graphitemaster/def.c

## def.c
/*
 * A simple deferred renderer using OpenGL, C90 and SDL, plugin and use
 * with no issue at all. All code is public domain -- Dale Weiler 2012
 * a.k.a graphitemaster
 */
#include <SDL.h>
#include <SDL/SDL_opengl.h>
typedef struct  {
	GLuint fbo;
	GLuint diffuse_target,  diffuse_texture;
	GLuint position_target, position_texture;
	GLuint normals_target,  normals_texture;
	GLuint depthbuffer;
	GLuint width,height;
} r_fbo;
typedef struct {
	GLhandleARB shader_vert;
	GLhandleARB shader_frag;
	GLhandleARB shader_prog;
	const char  *vsfilename;
	const char  *fsfilename;
} r_shader;
typedef struct {
	r_shader *shader;
	r_fbo    *fbo;
	GLuint    width, height;
	GLuint    id_diffuse;
	GLuint    id_position;
	GLuint    id_normals;
} r_def;
typedef struct {
	r_shader *shader;
	GLuint    worldmatrix;
	float     rotation_x,rotation_y,rotation_z;
	float     position_x,position_y,position_z;
	GLuint    texture, ogltex;
} r_mdl;

r_shader *r_shader_make(const char *vsfilename, const char *fsfilename) {
	r_shader *shader    = malloc(sizeof(r_shader));
	shader->vsfilename  = vsfilename;
	shader->fsfilename  = fsfilename;
	shader->shader_vert = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
	shader->shader_frag = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
	char *vd,*fd;
	FILE *sf    = NULL;
	long  count = 0;

	/* vertex load */
	sf = fopen(vsfilename, "r");
	if  (!sf) {
		printf("r: failed to load vertex shader %s\n", vsfilename);
		abort ();
	}
	fseek(sf, 0, SEEK_END);
	count = ftell(sf);
	rewind(sf);
	vd = malloc(count + 1);
	memset(vd, 0, count+1);
	fread (vd, 1, count, sf);
	fclose(sf); sf = NULL;
	/* fragment load */
	sf = fopen(fsfilename, "r");
	if  (!sf) {
		printf("r: failed to load fragment shader %s\n", fsfilename);
		abort ();
	}
	fseek(sf, 0, SEEK_END);
	count = ftell(sf);
	rewind(sf);
	fd = malloc(count + 1);
	memset(fd, 0, count+1);
	fread (fd, 1, count, sf);
	fclose(sf); sf = NULL;
	int compiled = 0;
	glShaderSourceARB        (shader->shader_vert, 1, &vd, NULL);
	glCompileShaderARB       (shader->shader_vert);
	glGetObjectParameterivARB(shader->shader_vert, GL_OBJECT_COMPILE_STATUS_ARB, &compiled);
	if (compiled == 0) {
		printf("r: failed to compile vertex shader %s\n", vsfilename);
		abort ();
	}
	glShaderSourceARB        (shader->shader_frag, 1, &fd, NULL);
	glCompileShaderARB       (shader->shader_frag);
	glGetObjectParameterivARB(shader->shader_frag, GL_OBJECT_COMPILE_STATUS_ARB, &compiled);
	if (compiled == 0) {
		printf("r: failed to compile fragment shader %s\n", fsfilename);
		abort ();
	}
	shader->shader_prog = glCreateProgramObjectARB();
	glAttachObjectARB(shader->shader_prog, shader->shader_vert);
	glAttachObjectARB(shader->shader_prog, shader->shader_frag);
	glLinkProgramARB (shader->shader_prog);
	free(vd);
	free(fd);
	return shader;
}

r_mdl *r_mdl_make(const char *vsfilename, const char *fsfilename) {
	r_mdl *mdl       = malloc(sizeof(r_mdl));
	mdl->ogltex      = 0;
	mdl->shader      = r_shader_make(vsfilename, fsfilename);
	mdl->rotation_x  = mdl->rotation_y = mdl->rotation_z = 0;
	mdl->position_x  = mdl->position_y = mdl->position_z = 0;
	mdl->worldmatrix = glGetUniformLocationARB(mdl->shader->shader_prog, "t_pos");
	mdl->texture     = glGetUniformLocationARB(mdl->shader->shader_prog, "t_dif");
	return mdl;
}

