# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1333378786 -10800
# Node ID 3e53a16d4667f37ff4a71ea808084ef27bc52af5
# Parent  6f275934717b38154279218f1e52e028947b5053
foo

diff -r 6f275934717b -r 3e53a16d4667 src/volray.c
--- a/src/volray.c	Mon Apr 02 14:42:03 2012 +0300
+++ b/src/volray.c	Mon Apr 02 17:59:46 2012 +0300
@@ -22,8 +22,11 @@
 
 int init(void);
 void disp(void);
+void render_volume(void);
+void draw_xfer_func(void);
 void reshape(int x, int y);
 void keyb(unsigned char key, int x, int y);
+void keyb_up(unsigned char key, int x, int y);
 void mouse(int bn, int state, int x, int y);
 void motion(int x, int y);
 int parse_args(int argc, char **argv);
@@ -47,6 +50,8 @@
 float xfer_mean = 0.5, xfer_sdev = 1.0;
 int xfertex_needs_recalc = 1;
 
+static int uimode_xfer;
+
 int main(int argc, char **argv)
 {
 	glutInit(&argc, argv);
@@ -62,6 +67,7 @@
 	glutDisplayFunc(disp);
 	glutReshapeFunc(reshape);
 	glutKeyboardFunc(keyb);
+	glutKeyboardUpFunc(keyb_up);
 	glutMouseFunc(mouse);
 	glutMotionFunc(motion);
 
@@ -90,9 +96,9 @@
 	glBindTexture(GL_TEXTURE_3D, vol_tex);
 	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP);
-	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP);
-	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP);
+	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	for(i=0; i<nslices; i++) {
 		int xsz, ysz;
@@ -130,14 +136,27 @@
 
 void disp(void)
 {
+	/* recalculate primary ray texture if needed */
 	if(raytex_needs_recalc) {
 		create_ray_texture(win_xsz, win_ysz, 50.0, &tex_scale);
 	}
+	/* recalculate transfer function texture if needed */
 	if(xfertex_needs_recalc) {
 		create_transfer_map(xfer_mean, xfer_sdev);
 	}
 
+	render_volume();
+	draw_xfer_func();
+
+	glutSwapBuffers();
+	assert(glGetError() == GL_NO_ERROR);
+}
+
+void render_volume(void)
+{
+	/* set the camera transformation */
 	glMatrixMode(GL_MODELVIEW);
+	glPushMatrix();
 	glLoadIdentity();
 	glRotatef(-90, 1, 0, 0);
 	glTranslatef(cam_x, cam_y, -cam_z);
@@ -145,18 +164,23 @@
 	glRotatef(cam_phi, 1, 0, 0);
 	glTranslatef(0, 0, -cam_dist);
 
+	/* setup the texture matrix to map the useful part of the ray texture to [0,1] */
 	glMatrixMode(GL_TEXTURE);
+	glPushMatrix();
 	glLoadIdentity();
 	glScalef(tex_scale.x, tex_scale.y, 1.0);
 
+	/* tex unit0: volume data 3D texture */
 	glActiveTexture(GL_TEXTURE0);
 	glBindTexture(GL_TEXTURE_3D, vol_tex);
 	glEnable(GL_TEXTURE_3D);
 
+	/* tex unit1: primary rays in view space */
 	glActiveTexture(GL_TEXTURE1);
 	glBindTexture(GL_TEXTURE_2D, ray_tex);
 	glEnable(GL_TEXTURE_2D);
 
+	/* tex unit2: transfer function (1d) */
 	glActiveTexture(GL_TEXTURE2);
 	glBindTexture(GL_TEXTURE_1D, xfer_tex);
 	glEnable(GL_TEXTURE_1D);
@@ -179,15 +203,47 @@
 	glDisable(GL_TEXTURE_3D);
 
 	glMatrixMode(GL_TEXTURE);
-	glLoadIdentity();
+	glPopMatrix();
+	glMatrixMode(GL_MODELVIEW);
+	glPopMatrix();
+}
 
