feat(engine): add ability to render triangles

1 files changed, 198 insertions, 0 deletions

diff --git a/engine/src/shader.rs b/engine/src/shader.rs
new file mode 100644
index 0000000..0bbca77
--- /dev/null
+++ b/engine/src/shader.rs
@@ -0,0 +1,198 @@
+use std::ffi::CStr;
+use std::ptr::null_mut;
+
+#[derive(Debug)]
+pub struct Shader
+{
+    shader: gl::types::GLuint,
+}
+
+impl Shader
+{
+    pub fn new(kind: Kind) -> Self
+    {
+        let shader = unsafe { gl::CreateShader(kind.into_gl()) };
+
+        Self { shader }
+    }
+
+    pub fn set_source(&self, source: &str) -> Result<(), Error>
+    {
+        if !source.is_ascii() {
+            return Err(Error::SourceNotAscii);
+        }
+
+        unsafe {
+            #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+            gl::ShaderSource(
+                self.shader,
+                1,
+                &source.as_ptr().cast(),
+                &(source.len() as gl::types::GLint),
+            );
+        }
+
+        Ok(())
+    }
+
+    pub fn compile(&self) -> Result<(), Error>
+    {
+        unsafe {
+            gl::CompileShader(self.shader);
+        }
+
+        let mut compile_success = gl::types::GLint::default();
+
+        unsafe {
+            gl::GetShaderiv(self.shader, gl::COMPILE_STATUS, &mut compile_success);
+        }
+
+        if compile_success == 0 {
+            let info_log = self.get_info_log();
+
+            return Err(Error::CompileFailed(info_log));
+        }
+
+        Ok(())
+    }
+
+    fn get_info_log(&self) -> String
+    {
+        let mut buf = vec![gl::types::GLchar::default(); 512];
+
+        unsafe {
+            #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+            gl::GetShaderInfoLog(
+                self.shader,
+                buf.len() as gl::types::GLsizei,
+                null_mut(),
+                buf.as_mut_ptr(),
+            );
+        }
+
+        let info_log = unsafe { CStr::from_ptr(buf.as_ptr()) };
+
+        unsafe { String::from_utf8_unchecked(info_log.to_bytes().to_vec()) }
+    }
+}
+
+impl Drop for Shader
+{
+    fn drop(&mut self)
+    {
+        unsafe {
+            gl::DeleteShader(self.shader);
+        }
+    }
+}
+
+/// Shader kind.
+#[derive(Debug, Clone, Copy)]
+pub enum Kind
+{
+    Vertex,
+    Fragment,
+}
+
+impl Kind
+{
+    fn into_gl(self) -> gl::types::GLenum
+    {
+        match self {
+            Self::Vertex => gl::VERTEX_SHADER,
+            Self::Fragment => gl::FRAGMENT_SHADER,
+        }
+    }
+}
+
+/// Shader program
+#[derive(Debug)]
+pub struct Program
+{
+    program: gl::types::GLuint,
+}
+
+impl Program
+{
+    pub fn new() -> Self
+    {
+        let program = unsafe { gl::CreateProgram() };
+
+        Self { program }
+    }
+
+    pub fn attach(&self, shader: &Shader)
+    {
+        unsafe {
+            gl::AttachShader(self.program, shader.shader);
+        }
+    }
+
+    pub fn link(&self) -> Result<(), Error>
+    {
+        unsafe {
+            gl::LinkProgram(self.program);
+        }
+
+        let mut link_success = gl::types::GLint::default();
+
+        unsafe {
+            gl::GetProgramiv(self.program, gl::LINK_STATUS, &mut link_success);
+        }
+
+        if link_success == 0 {
+            let info_log = self.get_info_log();
+
+            return Err(Error::CompileFailed(info_log));
+        }
+
+        Ok(())
+    }
+
+    pub fn activate(&self)
+    {
+        unsafe {
+            gl::UseProgram(self.program);
+        }
+    }
+
+    fn get_info_log(&self) -> String
+    {
+        let mut buf = vec![gl::types::GLchar::default(); 512];
+
+        unsafe {
+            #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+            gl::GetProgramInfoLog(
+                self.program,
+                buf.len() as gl::types::GLsizei,
+                null_mut(),
+                buf.as_mut_ptr(),
+            );
+        }
+
+        let info_log = unsafe { CStr::from_ptr(buf.as_ptr()) };
+
+        unsafe { String::from_utf8_unchecked(info_log.to_bytes().to_vec()) }
+    }
+}
+
+impl Drop for Program
+{
+    fn drop(&mut self)
+    {
+        unsafe {
+            gl::DeleteProgram(self.program);
+        }
+    }
+}
+
+/// Shader error.
+#[derive(Debug, thiserror::Error)]
+pub enum Error
+{
+    #[error("All characters in source are not within the ASCII range")]
+    SourceNotAscii,
+
+    #[error("Failed to compile: {0}")]
+    CompileFailed(String),
+}