r_def *r_def_make(int w, int h, r_fbo *fbo) {
	r_def *def       = malloc(sizeof(r_def));
	def->shader      = r_shader_make("data/dr.vs", "data/dr.fs");
	def->fbo         = fbo;
	def->width       = w;
	def->height      = h;
	def->id_diffuse  = glGetUniformLocationARB(def->shader->shader_prog, "t_dif");
	def->id_position = glGetUniformLocationARB(def->shader->shader_prog, "t_pos");
	def->id_normals  = glGetUniformLocationARB(def->shader->shader_prog, "t_nrm");
}

void r_def_render(const r_def *def) {
	glMatrixMode          (GL_PROJECTION);
	glPushMatrix          ();
	glLoadIdentity        ();
	glOrtho               (0, def->width, 0, def->height, 0.1f, 2);
	glMatrixMode          (GL_MODELVIEW);
	glPushMatrix          ();
	glUseProgramObjectARB (def->shader->shader_prog);
	glActiveTextureARB    (GL_TEXTURE0_ARB);
	glEnable              (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, def->fbo->diffuse_texture);
	glUniform1iARB        (def->id_diffuse, 0);
	glActiveTextureARB    (GL_TEXTURE1_ARB);
	glEnable              (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, def->fbo->position_texture);
	glUniform1iARB        (def->id_position,1);
	glActiveTextureARB    (GL_TEXTURE2_ARB);
	glEnable              (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, def->fbo->normals_texture);
	glUniform1iARB        (def->id_normals, 2);
	glLoadIdentity        ();
	glColor3f             (1,1,1);
	glTranslatef          (0,0,-1.0);
	glBegin               (GL_QUADS);
	glTexCoord2f          (0, 0); glVertex3f(0.0f, 0.0f, 0.0f);
	glTexCoord2f          (1, 0); glVertex3f((float)def->width, 0.0f,               0.0f);
	glTexCoord2f          (1, 1); glVertex3f((float)def->width, (float)def->height, 0.0f);
	glTexCoord2f          (0, 1); glVertex3f(0.0f,              (float)def->height, 0.0f);
	glEnd                 ();
	glActiveTextureARB    (GL_TEXTURE0_ARB);
	glDisable             (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, 0);
	glActiveTextureARB    (GL_TEXTURE1_ARB);
	glDisable             (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, 0);
	glActiveTextureARB    (GL_TEXTURE1_ARB);
	glDisable             (GL_TEXTURE_2D);
	glBindTexture         (GL_TEXTURE_2D, 0);
	glUseProgramObjectARB (0);
	glMatrixMode          (GL_PROJECTION);
	glPopMatrix           ();
	glMatrixMode          (GL_MODELVIEW);
	glPopMatrix           ();
}

r_fbo *r_fbo_make(int w, int h) {
	r_fbo *fbo  = malloc(sizeof(r_fbo));
	fbo->width  = w;
	fbo->height = h;
	glGenFramebuffersEXT(1, &fbo->fbo);
	glGenFramebuffersEXT(1, &fbo->diffuse_target);
	glGenFramebuffersEXT(1, &fbo->position_target);
	glGenFramebuffersEXT(1, &fbo->normals_target);
	glGenFramebuffersEXT(1, &fbo->depthbuffer);
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo);

	glBindRenderbufferEXT       (GL_RENDERBUFFER_EXT, fbo->diffuse_target);
	glRenderbufferStorageEXT    (GL_RENDERBUFFER_EXT, GL_RGBA, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, fbo->diffuse_target);
	glBindRenderbufferEXT       (GL_RENDERBUFFER_EXT, fbo->position_target);
	glRenderbufferStorageEXT    (GL_RENDERBUFFER_EXT, GL_RGBA32F_ARB, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT1_EXT, GL_RENDERBUFFER_EXT, fbo->position_target);
	glBindRenderbufferEXT       (GL_RENDERBUFFER_EXT, fbo->normals_target);
	glRenderbufferStorageEXT    (GL_RENDERBUFFER_EXT, GL_RGBA16F_ARB, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT2_EXT, GL_RENDERBUFFER_EXT, fbo->normals_target);
	glBindRenderbufferEXT       (GL_RENDERBUFFER_EXT, fbo->depthbuffer);
	glRenderbufferStorageEXT    (GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_DEPTH_ATTACHMENT_EXT,  GL_RENDERBUFFER_EXT, fbo->depthbuffer);

