texture != NULL ) {
				glBindTexture(GL_TEXTURE_2D, texture->texname);
				glEnable(GL_TEXTURE_2D);
				glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
			}
		}
		
		glVertexPointer(3, GL_FLOAT, 0, p->vertices);
		glNormalPointer(GL_FLOAT, 0, p->normals);
		glTexCoordPointer(2, GL_FLOAT, 0, p->texcoords);
		glDrawArrays(render_gltype(p->type), 0, p->num_vertices);
		
		glPopMatrix();
		
		glDisable(GL_TEXTURE_2D);
		
	}

	return 0;

}

static void render_draw_line(GLfloat x1, GLfloat y1, GLfloat z1, GLfloat x2, GLfloat y2, GLfloat z2) {

	GLfloat red[] = {1.0, 0.0, 0.0, 1.0};

	glMaterialfv(GL_FRONT, GL_EMISSION, red);
	glColor3f(0.0, 0.0, 0.0);
	
	glBegin(GL_LINES);
		glVertex3f(x1, y1, z1);
		glVertex3f(x2, y2, z2);
	glEnd();

}

static void render_draw_stuff(Game *game, Uint32 t) {
	
	int i;
	
	glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);
	glEnableClientState(GL_VERTEX_ARRAY);
	glEnableClientState(GL_NORMAL_ARRAY);
	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
	
	for ( i=0; i<game->num_rooms; i++ ) {
	
		Room *room;
		int j;
		
		room = game->rooms[i];
		if ( room == NULL ) return;
		
		//render_setup_lighting(game, room);
		
		for ( j=0; j<room->num_objects; j++ ) {
			GLfloat x, y, z;
			if ( room->objects[j] == NULL ) continue;
			x = room->rx - game->cur_room_x;
			y = room->ry - game->cur_room_y;
			z = room->rz - game->cur_room_z;
			glPushMatrix();
			glTranslatef(10.0*x, 10.0*y, 10.0*z);
			render_model_instance_draw(room->objects[j], t, game->render);
			glPopMatrix();
		}
		
	}
	
	glPopClientAttrib();
	
}

static void render_setup_lighting(Game *game) {

	GLfloat pos[] = {-1.0, -0.8, 1.3, 0.0};
	GLfloat ambient[4];
	GLfloat diffuse[] = {0.8, 0.8, 0.8, 1.0};
	GLfloat specular[] = {0.8, 0.8, 0.8, 1.0};

	glEnable(GL_LIGHTING);

	ambient[0] = 0.3;  ambient[1] = 0.3;  ambient[2] = 0.3;  ambient[3] = 1.0;
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambient);
	glLightfv(GL_LIGHT0, GL_POSITION, pos);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
	glLightfv(GL_LIGHT0, GL_SPECULAR, specular);
	glEnable(GL_LIGHT0);
	
}

static void render_draw_2d(RenderContext *r, Game *game) {

	Texture *texture;
	GLfloat cr, cg, cb;
	
	/* Set up transforms for 2D rendering */
	glClear(GL_DEPTH_BUFFER_BIT);
	glDisable(GL_LIGHTING);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	glScalef(0.95, 0.95, 1.0);
	
	/* Radiation symbol */
	texture = texture_lookup(r, "radioactive");
	if ( texture != NULL ) {
		glBindTexture(GL_TEXTURE_2D, texture->texname);
		glEnable(GL_TEXTURE_2D);
		glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	}
	glColor4f(1.0, 1.0, 1.0, 0.5);
	glBegin(GL_QUADS);	
		glTexCoord2f(0.0, 0.0);
		glVertex2f(-1.0, -1.0);			/* Bottom left */
		glTexCoord2f(1.0, 0.0);
		glVertex2f(-0.9, -1.0);			/* Bottom right */
		glTexCoord2f(1.0, 1.0);
		glVertex2f(-0.9, -1.0+0.1*r->aspect);	/* Top right */ 
		glTexCoord2f(0.0, 1.0);
		glVertex2f(-1.0, -1.0+0.1*r->aspect);	/* Top left */
	glEnd();
	glDisable(GL_TEXTURE_2D);
	
