Map render pass clear values to OpenGL

docs/modernization/build-inventory.md

@@ -201,7 +201,7 @@ Known local toolchain state:
   framebuffer targets, binding queries, attachment points, and completion
   status used by `RTT::create` and framebuffer bind/restore paths, plus RTT
   clear color/depth masks, renderer API render-pass color/depth/stencil
-  clear-mask mapping, and color-write-mask query tokens. `RTT` no longer
+  clear-mask and clear-value mapping, and color-write-mask query tokens. `RTT` no longer
   spells GL enum names directly. It also
   validates renderer API primitive-topology to OpenGL draw-mode mapping, Shape
   index-type, fill/stroke primitive-mode, buffer target, static upload usage,

docs/modernization/roadmap.md

@@ -455,7 +455,7 @@ render-target texture parameters, texture/renderbuffer targets, depth format,
 framebuffer targets, binding queries, attachment points, and completion status
 used by `RTT::create` and framebuffer bind/restore paths, also live in
 `pp_renderer_gl`. RTT clear color/depth masks, renderer API render-pass
-color/depth/stencil clear-mask mapping, and color-write-mask query tokens also
+color/depth/stencil clear-mask and clear-value mapping, and color-write-mask query tokens also
 live in `pp_renderer_gl`. `RTT` no longer spells GL enum names directly.
 Renderer API primitive-topology to OpenGL draw-mode mapping, mesh index-type
 and primitive-mode decisions used by legacy `Shape` drawing, plus Shape buffer

src/renderer_gl/opengl_capabilities.cpp

@@ -492,6 +492,20 @@ std::uint32_t clear_mask_for_render_pass(pp::renderer::RenderPassDesc desc) noex
     return mask;
 }
 
+OpenGlClearValues clear_values_for_render_pass(pp::renderer::RenderPassDesc desc) noexcept
+{
+    return OpenGlClearValues {
+        .color = {
+            desc.clear_color.r,
+            desc.clear_color.g,
+            desc.clear_color.b,
+            desc.clear_color.a,
+        },
+        .depth = desc.clear_depth,
+        .stencil = desc.clear_stencil,
+    };
+}
+
 std::uint32_t color_write_mask_query() noexcept
 {
     return gl_color_writemask;

src/renderer_gl/opengl_capabilities.h

@@ -72,6 +72,12 @@ struct OpenGlColorWriteMask {
     std::uint8_t a = 0;
 };
 
+struct OpenGlClearValues {
+    std::array<float, 4> color {};
+    float depth = 1.0F;
+    std::uint8_t stencil = 0;
+};
+
 struct OpenGlBlendState {
     std::uint8_t enabled = 0;
     std::uint32_t source_color_factor = 0;
@@ -153,6 +159,8 @@ struct OpenGlWindowsWglContextConfig {
 [[nodiscard]] std::uint32_t framebuffer_stencil_buffer_mask() noexcept;
 [[nodiscard]] std::uint32_t clear_mask_for_render_pass(
     pp::renderer::RenderPassDesc desc) noexcept;
+[[nodiscard]] OpenGlClearValues clear_values_for_render_pass(
+    pp::renderer::RenderPassDesc desc) noexcept;
 [[nodiscard]] std::uint32_t color_write_mask_query() noexcept;
 [[nodiscard]] std::uint32_t framebuffer_blit_filter(bool linear) noexcept;
 [[nodiscard]] OpenGlEnumMapping blit_filter_for_renderer_filter(

tests/renderer_gl/capabilities_tests.cpp

@@ -310,6 +310,49 @@ void maps_render_pass_clear_masks(pp::tests::Harness& h)
     PP_EXPECT(h, all_buffers == 0x00004500U);
 }
 
+void maps_render_pass_clear_values(pp::tests::Harness& h)
+{
+    const auto values = pp::renderer::gl::clear_values_for_render_pass(pp::renderer::RenderPassDesc {
+        .clear_color_enabled = true,
+        .clear_color = {
+            .r = 0.125F,
+            .g = 0.25F,
+            .b = 0.5F,
+            .a = 1.0F,
+        },
+        .clear_depth_enabled = true,
+        .clear_depth = 0.625F,
+        .clear_stencil_enabled = true,
+        .clear_stencil = 7U,
+    });
+    const auto disabled_values = pp::renderer::gl::clear_values_for_render_pass(pp::renderer::RenderPassDesc {
+        .clear_color_enabled = false,
+        .clear_color = {
+            .r = 1.0F,
+            .g = 0.75F,
+            .b = 0.5F,
+            .a = 0.25F,
+        },
+        .clear_depth_enabled = false,
+        .clear_depth = 0.125F,
+        .clear_stencil_enabled = false,
+        .clear_stencil = 13U,
+    });
+
+    PP_EXPECT(h, values.color[0] == 0.125F);
+    PP_EXPECT(h, values.color[1] == 0.25F);
+    PP_EXPECT(h, values.color[2] == 0.5F);
+    PP_EXPECT(h, values.color[3] == 1.0F);
+    PP_EXPECT(h, values.depth == 0.625F);
+    PP_EXPECT(h, values.stencil == 7U);
+    PP_EXPECT(h, disabled_values.color[0] == 1.0F);
+    PP_EXPECT(h, disabled_values.color[1] == 0.75F);
+    PP_EXPECT(h, disabled_values.color[2] == 0.5F);
+    PP_EXPECT(h, disabled_values.color[3] == 0.25F);
+    PP_EXPECT(h, disabled_values.depth == 0.125F);
+    PP_EXPECT(h, disabled_values.stencil == 13U);
+}
+
 void maps_renderer_primitive_topologies_to_draw_modes(pp::tests::Harness& h)
 {
     PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_renderer_topology(
@@ -963,6 +1006,7 @@ int main()
     harness.run("maps_framebuffer_render_target_parameters", maps_framebuffer_render_target_parameters);
     harness.run("maps_framebuffer_blit_parameters", maps_framebuffer_blit_parameters);
     harness.run("maps_render_pass_clear_masks", maps_render_pass_clear_masks);
+    harness.run("maps_render_pass_clear_values", maps_render_pass_clear_values);
     harness.run("maps_renderer_primitive_topologies_to_draw_modes", maps_renderer_primitive_topologies_to_draw_modes);
     harness.run("maps_shape_index_and_primitive_modes", maps_shape_index_and_primitive_modes);
     harness.run("maps_panopainter_cube_faces_to_texture_targets", maps_panopainter_cube_faces_to_texture_targets);