	glGenTextures(1, &fbo->diffuse_texture);
	glGenTextures(1, &fbo->position_texture);
	glGenTextures(1, &fbo->normals_texture);

	glBindTexture  (GL_TEXTURE_2D, fbo->diffuse_texture);
	glTexImage2D   (GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, fbo->diffuse_texture, 0);
	glBindTexture  (GL_TEXTURE_2D, fbo->position_texture);
	glTexImage2D   (GL_TEXTURE_2D, 0, GL_RGBA32F_ARB, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, fbo->position_texture, 0);
	glBindTexture  (GL_TEXTURE_2D, fbo->normals_texture);
	glTexImage2D   (GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT2_EXT, GL_TEXTURE_2D, fbo->normals_texture, 0);
	GLenum check = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
	if (check != GL_FRAMEBUFFER_COMPLETE_EXT) {
		printf("r: failed to complete FBO target creation\n");
		abort();
	}
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	return fbo;
}

void r_fbo_start(const r_fbo *fbo) {
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo);
	glPushAttrib        (GL_VIEWPORT_BIT);
	glViewport          (0, 0, fbo->width, fbo->height);
	glClear             (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glClearColor        (0.0f, 0.0f, 0.0f, 1.0f);
	glActiveTextureARB  (GL_TEXTURE0_ARB);
	glEnable            (GL_TEXTURE_2D);
	GLenum buffers[] = {
		GL_COLOR_ATTACHMENT0_EXT,GL_COLOR_ATTACHMENT1_EXT,GL_COLOR_ATTACHMENT2_EXT
	};
	glDrawBuffers(3, buffers);
}
void r_fbo_stop (const r_fbo *fbo) {
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	glPopAttrib         ();
}
void r_fbo_show (const r_fbo *fbo, GLuint i, float sx, float sy, float x, float y) {
	GLuint tex = fbo->diffuse_texture;
	if (i == 1) tex = fbo->position_texture;
	else if (i == 2) tex = fbo->normals_texture;

	glMatrixMode      (GL_PROJECTION);
	glPushMatrix      ();
	glLoadIdentity    ();
	glOrtho           (0, fbo->width, 0, fbo->height, 0.1f, 2);
	glMatrixMode      (GL_MODELVIEW);
	glPushMatrix      ();
	glActiveTextureARB(GL_TEXTURE0_ARB);
	glLoadIdentity    ();
	glTranslatef      (x, -y, -1.0f);
	glColor3f         (1,1,1);
	glBegin           (GL_QUADS);
	glTexCoord2f      (0, 1); glVertex3f(0.0f, (float)fbo->height, 0.0f);
	glTexCoord2f      (0, 0); glVertex3f(0.0f, fbo->height-sy,     0.0f);
	glTexCoord2f      (1, 0); glVertex3f(sx,   fbo->height-sy,     0.0f);
	glTexCoord2f      (1, 1); glVertex3f(sx,   (float)fbo->height, 0.0f);
	glEnd             ();
	glBindTexture     (GL_TEXTURE_2D, 0);
	glMatrixMode      (GL_PROJECTION);
	glPopMatrix       ();
	glMatrixMode      (GL_MODELVIEW);
	glPopMatrix       ();
}
void r_mdl_render(r_mdl *mdl, int type) {
	glPushMatrix();