-	glutSwapBuffers();
-	assert(glGetError() == GL_NO_ERROR);
+void draw_xfer_func(void)
+{
+	glMatrixMode(GL_MODELVIEW);
+	glPushMatrix();
+	glTranslatef(-0.9, -0.9, 0);
+	glScalef(0.5, 0.1, 1);
+
+	glBindTexture(GL_TEXTURE_1D, xfer_tex);
+	glEnable(GL_TEXTURE_1D);
+
+	glBegin(GL_QUADS);
+	glColor3f(1, 1, 1);
+	glTexCoord1f(1);
+	glVertex2f(1, 0);
+	glVertex2f(1, 1);
+	glTexCoord1f(0);
+	glVertex2f(0, 1);
+	glVertex2f(0, 0);
+	glEnd();
+
+	glDisable(GL_TEXTURE_1D);
+
+	glLineWidth(2.0);
+	glBegin(GL_LINE_LOOP);
+	glColor3f(uimode_xfer ? 1 : 0, 0, uimode_xfer ? 0 : 1);
+	glVertex2f(0, 0);
+	glVertex2f(1, 0);
+	glVertex2f(1, 1);
+	glVertex2f(0, 1);
+	glEnd();
+
+	glPopMatrix();
 }
 
 void reshape(int x, int y)
 {
-	printf("reshape: %dx%d\n", x, y);
 	glViewport(0, 0, x, y);
 
 	if(x != win_xsz || y != win_ysz) {
@@ -202,6 +258,21 @@
 	switch(key) {
 	case 27:
 		exit(0);
+
+	case 'x':
+		uimode_xfer = 1;
+		glutPostRedisplay();
+		break;
+	}
+}
+
+void keyb_up(unsigned char key, int x, int y)
+{
+	switch(key) {
+	case 'x':
+		uimode_xfer = 0;
+		glutPostRedisplay();
+		break;
 	}
 }
 
@@ -219,30 +290,43 @@
 {
 	int dx = x - prev_x;
 	int dy = y - prev_y;
-
 	prev_x = x;
 	prev_y = y;
 
-	if(bnstate[0]) {
-		cam_theta += dx * 0.5;
-		cam_phi += dy * 0.5;
+	if(uimode_xfer) {
+		if(dx || dy) {
+			xfer_mean += dx / (float)win_xsz;
+			xfer_sdev += 0.5 * dy / (float)win_ysz;
 
-		if(cam_phi <= -90) cam_phi = -89;
-		if(cam_phi >= 90) cam_phi = 89;
+			xfer_mean = xfer_mean < 0.0 ? 0.0 : (xfer_mean > 1.0 ? 1.0 : xfer_mean);
+			xfer_sdev = xfer_sdev < 0.0 ? 0.0 : (xfer_sdev > 1.0 ? 1.0 : xfer_sdev);
 
-		glutPostRedisplay();
-	}
+			xfertex_needs_recalc = 1;
+			glutPostRedisplay();
+		}
+	} else {
 
-	if(bnstate[1]) {
-		cam_x += dx * 0.025;
-		cam_y += dy * 0.025;
-		glutPostRedisplay();
-	}
+		if(bnstate[0]) {
+			cam_theta += dx * 0.5;
+			cam_phi += dy * 0.5;
 
-	if(bnstate[2]) {
-		cam_dist += dy * 0.025;
-		if(cam_dist < 0.0) cam_dist = 0.0;
-		glutPostRedisplay();
+			if(cam_phi <= -90) cam_phi = -89;
+			if(cam_phi >= 90) cam_phi = 89;
+
+			glutPostRedisplay();
+		}
+
+		if(bnstate[1]) {
+			cam_x += dx * 0.025;
+			cam_y += dy * 0.025;
+			glutPostRedisplay();
+		}
+
+		if(bnstate[2]) {
+			cam_dist += dy * 0.025;
+			if(cam_dist < 0.0) cam_dist = 0.0;
+			glutPostRedisplay();
+		}
 	}
 }
 
@@ -264,10 +348,10 @@
 				}
 				break;
 
-			case 'v':
+			case 'd':
 				xfer_sdev = strtod(argv[++i], &endp);
 				if(endp == argv[i]) {
-					fprintf(stderr, "-v must be followed by the transfer function sdeviance\n");
+					fprintf(stderr, "-d must be followed by the transfer function std.deviation\n");
 					return -1;
 				}
 				break;
@@ -396,10 +480,11 @@
 	}
 
 	for(i=0; i<XFER_MAP_SZ; i++) {
-		float x = (float)i / (float)XFER_MAP_SZ;
-		map[i] = gaussian(x, mean, sdev);
+		float x = (float)i / (float)(XFER_MAP_SZ - 1);
+		map[i] = gaussian(x, mean, sdev) - 1.0;
 	}
+	putchar('\n');
 
