From 135d8d8a02341719302158e7beade95fae2daf95 Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Sat, 20 May 2023 06:50:10 +0300
Subject: [PATCH] distance function generation from level data, first pass

---
 Makefile              |    8 ++--
 sdr/raydungeon.p.glsl |  116 ++++++++++++++++++++++++++++++++++++++++++++++++-
 src/darray.h          |   12 ++---
 src/game.c            |    7 ++-
 src/game.h            |    1 +
 src/level.c           |   67 +++++++++++++++++++++++++---
 src/level.h           |    2 +
 src/options.c         |    3 ++
 src/scr_game.c        |   28 +++++++-----
 src/scr_lvled.c       |    8 ++++
 10 files changed, 221 insertions(+), 31 deletions(-)

diff --git a/Makefile b/Makefile
index 9c0f1ce..0af9e1a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,13 @@
-src = $(wildcard src/*.c)
+src = $(wildcard src/*.c) libs/glew/glew.c
 obj = $(src:.c=.o)
 dep = $(src:.c=.d)
 bin = game
 
 warn = -pedantic -Wall
 dbg = -g
-def = -DMINIGLUT_USE_LIBC
+def = -DMINIGLUT_USE_LIBC -DGLEW_STATIC
 
-inc = -Ilibs -Ilibs/assfile -Ilibs/treestor/include
+inc = -Ilibs -Ilibs/assfile -Ilibs/treestor/include -Ilibs/glew
 libs = -lassfile -ldrawtext -lgoat3d -limago -ltreestor
 
 CFLAGS = $(warn) $(opt) $(dbg) $(inc) $(def) -MMD
@@ -24,7 +24,7 @@ ifeq ($(sys), mingw)
 
 	libdir = -Llibs/w32
 else
-	libgl = -lGL -lGLU -lX11
+	libgl = -lGL -lX11
 
 	libdir = -Llibs/unix
 endif
diff --git a/sdr/raydungeon.p.glsl b/sdr/raydungeon.p.glsl
index 8a66df7..c10be18 100644
--- a/sdr/raydungeon.p.glsl
+++ b/sdr/raydungeon.p.glsl
@@ -1,5 +1,117 @@
+uniform float aspect;
+uniform mat4 matrix;
+uniform mat3 dirmatrix;
+
+#define DIST_THRES	1e-3
+#define MAX_ITER	250
+#define MAX_STEP	1.0
+
+vec3 raymarch(inout vec3 p, in vec3 dir, out float depth);
+vec3 shade(in vec3 p, in vec3 dir, in float dist, in float total_dist);
+vec3 backdrop(in vec3 dir);
+float eval_sdf(in vec3 p);
+vec3 eval_grad(in vec3 p, float dist);
+vec3 primray(in vec2 uv, out vec3 org);
+
+float boxdist(in vec3 p, in vec3 b);
+float sphdist(in vec3 p, in vec3 sp, in float srad);
+
 void main()
 {
-	vec3 col = vec3(gl_TexCoord[0].st, 1.0);
-	gl_FragColor = vec4(col, 1.0);
+	vec2 uv = gl_TexCoord[0].st;
+	vec3 rorg;
+	vec3 rdir = primray(uv, rorg);
+	float depth;
+
+	gl_FragColor.rgb = raymarch(rorg, rdir, depth);
+	gl_FragColor.a = 1.0;
+
+	vec4 projp = gl_ProjectionMatrix * vec4(0.0, 0.0, -depth, 1.0);
+	float zval = projp.z / projp.w;
+
+	gl_FragDepth = zval;
+}
+
+vec3 raymarch(inout vec3 p, in vec3 dir, out float depth)
+{
+	float d, total_d = 0.0;
+
+	for(int i=0; i<MAX_ITER; i++) {
+		if((d = eval_sdf(p)) <= DIST_THRES) {
+			depth = total_d;
+			return shade(p, dir, d, total_d);
+		}
+
+		d = min(d, MAX_STEP);
+
+		p = p + dir * d;
+		total_d += d;
+	}
+
+	depth = -gl_DepthRange.far;
+	return backdrop(dir);
+}
+
+vec3 shade(in vec3 p, in vec3 dir, in float dist, in float total_dist)
+{
+    const vec3 kd = vec3(1.0, 0.3, 0.1);
+    const vec3 ks = vec3(0.7, 0.7, 0.7);
+    const vec3 ldir = normalize(vec3(-1.0, 1.0, -1.5));
+    const vec3 vdir = vec3(0.0, 0.0, -1.0);
+
+    vec3 diffuse = vec3(0.0, 0.0, 0.0);
+    vec3 specular = vec3(0.0, 0.0, 0.0);
+    
+    vec3 n = eval_grad(p, dist);
+	return n * 0.5 + 0.5;
+    vec3 hdir = normalize(ldir + vdir);
+
+    float ndotl = max(dot(n, ldir), 0.0);
+    float ndoth = max(dot(n, hdir), 0.0);
+    
+    diffuse += kd * ndotl;
+    specular += ks * pow(ndoth, 50.0);
+    
+    float fog = clamp(300.0 / (total_dist * total_dist), 0.0, 1.0);
+
+    return mix(backdrop(dir), diffuse + specular, fog);
+}
+
+vec3 backdrop(in vec3 dir)
+{
+	return vec3(0.1, 0.1, 0.1);
+}
+
+#define DELTA	1e-4
+vec3 eval_grad(in vec3 p, float dist)
+{
+	float dfdx = eval_sdf(p + vec3(DELTA, 0.0, 0.0)) - dist;
+	float dfdy = eval_sdf(p + vec3(0.0, DELTA, 0.0)) - dist;
+	float dfdz = eval_sdf(p + vec3(0.0, 0.0, DELTA)) - dist;
+	return normalize(vec3(dfdx, dfdy, dfdz));
+}
+
+vec3 primray(in vec2 uv, out vec3 org)
+{
+	vec3 origin = (gl_ModelViewMatrixInverse * vec4(0.0, 0.0, 0.0, 1.0)).xyz;
+	org = origin;
+
+	vec2 nuv = uv * 2.0 - 1.0;
+	vec4 cp_near = vec4(nuv, -1.0, 1.0);
+
+	vec4 vdir = gl_ProjectionMatrixInverse * cp_near;
+	vec4 wdir = gl_ModelViewMatrixInverse * vec4(vdir.xyz, 0.0);
+
+	return normalize(wdir.xyz);
+}
+
+float boxdist(in vec3 p, in vec3 b)
+{
+	vec3 q = abs(p) - b;
+	return length(max(q, 0.0)) + min(max(q.x, max(q.y, q.z)), 0.0);
+}
+
+float sphdist(in vec3 p, in vec3 sp, in float srad)
+{
+	return length(p - sp) - srad;
 }
diff --git a/src/darray.h b/src/darray.h
index b9a7051..fd2594b 100644
--- a/src/darray.h
+++ b/src/darray.h
@@ -31,17 +31,17 @@ void *darr_finalize(void *da);
 #define darr_strpush(da, c) \
 	do { \
 		char cnull = 0, ch = (char)(c); \
-		(da) = dynarr_pop_impl(da); \
-		(da) = dynarr_push_impl((da), &ch); \
-		(da) = dynarr_push_impl((da), &cnull); \
+		(da) = darr_pop_impl(da); \
+		(da) = darr_push_impl((da), &ch); \
+		(da) = darr_push_impl((da), &cnull); \
 	} while(0)
 