	switch (type) {
		/*
		 * Write all rendering in here, for some model
		 */
	}

	glUseProgramObjectARB(0);
	glPopMatrix();
}
int main() {
	const SDL_VideoInfo *info = NULL;
	int width  = 0;
    int height = 0;
    int bpp    = 0;
    int flags  = 0;
	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
		printf("c: failed to initialize video %s\n", SDL_GetError());
		abort ();
	}
	info = SDL_GetVideoInfo();
	if (!info) {
		printf("c: failed to query video %s\n", SDL_GetError());
		abort ();
	}
	width  = 640;
	height = 480;
	bpp    = info->vfmt->BitsPerPixel;
	SDL_GL_SetAttribute(SDL_GL_RED_SIZE,     5 );
    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE,   5 );
    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE,    5 );
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE,   16);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1 );

    flags  = SDL_OPENGL;
    if (SDL_SetVideoMode(width, height, bpp, flags) == 0) {
		printf("c: failed to set view mode: %s\n", SDL_GetError());
		abort ();
	}


	r_fbo *multi      = r_fbo_make(width, height);
	r_def *defer      = r_def_make(width, height, multi);
	r_mdl *level      = r_mdl_make([[VERTEX_SHADER_FILE_STRING_HERE]], [[FRAGMENT_SHADER_FILE_STRING_HERE]]);
	/* more models are allowed */
	level->position_x = 2;
	level->position_y = 2.5f;
	level->position_z = 0;
	glDisable   (GL_LIGHTING);
	glEnable    (GL_TEXTURE_2D);
	glShadeModel(GL_SMOOTH);
	glEnable    (GL_DEPTH_TEST);
	glDepthFunc (GL_LEQUAL);
	glHint      (GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	SDL_Event e;
	for (;;) {
		while (SDL_PollEvent(&e))
			switch (e.type)
				case SDL_QUIT: abort(); break;
		glClear       (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glClearColor  (0.2f, 0.3f, 0.8f, 1.0f);
		glLoadIdentity();
		glRotatef     (20, 1, 0, 0);
		glTranslatef  (0.0f, -4.6f, -10.0f);
		r_fbo_start   (multi);
		r_mdl_render  (level, __COUNTER__); /* handle more models as needed */
		r_fbo_stop    (multi);
		/*
		 * There is a choice now:
		 * 	#1 use the deferred renderer
		 * 	#2 use the fixed    renderer (to FBO)
		 */
		r_def_render(defer);
		/*
		 * Replace r_def_render(defer) with r_fbo_show(....)
		 * to use the fixed pipeline.
		 */
		SDL_GL_SwapBuffers();
	}
}
	/*
	* A simple deferred renderer using OpenGL, C90 and SDL, plugin and use
	* with no issue at all. All code is public domain -- Dale Weiler 2012
	* a.k.a graphitemaster
	*/
	#include <SDL.h>
	#include <SDL/SDL_opengl.h>
	typedef struct {
	GLuint fbo;
	GLuint diffuse_target, diffuse_texture;
	GLuint position_target, position_texture;
	GLuint normals_target, normals_texture;
	GLuint depthbuffer;
	GLuint width,height;
	} r_fbo;
	typedef struct {
	GLhandleARB shader_vert;
	GLhandleARB shader_frag;
	GLhandleARB shader_prog;
	const char *vsfilename;
	const char *fsfilename;
	} r_shader;
	typedef struct {
	r_shader *shader;
	r_fbo *fbo;
	GLuint width, height;
	GLuint id_diffuse;
	GLuint id_position;
	GLuint id_normals;
	} r_def;
	typedef struct {
	r_shader *shader;
	GLuint worldmatrix;
	float rotation_x,rotation_y,rotation_z;
	float position_x,position_y,position_z;
	GLuint texture, ogltex;
	} r_mdl;

	r_shader r_shader_make(const char vsfilename, const char *fsfilename) {
	r_shader *shader = malloc(sizeof(r_shader));
	shader->vsfilename = vsfilename;
	shader->fsfilename = fsfilename;
	shader->shader_vert = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
	shader->shader_frag = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
	char vd,fd;
	FILE *sf = NULL;
	long count = 0;

