# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1333576331 -10800
# Node ID f40e4edfee7e1ee1c2f8192e9e3f707d88c57c82
# Parent  04316e9e95dc531dc520fa28f6dde001576894be
shading

diff -r 04316e9e95dc -r f40e4edfee7e src/volray.c
--- a/src/volray.c	Wed Apr 04 01:37:58 2012 +0300
+++ b/src/volray.c	Thu Apr 05 00:52:11 2012 +0300
@@ -54,11 +54,12 @@
 int raytex_needs_recalc = 1;
 
 unsigned int xfer_tex;
-float xfer_mean = 0.5, xfer_sdev = 1.0;
+float xfer_mean = 0.7, xfer_sdev = 0.1;
 int xfertex_needs_recalc = 1;
 
 static int uimode;
-static float cur_z = 0.5;
+static float cur_z = 0.0;
+static float ray_step = 0.01;
 
 int main(int argc, char **argv)
 {
@@ -99,6 +100,8 @@
 	set_uniform_int(vol_sdr, "volume", 0);
 	set_uniform_int(vol_sdr, "ray_tex", 1);
 	set_uniform_int(vol_sdr, "xfer_tex", 2);
+	set_uniform_float(vol_sdr, "ray_step", ray_step);
+	set_uniform_float(vol_sdr, "zclip", cur_z);
 
 	if(!(slice_sdr = create_program_load(0, "slice.p.glsl"))) {
 		return -1;
@@ -127,7 +130,7 @@
 
 		if(i == 0) {
 			/* allocate storage for the texture */
-			glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA, xsz, ysz, nslices, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+			glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA32F, xsz, ysz, nslices, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 
 			vol_xsz = xsz;
 			vol_ysz = ysz;
@@ -388,6 +391,8 @@
 			cur_z = 0.0;
 		if(cur_z > 1.0)
 			cur_z = 1.0;
+
+		set_uniform_float(vol_sdr, "zclip", cur_z);
 		glutPostRedisplay();
 		break;
 
diff -r 04316e9e95dc -r f40e4edfee7e volray.p.glsl
--- a/volray.p.glsl	Wed Apr 04 01:37:58 2012 +0300
+++ b/volray.p.glsl	Thu Apr 05 00:52:11 2012 +0300
@@ -1,6 +1,8 @@
 uniform sampler3D volume;
 uniform sampler2D ray_tex;
 uniform sampler1D xfer_tex;
+uniform float ray_step;
+uniform float zclip;
 
 struct Ray {
 	vec3 origin, dir;
@@ -12,14 +14,14 @@
 
 struct ISect {
 	bool hit;
-	float t;
+	float t0, t1;
 	vec3 pos;
 	vec3 normal;
 };
 
 vec3 sky(Ray ray);
-vec3 ray_march(Ray ray);
-vec3 shade(Ray ray, ISect isect);
+vec3 ray_march(Ray ray, float t0, float t1);
+vec3 shade(Ray ray, vec3 pos, vec3 norm);
 Ray get_primary_ray();
 ISect intersect_aabb(Ray ray, AABBox aabb);
 
@@ -32,38 +34,44 @@
 
 	ISect res = intersect_aabb(ray, aabb);
 	if(res.hit) {
-		ray.origin += ray.dir * res.t;
-		color = ray_march(ray);
+		color = ray_march(ray, res.t0, res.t1);
 	}
 
 	gl_FragColor = vec4(color, 1.0);
 }
 
-vec3 sky(Ray ray)
-{
-	vec3 col1 = vec3(0.75, 0.78, 0.8);
-	vec3 col2 = vec3(0.56, 0.7, 1.0);
-
-	float t = max(ray.dir.y, -0.5);
-	return mix(col1, col2, t);
-}
-
 float eval(vec3 pos)
 {
 	vec3 tc = pos * 0.5 + 0.5;
+
+	if(tc.x < 0.0 || tc.y < 0.0 || tc.z < zclip || tc.x > 1.0 || tc.y > 1.0 || tc.z > 1.0) {
+		return 0.0;
+	}
+
 	return texture1D(xfer_tex, texture3D(volume, tc).x).x;
 }
 