 #define darr_strpop(da) \
 	do { \
 		char cnull = 0; \
-		(da) = dynarr_pop_impl(da); \
-		(da) = dynarr_pop_impl(da); \
-		(da) = dynarr_push_impl((da), &cnull); \
+		(da) = darr_pop_impl(da); \
+		(da) = darr_pop_impl(da); \
+		(da) = darr_push_impl((da), &cnull); \
 	} while(0)
 
 
diff --git a/src/game.c b/src/game.c
index f7306d6..f4a80e3 100644
--- a/src/game.c
+++ b/src/game.c
@@ -15,6 +15,7 @@ int fullscr;
 long time_msec;
 
 struct game_screen *cur_scr;
+char *start_scr_name;
 
 /* available screens */
 extern struct game_screen scr_menu, scr_game, scr_map, scr_lvled;
@@ -26,7 +27,7 @@ static int num_screens;
 int game_init(int argc, char **argv)
 {
 	int i;
-	char *start_scr_name;
+	char *env;
 
 	load_options(GAME_CFG_FILE);
 	if(parse_options(argc, argv) == -1) {
@@ -44,7 +45,9 @@ int game_init(int argc, char **argv)
 	screens[num_screens++] = &scr_map;
 	screens[num_screens++] = &scr_lvled;
 
-	start_scr_name = getenv("START_SCREEN");
+	if((env = getenv("START_SCREEN"))) {
+		start_scr_name = env;
+	}
 
 	for(i=0; i<num_screens; i++) {
 		if(screens[i]->init() == -1) {
diff --git a/src/game.h b/src/game.h
index 36e5854..7984996 100644
--- a/src/game.h
+++ b/src/game.h
@@ -45,6 +45,7 @@ extern int fullscr;
 
 extern long time_msec;
 extern struct game_screen *cur_scr;
+extern char *start_scr_name;
 