	/* vertex load */
	sf = fopen(vsfilename, "r");
	if (!sf) {
	printf("r: failed to load vertex shader %s\n", vsfilename);
	abort ();
	}
	fseek(sf, 0, SEEK_END);
	count = ftell(sf);
	rewind(sf);
	vd = malloc(count + 1);
	memset(vd, 0, count+1);
	fread (vd, 1, count, sf);
	fclose(sf); sf = NULL;
	/* fragment load */
	sf = fopen(fsfilename, "r");
	if (!sf) {
	printf("r: failed to load fragment shader %s\n", fsfilename);
	abort ();
	}
	fseek(sf, 0, SEEK_END);
	count = ftell(sf);
	rewind(sf);
	fd = malloc(count + 1);
	memset(fd, 0, count+1);
	fread (fd, 1, count, sf);
	fclose(sf); sf = NULL;
	int compiled = 0;
	glShaderSourceARB (shader->shader_vert, 1, &vd, NULL);
	glCompileShaderARB (shader->shader_vert);
	glGetObjectParameterivARB(shader->shader_vert, GL_OBJECT_COMPILE_STATUS_ARB, &compiled);
	if (compiled == 0) {
	printf("r: failed to compile vertex shader %s\n", vsfilename);
	abort ();
	}
	glShaderSourceARB (shader->shader_frag, 1, &fd, NULL);
	glCompileShaderARB (shader->shader_frag);
	glGetObjectParameterivARB(shader->shader_frag, GL_OBJECT_COMPILE_STATUS_ARB, &compiled);
	if (compiled == 0) {
	printf("r: failed to compile fragment shader %s\n", fsfilename);
	abort ();
	}
	shader->shader_prog = glCreateProgramObjectARB();
	glAttachObjectARB(shader->shader_prog, shader->shader_vert);
	glAttachObjectARB(shader->shader_prog, shader->shader_frag);
	glLinkProgramARB (shader->shader_prog);
	free(vd);
	free(fd);
	return shader;
	}

	r_mdl r_mdl_make(const char vsfilename, const char *fsfilename) {
	r_mdl *mdl = malloc(sizeof(r_mdl));
	mdl->ogltex = 0;
	mdl->shader = r_shader_make(vsfilename, fsfilename);
	mdl->rotation_x = mdl->rotation_y = mdl->rotation_z = 0;
	mdl->position_x = mdl->position_y = mdl->position_z = 0;
	mdl->worldmatrix = glGetUniformLocationARB(mdl->shader->shader_prog, "t_pos");
	mdl->texture = glGetUniformLocationARB(mdl->shader->shader_prog, "t_dif");
	return mdl;
	}

	r_def r_def_make(int w, int h, r_fbo fbo) {
	r_def *def = malloc(sizeof(r_def));
	def->shader = r_shader_make("data/dr.vs", "data/dr.fs");
	def->fbo = fbo;
	def->width = w;
	def->height = h;
	def->id_diffuse = glGetUniformLocationARB(def->shader->shader_prog, "t_dif");
	def->id_position = glGetUniformLocationARB(def->shader->shader_prog, "t_pos");
	def->id_normals = glGetUniformLocationARB(def->shader->shader_prog, "t_nrm");
	}

	void r_def_render(const r_def *def) {
	glMatrixMode (GL_PROJECTION);
	glPushMatrix ();
	glLoadIdentity ();
	glOrtho (0, def->width, 0, def->height, 0.1f, 2);
	glMatrixMode (GL_MODELVIEW);
	glPushMatrix ();
	glUseProgramObjectARB (def->shader->shader_prog);
	glActiveTextureARB (GL_TEXTURE0_ARB);
	glEnable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, def->fbo->diffuse_texture);
	glUniform1iARB (def->id_diffuse, 0);
	glActiveTextureARB (GL_TEXTURE1_ARB);
	glEnable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, def->fbo->position_texture);
	glUniform1iARB (def->id_position,1);
	glActiveTextureARB (GL_TEXTURE2_ARB);
	glEnable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, def->fbo->normals_texture);
	glUniform1iARB (def->id_normals, 2);
	glLoadIdentity ();
	glColor3f (1,1,1);
	glTranslatef (0,0,-1.0);
	glBegin (GL_QUADS);
	glTexCoord2f (0, 0); glVertex3f(0.0f, 0.0f, 0.0f);
	glTexCoord2f (1, 0); glVertex3f((float)def->width, 0.0f, 0.0f);
	glTexCoord2f (1, 1); glVertex3f((float)def->width, (float)def->height, 0.0f);
	glTexCoord2f (0, 1); glVertex3f(0.0f, (float)def->height, 0.0f);
	glEnd ();
	glActiveTextureARB (GL_TEXTURE0_ARB);
	glDisable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, 0);
	glActiveTextureARB (GL_TEXTURE1_ARB);
	glDisable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, 0);
	glActiveTextureARB (GL_TEXTURE1_ARB);
	glDisable (GL_TEXTURE_2D);
	glBindTexture (GL_TEXTURE_2D, 0);
	glUseProgramObjectARB (0);
	glMatrixMode (GL_PROJECTION);
	glPopMatrix ();
	glMatrixMode (GL_MODELVIEW);
	glPopMatrix ();
	}

