Move readback format mapping to renderer gl

src/renderer_gl/opengl_capabilities.cpp

@@ -123,6 +123,32 @@ OpenGlPixelFormat texture_format_for_channel_count(std::uint32_t channel_count)
     }
 }
 
+OpenGlReadbackFormat rgba8_readback_format() noexcept
+{
+    return OpenGlReadbackFormat {
+        .pixel_format = gl_rgba,
+        .component_type = gl_unsigned_byte,
+        .bytes_per_pixel = 4U,
+    };
+}
+
+OpenGlReadbackFormat rgba32f_readback_format() noexcept
+{
+    return OpenGlReadbackFormat {
+        .pixel_format = gl_rgba,
+        .component_type = gl_float,
+        .bytes_per_pixel = 16U,
+    };
+}
+
+std::uint64_t readback_byte_count(
+    OpenGlReadbackFormat format,
+    std::uint32_t width,
+    std::uint32_t height) noexcept
+{
+    return static_cast<std::uint64_t>(width) * height * format.bytes_per_pixel;
+}
+
 const char* framebuffer_status_name(std::uint32_t status) noexcept
 {
     switch (status) {