 
 int game_init(int argc, char **argv);
diff --git a/src/level.c b/src/level.c
index 4120867..dd0e3a1 100644
--- a/src/level.c
+++ b/src/level.c
@@ -180,6 +180,29 @@ int save_level(const struct level *lvl, const char *fname)
 			rect++;
 		}
 		fprintf(fp, "RECTEND\n\n");
+
+
+		fprintf(fp, "SDRSTART\n");
+		fprintf(fp, "float eval_sdf(in vec3 p)\n");
+		fprintf(fp, "{\n");
+		rect = lvl->rects;
+		for(i=0; i<num; i++) {
+			float cx = (rect->x - 0.5f + rect->w * 0.5f) * lvl->scale;
+			float cy = (rect->y - 0.5f + rect->h * 0.5f) * lvl->scale;
+			float rx = (rect->w + 0.1f) * lvl->scale * 0.5f;
+			float ry = (rect->h + 0.1f) * lvl->scale * 0.5f;
+
+			if(i == 0) {
+				fprintf(fp, "\tfloat d = boxdist(p - vec3(%f, 0.0, %f), vec3(%f, 1.0, %f));\n",
+						cx, cy, rx, ry);
+			} else {
+				fprintf(fp, "\td = min(d, boxdist(p - vec3(%f, 0.0, %f), vec3(%f, 1.0, %f)));\n",
+						cx, cy, rx, ry);
+			}
+			rect++;
+		}
+		fprintf(fp, "\treturn d;\n}\n");
+		fprintf(fp, "SDREND\n\n");
 	}
 
 	fclose(fp);
@@ -200,6 +223,13 @@ static char *clean_line(char *s)
 	return *s ? s : 0;
 }
 
+enum {
+	ST_HEADER,
+	ST_ASSIGN,
+	ST_MAP,
+	ST_SDR
+};
+
 int load_level(struct level *lvl, const char *fname)
 {
 	ass_file *fp;
@@ -209,6 +239,7 @@ int load_level(struct level *lvl, const char *fname)
 	int state = 0;
 	int i, nrow;
 	struct level_rect rect;
+	char *sdr = 0;
 
 	if(!(fp = ass_fopen(fname, "rb"))) {
 		fprintf(stderr, "load_level: failed to open: %s\n", fname);
@@ -217,16 +248,16 @@ int load_level(struct level *lvl, const char *fname)
 
 	while(ass_fgets(buf, sizeof buf, fp)) {
 		switch(state) {
-		case 0:
+		case ST_HEADER:
 			if(memcmp(buf, "RDLEVEL", 7) != 0) {
 				fprintf(stderr, "load_level: invalid level file: %s\n", fname);
 				ass_fclose(fp);
 				return -1;
 			}
-			state++;
+			state = ST_ASSIGN;
 			break;
 
-		case 1:
+		case ST_ASSIGN:
 			if(!(line = clean_line(buf)) || *line == '#') {
 				continue;
 			}
@@ -267,7 +298,15 @@ int load_level(struct level *lvl, const char *fname)
 
 				lvl->cells = calloc_nf(lvl->xsz * lvl->ysz, sizeof *lvl->cells);
 				nrow = 0;
-				state++;
+				state = ST_MAP;
+
+			} else if(strcmp(line, "SDRSTART") == 0) {
+				if(sdr) {
+					darr_clear(sdr);
+				} else {
+					sdr = darr_alloc(0, 1);
+				}
+				state = ST_SDR;
 
 			} else if(sscanf(line, "rect %d %d %d %d", &rect.x, &rect.y, &rect.w, &rect.h) == 4) {
 				rect.dbgcol[0] = (rand() & 0x7f) + 0x7f;
@@ -278,9 +317,9 @@ int load_level(struct level *lvl, const char *fname)
 			}
 			break;
 
-		case 2:
+		case ST_MAP:
 			if(memcmp(buf, "MAPEND", 6) == 0) {
-				state = 1;
+				state = ST_ASSIGN;
 				break;
 			}
 			for(i=0; i<lvl->xsz; i++) {
@@ -288,13 +327,27 @@ int load_level(struct level *lvl, const char *fname)
 				parse_cell(lvl, i, nrow, buf[i]);
 			}
 			if(++nrow >= lvl->ysz) {
-				state = 1;
+				state = ST_ASSIGN;
 				break;
 			}
 			break;
+
+		case ST_SDR:
+			if(memcmp(buf, "SDREND", 6) == 0) {
+				state = ST_ASSIGN;
+				break;
+			}
+			for(i=0; buf[i]; i++) {
+				darr_strpush(sdr, buf[i]);
+			}
+			break;
 		}
 	}
 
