graphics: optional color render pass color attachment

not-fl3 · Nov 1, 2023 · f9899b5 · f9899b5
1 parent aa38a5b
commit f9899b5
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Showing 3 changed files with 36 additions and 19 deletions.
diff --git a/src/graphics.rs b/src/graphics.rs
@@ -1156,9 +1156,13 @@ pub trait RenderingBackend {
         height: i32,
         bytes: &[u8],
     );
-    fn new_render_pass(&mut self, color_img: TextureId, depth_img: Option<TextureId>)
-        -> RenderPass;
-    fn render_pass_texture(&self, render_pass: RenderPass) -> TextureId;
+    fn new_render_pass(
+        &mut self,
+        color_img: Option<TextureId>,
+        depth_img: Option<TextureId>,
+    ) -> RenderPass;
+    /// for depth-only render pass returns None
+    fn render_pass_texture(&self, render_pass: RenderPass) -> Option<TextureId>;
     fn delete_render_pass(&mut self, render_pass: RenderPass);
     fn new_pipeline(
         &mut self,

diff --git a/src/graphics/gl.rs b/src/graphics/gl.rs
@@ -422,7 +422,7 @@ fn get_uniform_location(program: GLuint, name: &str) -> Option<i32> {
 
 pub(crate) struct RenderPassInternal {
     gl_fb: GLuint,
-    texture: TextureId,
+    texture: Option<TextureId>,
     depth_texture: Option<TextureId>,
 }
 
@@ -912,21 +912,26 @@ impl RenderingBackend for GlContext {
 
     fn new_render_pass(
         &mut self,
-        color_img: TextureId,
+        color_img: Option<TextureId>,
         depth_img: Option<TextureId>,
     ) -> RenderPass {
+        if color_img.is_none() && depth_img.is_none() {
+            panic!("Render pass should have at least one non-none target");
+        }
         let mut gl_fb = 0;
 
         unsafe {
             glGenFramebuffers(1, &mut gl_fb as *mut _);
             glBindFramebuffer(GL_FRAMEBUFFER, gl_fb);
-            glFramebufferTexture2D(
-                GL_FRAMEBUFFER,
-                GL_COLOR_ATTACHMENT0,
-                GL_TEXTURE_2D,
-                self.textures.get(color_img).raw,
-                0,
-            );
+            if let Some(color_img) = color_img {
+                glFramebufferTexture2D(
+                    GL_FRAMEBUFFER,
+                    GL_COLOR_ATTACHMENT0,
+                    GL_TEXTURE_2D,
+                    self.textures.get(color_img).raw,
+                    0,
+                );
+            }
             if let Some(depth_img) = depth_img {
                 glFramebufferTexture2D(
                     GL_FRAMEBUFFER,
@@ -948,15 +953,18 @@ impl RenderingBackend for GlContext {
 
         RenderPass(self.passes.len() - 1)
     }
-    fn render_pass_texture(&self, render_pass: RenderPass) -> TextureId {
+    // for depth-only render pass will return None
+    fn render_pass_texture(&self, render_pass: RenderPass) -> Option<TextureId> {
         self.passes[render_pass.0].texture
     }
     fn delete_render_pass(&mut self, render_pass: RenderPass) {
         let render_pass = &mut self.passes[render_pass.0];
 
         unsafe { glDeleteFramebuffers(1, &mut render_pass.gl_fb as *mut _) }
 
-        self.textures.get(render_pass.texture).delete();
+        if let Some(color_texture) = render_pass.texture {
+            self.textures.get(color_texture).delete();
+        }
         if let Some(depth_texture) = render_pass.depth_texture {
             self.textures.get(depth_texture).delete();
         }
@@ -1416,10 +1424,13 @@ impl RenderingBackend for GlContext {
             }
             Some(pass) => {
                 let pass = &self.passes[pass.0];
+                // new_render_pass will panic with both color and depth components none
+                // so unwrap is safe here
+                let texture = pass.texture.or(pass.depth_texture).unwrap();
                 (
                     pass.gl_fb,
-                    self.textures.get(pass.texture).params.width as i32,
-                    self.textures.get(pass.texture).params.height as i32,
+                    self.textures.get(texture).params.width as i32,
+                    self.textures.get(texture).params.height as i32,
                 )
             }
         };

diff --git a/src/graphics/metal.rs b/src/graphics/metal.rs
@@ -531,9 +531,11 @@ impl RenderingBackend for MetalContext {
 
     fn new_render_pass(
         &mut self,
-        color_img: TextureId,
+        color_img: Option<TextureId>,
         depth_img: Option<TextureId>,
     ) -> RenderPass {
+        let color_img = color_img.expect("color_img: None not yet implemented");
+
         unsafe {
             let render_pass_desc =
                 msg_send_![class!(MTLRenderPassDescriptor), renderPassDescriptor];
@@ -576,8 +578,8 @@ impl RenderingBackend for MetalContext {
         }
     }
 
-    fn render_pass_texture(&self, render_pass: RenderPass) -> TextureId {
-        self.passes[render_pass.0].texture
+    fn render_pass_texture(&self, render_pass: RenderPass) -> Option<TextureId> {
+        Some(self.passes[render_pass.0].texture)
     }
 
     fn new_buffer(&mut self, _: BufferType, _usage: BufferUsage, data: BufferSource) -> BufferId {