1 files changed, 82 insertions, 0 deletions
diff --git a/src/font.rs b/src/font.rs
new file mode 100644
index 0000000..02d0a9f
--- /dev/null
+++ b/src/font.rs
@@ -0,0 +1,82 @@
+use crate::{context, texture, shader};
+
+const CHAR_WIDTH: i32 = 7;
+const CHAR_HEIGHT: i32 = 9;
+const FONT_WIDTH: i32 = 112;
+const FONT_HEIGHT: i32 = 54;
+
+pub struct Font {
+    pub shader: shader::Shader,
+    pub font: texture::Texture,
+}
+
+impl Font {
+    pub fn new(ctx: &context::Context) -> Self {
+        let shader = shader::Shader::new_nolib(
+            &ctx,
+            include_str!("assets/shaders/text/vert.glsl"),
+            include_str!("assets/shaders/text/frag.glsl"),
+        );
+        let font = texture::Texture::new(ctx, include_bytes!("assets/fonts/simple.png"));
+        Self {
+            shader,
+            font,
+        }
+    }
+
+    pub fn render_text(&self, ctx: &context::Context, pos: &glam::Vec2, text: &str) {
+        let mut width = 0;
+        let mut linewidth = 0;
+        let mut height = CHAR_HEIGHT;
+        for c in text.chars() {
+            if c == '\n' {
+                width = width.max(linewidth);
+                linewidth = 0;
+                height += CHAR_HEIGHT;
+            } else {
+                linewidth += CHAR_WIDTH; 
+            }
+        }
+        width = width.max(linewidth);
+
+        self.shader.bind(ctx);
+        let len = text.len().min(256);
+        self.shader.set_i32(ctx, "text_length", len as _);
+        let textvals: Vec<i32> = text.as_bytes().into_iter().take(len).map(|b| {
+            *b as i32
+        }).collect();
+        self.shader.set_i32_array(ctx, "text[0]", &textvals);
+        self.shader.set_i32(ctx, "char_width", CHAR_WIDTH as _);
+        self.shader.set_i32(ctx, "char_height", CHAR_HEIGHT as _);
+        self.shader.set_i32(ctx, "font_width", FONT_WIDTH as _);
+        self.shader.set_i32(ctx, "font_height", FONT_HEIGHT as _);
+        self.shader.set_i32(ctx, "text_width", width as _);
+        self.shader.set_i32(ctx, "text_height", height as _);
+        self.shader.set_mat4(
+            ctx, "view",
+            &glam::Mat4::from_scale(
+                glam::Vec3::new(
+                    2.0 / context::RENDER_WIDTH,
+                    2.0 / context::RENDER_HEIGHT,
+                    1.0,
+                ),
+            ),
+        );
+        let halfwidth = width as f32 / 2.0;
+        let halfheight = height as f32 / 2.0;
+        self.shader.set_mat4(
+            ctx, "position",
+            &glam::Mat4::from_scale_rotation_translation(
+                glam::Vec3::new(halfwidth, halfheight, 1.0),
+                glam::Quat::IDENTITY,
+                glam::Vec3::new(
+                    -context::RENDER_WIDTH / 2.0 + pos.x + halfwidth,
+                    context::RENDER_HEIGHT / 2.0 - pos.y - halfheight,
+                    0.0,
+                ),
+            )
+        );
+        self.font.bind(ctx);
+        ctx.render_no_geometry();
+    }
+}