From e246f90bc33fd489e300366e30354e34a05b8107 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Sun, 3 Mar 2024 22:33:53 +0100
Subject: feat(engine): create shader programs when needed

---
 engine/src/lib.rs          |  7 -----
 engine/src/renderer/mod.rs | 66 +++++++++++++++++++++-------------------------
 2 files changed, 30 insertions(+), 43 deletions(-)

(limited to 'engine')

diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index e39f1c6..332a011 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -141,10 +141,6 @@ where
     /// Will return `Err` if updating the window fails.
     pub fn start(&mut self, mut func: impl FnMut(&mut Self)) -> Result<(), Error>
     {
-        self.renderer
-            .create_shader_programs(self.objects.values().map(Object::shader))
-            .map_err(Error::ShaderCreationFailed)?;
-
         let mut prev_frame_start: Option<Instant> = None;
 
         while !self.window.should_close() {
@@ -293,9 +289,6 @@ pub enum Error
 
     #[error("Rendering failed")]
     RenderingFailed(#[source] renderer::Error),
-
-    #[error("Failed to create shaders")]
-    ShaderCreationFailed(#[source] renderer::Error),
 }
 
 #[derive(Debug)]
diff --git a/engine/src/renderer/mod.rs b/engine/src/renderer/mod.rs
index 6c04323..839c0d3 100644
--- a/engine/src/renderer/mod.rs
+++ b/engine/src/renderer/mod.rs
@@ -83,40 +83,6 @@ where
         })
     }
 
-    pub fn create_shader_programs<'program>(
-        &mut self,
-        programs: impl IntoIterator<Item = &'program ShaderProgram>,
-    ) -> Result<(), Error>
-    {
-        for program in programs {
-            let gl_shaders = program
-                .shaders()
-                .iter()
-                .map(|shader| {
-                    let gl_shader = GlShader::new(shader.kind());
-
-                    gl_shader.set_source(shader.source())?;
-                    gl_shader.compile()?;
-
-                    Ok::<_, Error>(gl_shader)
-                })
-                .collect::<Result<Vec<_>, _>>()?;
-
-            let gl_shader_program = GlShaderProgram::new();
-
-            for gl_shader in &gl_shaders {
-                gl_shader_program.attach(gl_shader);
-            }
-
-            gl_shader_program.link()?;
-
-            self.shader_programs
-                .insert(program.u64_hash(), gl_shader_program);
-        }
-
-        Ok(())
-    }
-
     pub fn render<'obj>(
         &mut self,
         objects: impl IntoIterator<Item = &'obj Object>,
@@ -129,8 +95,8 @@ where
         for obj in objects {
             let shader_program = self
                 .shader_programs
-                .get(&obj.shader().u64_hash())
-                .ok_or(Error::MissingShaderProgram)?;
+                .entry(obj.shader().u64_hash())
+                .or_insert_with(|| create_gl_shader_program(obj.shader()).unwrap());
 
             shader_program.activate(|shader_program_curr_bound| {
                 apply_transformation_matrices(
@@ -249,6 +215,34 @@ fn create_gl_texture(texture: &Texture) -> GlTexture
     gl_texture
 }
 
+fn create_gl_shader_program(
+    shader_program: &ShaderProgram,
+) -> Result<GlShaderProgram, GlShaderError>
+{
+    let gl_shaders = shader_program
+        .shaders()
+        .iter()
+        .map(|shader| {
+            let gl_shader = GlShader::new(shader.kind());
+
+            gl_shader.set_source(shader.source())?;
+            gl_shader.compile()?;
+
+            Ok(gl_shader)
+        })
+        .collect::<Result<Vec<_>, _>>()?;
+
+    let gl_shader_program = GlShaderProgram::new();
+
+    for gl_shader in &gl_shaders {
+        gl_shader_program.attach(gl_shader);
+    }
+
+    gl_shader_program.link()?;
+
+    Ok(gl_shader_program)
+}
+
 #[derive(Debug)]
 pub struct Renderable
 {
-- 
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