Fix curve overextending past last control point

1 files changed, 43 insertions, 25 deletions

diff --git a/src/main.rs b/src/main.rs
index ee508e1..2c5dbcc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,4 @@
-mod lerp;
-mod poly;
-
-use lerp::Lerp;
-use poly::Poly;
+use bezier::Bezier;
 
 use std::ffi::{CStr, CString};
 
@@ -25,7 +21,7 @@ fn shader_from_source(source: &CStr, shader_type: GLenum) -> GLuint {
     }
 }
 
-fn compile_bezier_shader(a: Poly, b: Poly) -> GLuint {
+fn compile_bezier_shader(c: Bezier) -> GLuint {
     let vertex_shader_source = b"
     #version 410 core
     layout (location = 0) in vec3 aPos;
@@ -41,34 +37,48 @@ fn compile_bezier_shader(a: Poly, b: Poly) -> GLuint {
     #version 410 core
     out vec4 FragColor;
 
-    float pa[{sa}] = float[{sa}]({pa});
-    float pb[{sb}] = float[{sb}]({pb});
+    float inf = 1000000;
+    float vx[{s}] = float[{s}]({vx});
+    float vy[{s}] = float[{s}]({vy});
+    float px[{sx}] = float[{sx}]({px});
+    float py[{sy}] = float[{sy}]({py});
+    float thr = 32;
 
-    float eval_a(float[{sa}] v, float t) {{
+    float eval_a(float[{sx}] v, float t) {{
         float result = 0.0;
-        for (int i = 0; i < {sa}; i++) {{
+        for (int i = 0; i < {sx}; i++) {{
           result += v[i] * pow(t, i);
         }}
         return result;
     }}
 
-    float eval_b(float[{sb}] v, float t) {{
+    float eval_b(float[{sy}] v, float t) {{
         float result = 0.0;
-        for (int i = 0; i < {sb}; i++) {{
+        for (int i = 0; i < {sy}; i++) {{
           result += v[i] * pow(t, i);
         }}
         return result;
     }}
 
+    float control(vec2 pos) {{
+      float closest = inf;
+      for (int i = 0; i < {s}; i++) {{
+        float d = distance(pos, vec2(vx[i], vy[i]));
+        if (d < closest) {{
+          closest = d;
+        }}
+      }}
+      return 1 - closest / thr;
+    }}
+
     float inside(vec2 pos) {{
       float res = 100;
-      float thr = 32;
-      float closest = 1000000;
+      float closest = inf;
       float t = 0.0;
-      while (t < 1.0) {{
+      while (t < 1.0 - 1.0 / res) {{
         float step = t + 1.0 / res;
-        vec2 a = vec2(eval_a(pa, t), eval_b(pb, t));
-        vec2 b = vec2(eval_a(pa, step), eval_b(pb, step));
+        vec2 a = vec2(eval_a(px, t), eval_b(py, t));
+        vec2 b = vec2(eval_a(px, step), eval_b(py, step));
         float c = pow(length(a - b), 2);
         float d = distance(pos, a + clamp(dot(pos - a, b - a) / c, 0, 1) * (b - a));
         if (d < closest) {{
@@ -81,13 +91,17 @@ fn compile_bezier_shader(a: Poly, b: Poly) -> GLuint {
 
     void main() {{
       float r = inside(gl_FragCoord.xy);
-        FragColor = vec4(r * 0.8, r * 0.2, r, 1.0);
+      float c = control(gl_FragCoord.xy);
+      FragColor = vec4(r, c, 0.0, 1.0);
     }}
     ",
-        sa = a.degree() + 1,
-        sb = b.degree() + 1,
-        pa = &a,
-        pb = &b
+        sx = c.px.degree() + 1,
+        sy = c.py.degree() + 1,
+        px = &c.px,
+        py = &c.py,
+        s  = c.degree,
+        vx = c.show_x(),
+        vy = c.show_y(),
     )
     .into_bytes();
 
@@ -112,8 +126,12 @@ fn compile_bezier_shader(a: Poly, b: Poly) -> GLuint {
 }
 
 fn main() {
-    let a = Lerp::new(vec![200.0, 500.0, 500.0]).to_poly();
-    let b = Lerp::new(vec![200.0, 500.0, 200.0]).to_poly();
+    let mut curve = Bezier::new();
+    curve.push(200, 200);
+    curve.push(300, 800);
+    curve.push(800, 100);
+    curve.push(1300, 800);
+    curve.push(1400, 200);
 
     let sdl_context = sdl2::init().unwrap();
     let video_subsystem = sdl_context.video().unwrap();
@@ -167,7 +185,7 @@ fn main() {
         gl::EnableVertexAttribArray(0);
     }
 
-    let shader_program = compile_bezier_shader(a, b);
+    let shader_program = compile_bezier_shader(curve);
 
     let mut event_pump = sdl_context.event_pump().unwrap();
     'running: loop {