	/* Radiation meter */
	cg = 1.0 - game->radiation;
	glBegin(GL_QUADS);	
		glColor4f(1.0, 1.0, 0.0, 0.5);
		glVertex2f(-1.0, -0.8);			/* Bottom left */
		glVertex2f(-0.9, -0.8);			/* Bottom right */
		glColor4f(0.8, cg, 0.0, game->radiation);
		glVertex2f(-0.9, -0.8+(1.8*game->radiation));	/* Top right */ 
		glVertex2f(-1.0,  -0.8+(1.8*game->radiation));	/* Top left */
	glEnd();

	/* Fuel symbol */
	texture = texture_lookup(r, "fuel");
	if ( texture != NULL ) {
		glBindTexture(GL_TEXTURE_2D, texture->texname);
		glEnable(GL_TEXTURE_2D);
		glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	}
	glColor4f(1.0, 1.0, 1.0, 0.5);
	glBegin(GL_QUADS);	
		glTexCoord2f(0.0, 0.0);
		glVertex2f(0.9, -1.0);			/* Bottom left */
		glTexCoord2f(1.0, 0.0);
		glVertex2f(1.0, -1.0);			/* Bottom right */
		glTexCoord2f(1.0, 1.0);
		glVertex2f(1.0, -1.0+0.1*r->aspect);	/* Top right */ 
		glTexCoord2f(0.0, 1.0);
		glVertex2f(0.9, -1.0+0.1*r->aspect);	/* Top left */
	glEnd();
	glDisable(GL_TEXTURE_2D);
	
	/* Fuel meter */
	cr = 1.0 - game->fuel;
	cg = game->fuel;
	cb = 0.2 + 0.1*game->fuel;
	glBegin(GL_QUADS);	
		glColor4f(1.0, 0.0, 0.2, 0.5);
		glVertex2f(0.9, -0.8);			/* Bottom left */
		glVertex2f(1.0, -0.8);			/* Bottom right */
		glColor4f(cr, cg, cb, 0.5);
		glVertex2f(1.0, -0.8+(1.8*game->fuel));	/* Top right */ 
		glVertex2f(0.9, -0.8+(1.8*game->fuel));	/* Top left */
	glEnd();
	
}

void render_draw(Game *game, Uint32 t) {

	RenderContext *r;
	
	r = game->render;
	
	/* First pass: Looking upwards */
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, r->fbo);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glViewport(0, 0, 256, 256);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(70.0, 1.0, 0.1, 100.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(game->lander->x, game->lander->y, game->lander->z,
		  game->lander->x, game->lander->y, game->lander->z+10.0,
		  sqrtf(2.0)*sinf(game->lander->yaw), sqrtf(2.0)*cosf(game->lander->yaw), 0.0);
	render_setup_lighting(game);
	render_draw_stuff(game, t);
	
	/* Second pass: Main view */
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glViewport(0, 0, r->width, r->height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(50.0, (GLfloat)r->width/(GLfloat)r->height, 0.1, 100.0);	/* Depth buffer 10cm to 100m */
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(game->lander->x-(game->view_dist*sinf(game->lander->yaw)*cosf(game->view_angle)),
		  game->lander->y-(game->view_dist*cosf(game->lander->yaw)*cosf(game->view_angle)),
		  game->lander->z+(game->view_dist*sinf(game->view_angle)),
		  game->lander->x, game->lander->y, game->lander->z,
		  sqrtf(2.0)*sinf(game->lander->yaw)*sinf(game->view_angle),
		  sqrtf(2.0)*cosf(game->lander->yaw)*sinf(game->view_angle), sqrtf(2.0)*cosf(game->view_angle));	
	render_setup_lighting(game);
	render_draw_stuff(game, t);
	
	/* Finally, draw the lander */
	glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);
	glEnableClientState(GL_VERTEX_ARRAY);
	glEnableClientState(GL_NORMAL_ARRAY);
	glEnable(GL_TEXTURE_GEN_S);
	glEnable(GL_TEXTURE_GEN_T);
	glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
	glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
	render_model_instance_draw(game->lander, t, r);
	glPopClientAttrib();
	render_draw_line(game->lander->x, game->lander->y, game->lander->z, game->lander->x, game->lander->y, game->lander->z-200.0);
	glDisable(GL_TEXTURE_GEN_S);
	glDisable(GL_TEXTURE_GEN_T);
	
	render_draw_2d(r, game);
	
	SDL_GL_SwapBuffers();
	
}