	r_fbo *r_fbo_make(int w, int h) {
	r_fbo *fbo = malloc(sizeof(r_fbo));
	fbo->width = w;
	fbo->height = h;
	glGenFramebuffersEXT(1, &fbo->fbo);
	glGenFramebuffersEXT(1, &fbo->diffuse_target);
	glGenFramebuffersEXT(1, &fbo->position_target);
	glGenFramebuffersEXT(1, &fbo->normals_target);
	glGenFramebuffersEXT(1, &fbo->depthbuffer);
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo);

	glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, fbo->diffuse_target);
	glRenderbufferStorageEXT (GL_RENDERBUFFER_EXT, GL_RGBA, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, fbo->diffuse_target);
	glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, fbo->position_target);
	glRenderbufferStorageEXT (GL_RENDERBUFFER_EXT, GL_RGBA32F_ARB, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT1_EXT, GL_RENDERBUFFER_EXT, fbo->position_target);
	glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, fbo->normals_target);
	glRenderbufferStorageEXT (GL_RENDERBUFFER_EXT, GL_RGBA16F_ARB, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_COLOR_ATTACHMENT2_EXT, GL_RENDERBUFFER_EXT, fbo->normals_target);
	glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, fbo->depthbuffer);
	glRenderbufferStorageEXT (GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, w, h);
	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT , GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, fbo->depthbuffer);

	glGenTextures(1, &fbo->diffuse_texture);
	glGenTextures(1, &fbo->position_texture);
	glGenTextures(1, &fbo->normals_texture);

	glBindTexture (GL_TEXTURE_2D, fbo->diffuse_texture);
	glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, fbo->diffuse_texture, 0);
	glBindTexture (GL_TEXTURE_2D, fbo->position_texture);
	glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA32F_ARB, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, fbo->position_texture, 0);
	glBindTexture (GL_TEXTURE_2D, fbo->normals_texture);
	glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT2_EXT, GL_TEXTURE_2D, fbo->normals_texture, 0);
	GLenum check = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
	if (check != GL_FRAMEBUFFER_COMPLETE_EXT) {
	printf("r: failed to complete FBO target creation\n");
	abort();
	}
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	return fbo;
	}

	void r_fbo_start(const r_fbo *fbo) {
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo);
	glPushAttrib (GL_VIEWPORT_BIT);
	glViewport (0, 0, fbo->width, fbo->height);
	glClear (GL_COLOR_BUFFER_BIT \| GL_DEPTH_BUFFER_BIT);
	glClearColor (0.0f, 0.0f, 0.0f, 1.0f);
	glActiveTextureARB (GL_TEXTURE0_ARB);
	glEnable (GL_TEXTURE_2D);
	GLenum buffers[] = {
	GL_COLOR_ATTACHMENT0_EXT,GL_COLOR_ATTACHMENT1_EXT,GL_COLOR_ATTACHMENT2_EXT
	};
	glDrawBuffers(3, buffers);
	}
	void r_fbo_stop (const r_fbo *fbo) {
	glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	glPopAttrib ();
	}
	void r_fbo_show (const r_fbo *fbo, GLuint i, float sx, float sy, float x, float y) {
	GLuint tex = fbo->diffuse_texture;
	if (i == 1) tex = fbo->position_texture;
	else if (i == 2) tex = fbo->normals_texture;

