test_tr.frag: trans flag on a ball and distorted. i have no idea

examples/test/project.toml

@@ -6,3 +6,8 @@ boot_scene = 0
 name = "test"
 vert = "shaders/quad.vert"
 frag = "shaders/test.frag"
+
+[[scene]]
+name = "test_tr"
+vert = "shaders/quad.vert"
+frag = "shaders/test_tr.frag"

examples/test/shaders/test_tr.frag

@@ -0,0 +1,114 @@
+#version 330 core
+
+#define FOV 8
+
+#define EPSILON 0.01
+#define MAX_STEPS 64
+#define NEAR_D 0.
+#define FAR_D 40.
+
+#define GRAD_EPSILON 0.0001
+
+#define saturate(x) clamp(x, 0, 1)
+
+uniform vec2 u_Resolution;
+uniform vec4 u_Mouse;
+uniform float u_Time;
+
+out vec4 color;
+
+#include "hg_sdf.glsl"
+#include "utils.glsl"
+#include "march_prolog.glsl"
+#include "colormap_cool.glsl"
+
+vec3 ray_dir(float fov, vec2 uv) {
+	float z = 1./tan(radians(fov)/2.);
+	return normalize(vec3(uv, z));
+}
+
+SceneResult scene_f(vec3 p) {
+	SceneResult box = SceneResult(fSphere(p, 2), 0.);
+
+	return box;
+}
+
+vec3 estimate_scene_normal(vec3 p) {
+	vec3 dx = vec3(GRAD_EPSILON, 0, 0);
+	vec3 dy = vec3(0, GRAD_EPSILON, 0);
+	vec3 dz = vec3(0, 0, GRAD_EPSILON);
+
+	return normalize(vec3(
+		scene_f(p + dx).d - scene_f(p - dx).d,
+		scene_f(p + dy).d - scene_f(p - dy).d,
+		scene_f(p + dz).d - scene_f(p - dz).d
+	));
+}
+
+vec3 raymarch(vec3 o, vec3 d, float start, float end) {
+	float t = start;
+	for (int i = 0; i < MAX_STEPS; i++) {
+		SceneResult sr = scene_f(o + d*t);
+		if (sr.d < EPSILON || t > end)
+			return vec3(t, sr.mat_idx, i);
+
+		t += sr.d;
+	}
+	return vec3(end, N_HIT_FAR_PLANE, MAX_STEPS);
+}
+
+vec4 flag(float p) {
+	p = abs(p);
+	if (p < 0.167) {
+		return vec4(1);
+	} else if (p < 0.5) {
+		return vec4(0.960784, 0.662745, 0.721569, 1);
+	} else {
+		return vec4(0.356863, 0.807843, 0.980392, 1);
+	}
+}
+
+vec4 shade_material(vec3 p, vec3 norm, float mat_idx) {
+	if (mat_idx == 0.) {
+		return flag(p.y/(sin(p.z)+1));
+	}
+}
+
+vec4 shade(vec3 p, float mat_idx) {
+	vec3 norm = estimate_scene_normal(p);
+	vec4 color_mat = shade_material(p, norm, mat_idx);
+
+	return color_mat;
+}
+
+void main() {
+	vec2 mouse_uv = u_Mouse.xy * 2.0 / u_Resolution.xy - 1.0;
+
+	vec2 uv = gl_FragCoord.xy * 2.0 / u_Resolution.xy - 1.0;
+	uv.x *= u_Resolution.x/u_Resolution.y;
+
+    float an = 0.3 * u_Time;
+    float d = 6.;
+	vec3 eye = vec3(3. * sin(an), 2., 3. * cos(an)) * d;
+	vec3 target = vec3(0., 0., 0.);
+	mat3 lookAt = look_mat(eye, target, 0);
+	vec3 dir = normalize(lookAt * ray_dir(FOV, uv));
+
+	color = vec4(0.);
+
+	vec3 result = raymarch(eye, dir, NEAR_D, FAR_D);
+	float depth = result.x;
+	float mat_idx = result.y;
+	float iters = result.z;
+	if (depth >= FAR_D) {
+		color = vec4(0.);
+		return;
+	}
+
+	vec3 p = eye + dir * depth; // recast the ray
+	color = shade(p, mat_idx);
+
+    // gamma
+    color = vec4(pow(clamp(color.xyz, 0.0, 1.0), vec3(0.4545)), 1.0);
+}
+