-	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, XFER_MAP_SZ, 1, GL_LUMINANCE, GL_FLOAT, map);
+	glTexSubImage1D(GL_TEXTURE_1D, 0, 0, XFER_MAP_SZ, GL_LUMINANCE, GL_FLOAT, map);
 	xfertex_needs_recalc = 0;
 }
diff -r 6f275934717b -r 3e53a16d4667 volray.p.glsl
--- a/volray.p.glsl	Mon Apr 02 14:42:03 2012 +0300
+++ b/volray.p.glsl	Mon Apr 02 17:59:46 2012 +0300
@@ -1,10 +1,15 @@
 uniform sampler3D volume;
 uniform sampler2D ray_tex;
+uniform sampler1D xfer_tex;
 
 struct Ray {
 	vec3 origin, dir;
 };
 
+struct AABBox {
+	vec3 min, max;
+};
+
 struct ISect {
 	bool hit;
 	float t;
@@ -16,13 +21,22 @@
 vec3 ray_march(Ray ray);
 vec3 shade(Ray ray, ISect isect);
 Ray get_primary_ray();
+bool intersect_aabb(Ray ray, AABBox aabb, out float t);
 
 void main()
 {
+	const AABBox aabb = AABBox(vec3(0.0, 0.0, 0.0), vec3(1.0, 1.0, 1.0));
 	Ray ray = get_primary_ray();
 
-	gl_FragColor = vec4(ray_march(ray), 1.0);
-	//gl_FragColor = vec4(sky(ray), 1.0);
+	vec3 color = vec3(0.0, 0.0, 0.0);
+
+	float start_t;
+	if(intersect_aabb(ray, aabb, start_t)) {
+		ray.origin += ray.dir * start_t;
+		color = vec3(1.0, 0.0, 0.0);//ray_march(ray);
+	}
+
+	gl_FragColor = vec4(color, 1.0);
 }
 
 vec3 sky(Ray ray)
@@ -34,6 +48,11 @@
 	return mix(col1, col2, t);
 }
 
+float eval(vec3 pos)
+{
+	return texture1D(xfer_tex, texture3D(volume, pos).x).x;
+}
+
 vec3 ray_march(Ray ray)
 {
 	const float ray_step = 0.1;
@@ -42,8 +61,7 @@
 	float col = 0.0;
 
 	for(int i=0; i<40; i++) {
-		float val = texture3D(volume, pos).x;
-		val *= energy;
+		float val = eval(pos) * energy;
 		col += val;
 		energy -= val;
 		if(energy < 0.001) {
@@ -78,3 +96,45 @@
 	ray.origin = (gl_ModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0)).xyz;
 	return ray;
 }
+
+bool intersect_aabb(Ray ray, AABBox aabb, out float t)
+{
+	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) {
+		return true;
+	}
+
+	vec4 bbox[2];
+	bbox[0] = vec4(aabb.min.x, aabb.min.y, aabb.min.z, 0);
+	bbox[1] = vec4(aabb.max.x, aabb.max.y, aabb.max.z, 0);
+
+	int xsign = int(ray.dir.x < 0.0);
+	float invdirx = 1.0 / ray.dir.x;
+	float tmin = (bbox[xsign].x - ray.origin.x) * invdirx;
+	float tmax = (bbox[1 - xsign].x - ray.origin.x) * invdirx;
+
+	int ysign = int(ray.dir.y < 0.0);
+	float invdiry = 1.0 / ray.dir.y;
+	float tymin = (bbox[ysign].y - ray.origin.y) * invdiry;
+	float tymax = (bbox[1 - ysign].y - ray.origin.y) * invdiry;
+
+	if(tmin > tymax || tymin > tmax) {
+		return false;
+	}
+
+	if(tymin > tmin) tmin = tymin;
+	if(tymax < tmax) tmax = tymax;
+
+	int zsign = int(ray.dir.z < 0.0);
+	float invdirz = 1.0 / ray.dir.z;
+	float tzmin = (bbox[zsign].z - ray.origin.z) * invdirz;
+	float tzmax = (bbox[1 - zsign].z - ray.origin.z) * invdirz;
+
+	if(tmin > tzmax || tzmin > tmax) {
+		return false;
+	}
+
+	t = tmin;
+	return tmin < 1.0 && tmax > 0.0;
+}
+