	glMatrixMode (GL_PROJECTION);
	glPushMatrix ();
	glLoadIdentity ();
	glOrtho (0, fbo->width, 0, fbo->height, 0.1f, 2);
	glMatrixMode (GL_MODELVIEW);
	glPushMatrix ();
	glActiveTextureARB(GL_TEXTURE0_ARB);
	glLoadIdentity ();
	glTranslatef (x, -y, -1.0f);
	glColor3f (1,1,1);
	glBegin (GL_QUADS);
	glTexCoord2f (0, 1); glVertex3f(0.0f, (float)fbo->height, 0.0f);
	glTexCoord2f (0, 0); glVertex3f(0.0f, fbo->height-sy, 0.0f);
	glTexCoord2f (1, 0); glVertex3f(sx, fbo->height-sy, 0.0f);
	glTexCoord2f (1, 1); glVertex3f(sx, (float)fbo->height, 0.0f);
	glEnd ();
	glBindTexture (GL_TEXTURE_2D, 0);
	glMatrixMode (GL_PROJECTION);
	glPopMatrix ();
	glMatrixMode (GL_MODELVIEW);
	glPopMatrix ();
	}
	void r_mdl_render(r_mdl *mdl, int type) {
	glPushMatrix();

	switch (type) {
	/*
	* Write all rendering in here, for some model
	*/
	}

	glUseProgramObjectARB(0);
	glPopMatrix();
	}
	int main() {
	const SDL_VideoInfo *info = NULL;
	int width = 0;
	int height = 0;
	int bpp = 0;
	int flags = 0;
	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
	printf("c: failed to initialize video %s\n", SDL_GetError());
	abort ();
	}
	info = SDL_GetVideoInfo();
	if (!info) {
	printf("c: failed to query video %s\n", SDL_GetError());
	abort ();
	}
	width = 640;
	height = 480;
	bpp = info->vfmt->BitsPerPixel;
	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5 );
	SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5 );
	SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5 );
	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1 );

	flags = SDL_OPENGL;
	if (SDL_SetVideoMode(width, height, bpp, flags) == 0) {
	printf("c: failed to set view mode: %s\n", SDL_GetError());
	abort ();
	}


	r_fbo *multi = r_fbo_make(width, height);
	r_def *defer = r_def_make(width, height, multi);
	r_mdl *level = r_mdl_make([[VERTEX_SHADER_FILE_STRING_HERE]], [[FRAGMENT_SHADER_FILE_STRING_HERE]]);
	/* more models are allowed */
	level->position_x = 2;
	level->position_y = 2.5f;
	level->position_z = 0;
	glDisable (GL_LIGHTING);
	glEnable (GL_TEXTURE_2D);
	glShadeModel(GL_SMOOTH);
	glEnable (GL_DEPTH_TEST);
	glDepthFunc (GL_LEQUAL);
	glHint (GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	SDL_Event e;
	for (;;) {
	while (SDL_PollEvent(&e))
	switch (e.type)
	case SDL_QUIT: abort(); break;
	glClear (GL_COLOR_BUFFER_BIT \| GL_DEPTH_BUFFER_BIT);
	glClearColor (0.2f, 0.3f, 0.8f, 1.0f);
	glLoadIdentity();
	glRotatef (20, 1, 0, 0);
	glTranslatef (0.0f, -4.6f, -10.0f);
	r_fbo_start (multi);
	r_mdl_render (level, __COUNTER__); /* handle more models as needed */
	r_fbo_stop (multi);
	/*
	* There is a choice now:
	* #1 use the deferred renderer
	* #2 use the fixed renderer (to FBO)
	*/
	r_def_render(defer);
	/*
	* Replace r_def_render(defer) with r_fbo_show(....)
	* to use the fixed pipeline.
	*/
	SDL_GL_SwapBuffers();
	}
	}