-vec3 ray_march(Ray ray)
+#define OFFS	0.01
+vec3 ray_march(Ray ray, float t0, float t1)
 {
-	const float ray_step = 0.1;
 	float energy = 1.0;
-	vec3 pos = ray.origin;
-	float col = 0.0;
+	float t = t0;
+	vec3 col = vec3(0.0, 0.0, 0.0);
 
-	for(int i=0; i<40; i++) {
+
+	while(t < t1) {
+		vec3 pos = ray.origin + ray.dir * t;
+		t += ray_step;
+
 		float val = eval(pos) * energy;
-		col += val;
+		vec3 norm;
+
+		norm.x = eval(pos + vec3(OFFS, 0.0, 0.0)) - val;
+		norm.y = eval(pos + vec3(0.0, OFFS, 0.0)) - val;
+		norm.z = eval(pos + vec3(0.0, 0.0, OFFS)) - val;
+		norm = normalize(norm);
+
+		col += shade(ray, pos, norm) * val;
 		energy -= val;
 		if(energy < 0.001) {
 			break;
@@ -71,17 +79,17 @@
 		pos += ray.dir * ray_step;
 	}
 
-	return vec3(col, col, col);
+	return col;
 }
 
-vec3 shade(Ray ray, ISect isect)
+vec3 shade(Ray ray, vec3 pos, vec3 norm)
 {
-	vec3 ldir = normalize(vec3(10.0, 10.0, -10.0) - isect.pos);
+	vec3 ldir = normalize(vec3(10.0, 10.0, -10.0) - pos);
 	vec3 vdir = -ray.dir;
 	vec3 hdir = normalize(ldir + vdir);
 
-	float ndotl = dot(ldir, isect.normal);
-	float ndoth = dot(hdir, isect.normal);
+	float ndotl = dot(ldir, norm);
+	float ndoth = dot(hdir, norm);
 
 	vec3 dcol = vec3(1.0, 1.0, 1.0) * max(ndotl, 0.0);
 	vec3 scol = vec3(0.6, 0.6, 0.6) * pow(max(ndoth, 0.0), 50.0);
@@ -102,10 +110,10 @@
 {
 	ISect res;
 	res.hit = false;
+	res.t0 = res.t1 = 0.0;
 
 	if(ray.origin.x >= aabb.min.x && ray.origin.y >= aabb.min.y && ray.origin.z >= aabb.min.z &&
 			ray.origin.x < aabb.max.x && ray.origin.y < aabb.max.y && ray.origin.z < aabb.max.z) {
-		res.t = 0.0;
 		res.hit = true;
 		return res;
 	}
@@ -140,28 +148,9 @@
 		return res;
 	}
 
-	res.t = tmin;
+	res.t0 = tmin;
+	res.t1 = tmax;
 	res.hit = true;
-	res.pos = ray.origin + ray.dir * res.t;
-
-	/*if(res.pos.x > res.pos.y && res.pos.x > res.pos.z) {
-		res.normal = vec3(1.0, 0.0, 0.0);
-	} else if(res.pos.x < res.pos.y && res.pos.x < res.pos.z) {
-		res.normal = vec3(-1.0, 0.0, 0.0);
-	} else if(res.pos.y > res.pos.x && res.pos.y > res.pos.z) {
-		res.normal = vec3(0.0, 1.0, 0.0);
-	} else if(res.pos.y < res.pos.x && res.pos.y < res.pos.z) {
-		res.normal = vec3(0.0, -1.0, 0.0);
-	} else if(res.pos.z > res.pos.x && res.pos.z > res.pos.y) {
-		res.normal = vec3(0.0, 0.0, 1.0);
-	} else {
-		res.normal = vec3(0.0, 0.9, -1.0);
-	}
-	if(res.pos.x < 0.0) {
-		res.normal = vec3(1.0, 0.0, 0.0);
-	} else {
-		res.normal = vec3(0.0, 0.0, 1.0);
-	}*/
 	return res;
 }