From c0089dd0567b8d6538360a21f042cbb0913fff99 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Sat, 30 Jan 2021 20:54:41 -0300
Subject: Output better error messages for shader programs

---
 src/lib.rs | 61 +++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 33 insertions(+), 28 deletions(-)

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
index 218d5b4..4662f08 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,29 +16,6 @@ pub struct Bezier {
     pub dpy: Poly,
 }
 
-pub fn to_poly(v: &Vec<f32>) -> Poly {
-    match v.len() {
-        0 => Poly::new(vec![0.0]),
-        1 => Poly::new(vec![v[0]]),
-        2 => Poly::new(vec![v[0], v[1] - v[0]]),
-        _ => {
-            let mut pv = Vec::new();
-            for i in 0..v.len() - 1 {
-                pv.push(Poly::new(vec![v[i], v[i + 1] - v[i]]));
-            }
-            while pv.len() > 1 {
-                let mut npv = Vec::new();
-                for i in 0..pv.len() - 1 {
-                    let c = &pv[i + 1] - &pv[i];
-                    npv.push(&pv[i] + &c.shift());
-                }
-                pv = npv;
-            }
-            pv[0].clone()
-        }
-    }
-}
-
 impl Bezier {
     pub fn new() -> Bezier {
         Bezier {
@@ -169,10 +146,9 @@ impl Bezier {
         float inside(vec2 pos) {{
           float closest = inf;
           float t = 0.0;
-          float dstep = 0.0;
-          while (t < 1.0 - dstep) {{
-            dstep = step_size / length(vec2(eval_dpx(t), eval_dpy(t)));
-            float step = t + dstep;
+          while (t < 1.0) {{
+            float dstep = step_size / length(vec2(eval_dpx(t), eval_dpy(t)));
+            float step = min(t + dstep, 1.0);
             vec2 a = vec2(eval_px(t), eval_py(t));
             vec2 b = vec2(eval_px(step), eval_py(step));
             float c = pow(length(a - b), 2);
@@ -226,6 +202,29 @@ impl Bezier {
     }
 }
 
+fn to_poly(v: &Vec<f32>) -> Poly {
+    match v.len() {
+        0 => Poly::new(vec![0.0]),
+        1 => Poly::new(vec![v[0]]),
+        2 => Poly::new(vec![v[0], v[1] - v[0]]),
+        _ => {
+            let mut pv = Vec::new();
+            for i in 0..v.len() - 1 {
+                pv.push(Poly::new(vec![v[i], v[i + 1] - v[i]]));
+            }
+            while pv.len() > 1 {
+                let mut npv = Vec::new();
+                for i in 0..pv.len() - 1 {
+                    let c = &pv[i + 1] - &pv[i];
+                    npv.push(&pv[i] + &c.shift());
+                }
+                pv = npv;
+            }
+            pv[0].clone()
+        }
+    }
+}
+
 fn shader_from_source(source: &CStr, shader_type: GLenum) -> GLuint {
     unsafe {
         let shader: GLuint = gl::CreateShader(shader_type);
@@ -234,7 +233,13 @@ fn shader_from_source(source: &CStr, shader_type: GLenum) -> GLuint {
         let mut success: gl::types::GLint = 1;
         gl::GetShaderiv(shader, gl::COMPILE_STATUS, &mut success);
         if success == 0 {
-            println!("Compilation error: {}", source.to_str().unwrap());
+            let mut length: GLint = 0;
+            gl::GetShaderiv(shader, gl::INFO_LOG_LENGTH, &mut length);
+            let mut buffer: Vec<u8> = Vec::with_capacity(length as usize + 1);
+            buffer.extend([b' '].iter().cycle().take(length as usize));
+            let error: CString = CString::from_vec_unchecked(buffer);
+            gl::GetShaderInfoLog(shader, length, std::ptr::null_mut(), error.as_ptr() as *mut GLchar);
+            println!("Compilation error: {}", error.to_str().unwrap());
         }
         shader
     }
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