+	if(sdr) {
+		lvl->sdf_src = darr_finalize(sdr);
+	}
+
 	ass_fclose(fp);
 	return 0;
 }
diff --git a/src/level.h b/src/level.h
index 0a1a605..e3b53fe 100644
--- a/src/level.h
+++ b/src/level.h
@@ -24,6 +24,8 @@ struct level {
 	int sx, sy;
 
 	struct level_rect *rects;	/* darr, empty spaces */
+
+	char *sdf_src;
 };
 
 void init_level(struct level *lvl);
diff --git a/src/options.c b/src/options.c
index 34dee8f..b4964f9 100644
--- a/src/options.c
+++ b/src/options.c
@@ -3,6 +3,7 @@
 #include <string.h>
 #include <errno.h>
 #include "options.h"
+#include "game.h"
 #include "treestor.h"
 
 #define DEF_XRES		1280
@@ -40,6 +41,8 @@ int parse_options(int argc, char **argv)
 					fprintf(stderr, "%s must be followed by a screen name\n", argv[i - 1]);
 					return -1;
 				}
+				start_scr_name = argv[i];
+
 			} else if(strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "-help") == 0) {
 				printf(usage_fmt, argv[0]);
 				exit(0);
diff --git a/src/scr_game.c b/src/scr_game.c
index 2f1f31b..d19ff70 100644
--- a/src/scr_game.c
+++ b/src/scr_game.c
@@ -35,18 +35,13 @@ static cgm_vec3 cam_pan;
 
 static unsigned int sdr;
 
-
 static int ginit(void)
 {
-	if(!(sdr = create_program_load("sdr/raydungeon.v.glsl", "sdr/raydungeon.p.glsl"))) {
-		return -1;
-	}
 	return 0;
 }
 
 static void gdestroy(void)
 {
-	free_program(sdr);
 }
 
 static int gstart(void)
@@ -59,6 +54,19 @@ static int gstart(void)
 	cam_pan.x = -(lvl->xsz / 2.0f) * lvl->scale;
 	cam_pan.y = 0;
 	cam_pan.z = -(lvl->ysz / 2.0f) * lvl->scale;
+
+	glEnable(GL_DEPTH_TEST);
+
+	if(lvl->sdf_src) {
+		add_shader_footer(GL_FRAGMENT_SHADER, lvl->sdf_src);
+	} else {
+		add_shader_footer(GL_FRAGMENT_SHADER, "float eval_sdf(in vec3 p) { return 10000.0; }\n");
+	}
+	if(!(sdr = create_program_load("sdr/raydungeon.v.glsl", "sdr/raydungeon.p.glsl"))) {
+		return -1;
+	}
+	clear_shader_footer(GL_FRAGMENT_SHADER);
+	glUseProgram(sdr);
 	return 0;
 }
 
@@ -66,6 +74,8 @@ static void gstop(void)
 {
 	destroy_level(lvl);
 	free(lvl);
+
+	free_program(sdr);
 }
 
 static void gdisplay(void)
@@ -85,13 +95,11 @@ static void gdisplay(void)
 
 	glUseProgram(sdr);
 
-	glDepthMask(0);
 	glBegin(GL_TRIANGLES);
 	glTexCoord2f(0, 0); glVertex2f(-1, -1);
-	glTexCoord2f(2, 0); glVertex2f(4, -1);
-	glTexCoord2f(0, 2); glVertex2f(-1, 4);
+	glTexCoord2f(2, 0); glVertex2f(3, -1);
+	glTexCoord2f(0, 2); glVertex2f(-1, 3);
 	glEnd();
-	glDepthMask(1);
 
 	glUseProgram(0);
 
@@ -118,7 +126,7 @@ static void gdisplay(void)
 
 static void greshape(int x, int y)
 {
-	cgm_mperspective(proj_mat, cgm_deg_to_rad(60), win_aspect, 0.5, 500.0);
+	cgm_mperspective(proj_mat, cgm_deg_to_rad(60), win_aspect, 0.5, 40.0);
 	glMatrixMode(GL_PROJECTION);
 	glLoadMatrixf(proj_mat);
 }
diff --git a/src/scr_lvled.c b/src/scr_lvled.c
index e06cd32..3b5eda3 100644
--- a/src/scr_lvled.c
+++ b/src/scr_lvled.c
@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <math.h>
 #include <GL/gl.h>
+#include "cgmath/cgmath.h"
 #include "game.h"
 #include "level.h"
 #include "util.h"
@@ -64,6 +65,8 @@ static void display(void)
 	struct level_cell *cell;
 	struct level_rect *rect;
 
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
 	glMatrixMode(GL_MODELVIEW);
 	glLoadIdentity();
 	glTranslatef(0, 0, -cam_dist);
@@ -113,6 +116,11 @@ static void display(void)
 
 static void reshape(int x, int y)
 {
+	float proj_mat[16];
+
+	cgm_mperspective(proj_mat, cgm_deg_to_rad(60), win_aspect, 0.5, 40.0);
+	glMatrixMode(GL_PROJECTION);
+	glLoadMatrixf(proj_mat);
 }
 
 static void keyb(int key, int press)
-- 
1.7.10.4