Move OpenGL shape draw mappings

docs/modernization/build-inventory.md

@@ -130,7 +130,9 @@ Known local toolchain state:
   upload-type mapping used by legacy `Texture2D` and `RTT` creation. It also
   validates image channel-count to OpenGL texture format mapping, including
   invalid channel counts rejected by `Texture2D::create(Image)`, and
-  framebuffer status naming used by `RTT` diagnostics.
+  framebuffer status naming used by `RTT` diagnostics. It also validates
+  Shape index-type and fill/stroke primitive-mode mapping used by the legacy
+  mesh draw path.
 - `windows-msvc-vcpkg-headless` validates manifest install/configure/build/test
   for the current headless component matrix; see DEBT-0007 for remaining app
   and platform triplet migration.

docs/modernization/roadmap.md

@@ -390,9 +390,11 @@ OpenGL capability detection for framebuffer fetch, map-buffer alignment, and
 float texture support. It also owns the OpenGL texture upload-type mapping used
 by legacy `Texture2D` and `RTT` creation, plus image channel-count to texture
 format mapping for `Texture2D` image uploads and framebuffer status naming for
-`RTT` diagnostics. The legacy app delegates extension, upload-format, and
+`RTT` diagnostics. Mesh index-type and primitive-mode decisions used by legacy
-framebuffer diagnostic interpretation to that backend library, but the existing
+`Shape` drawing also live in `pp_renderer_gl`. The legacy app delegates
-renderer classes are not yet fully behind the renderer interfaces.
+extension, upload-format, framebuffer diagnostic, and mesh draw-mode
+interpretation to that backend library, but the existing renderer classes are
+not yet fully behind the renderer interfaces.
 
 Implementation tasks:
 
@@ -633,7 +635,8 @@ Results:
   alignment, desktop GL core float support, GLES float/half-float extensions,
   WebGL exclusion behavior, upload types for RGBA8/RGBA16F/RGBA32F internal
   formats, image channel-count format mapping including invalid counts, and
-  framebuffer status names.
+  framebuffer status names, plus Shape index-type and fill/stroke primitive
+  mode mapping.
 - PowerShell analyze automation returns JSON summaries and includes the shader
   validation target.
 - `windows-msvc-vcpkg-headless` configured through the Visual Studio bundled

src/renderer_gl/opengl_capabilities.cpp

@@ -5,8 +5,13 @@ namespace pp::renderer::gl {
 namespace {
 
 constexpr std::uint32_t gl_unsigned_byte = 0x1401U;
+constexpr std::uint32_t gl_unsigned_short = 0x1403U;
+constexpr std::uint32_t gl_unsigned_int = 0x1405U;
 constexpr std::uint32_t gl_float = 0x1406U;
 constexpr std::uint32_t gl_half_float = 0x140BU;
+constexpr std::uint32_t gl_points = 0x0000U;
+constexpr std::uint32_t gl_lines = 0x0001U;
+constexpr std::uint32_t gl_triangles = 0x0004U;
 constexpr std::uint32_t gl_red = 0x1903U;
 constexpr std::uint32_t gl_rgb = 0x1907U;
 constexpr std::uint32_t gl_rgba = 0x1908U;
@@ -124,4 +129,38 @@ const char* framebuffer_status_name(std::uint32_t status) noexcept
     }
 }
 
+std::uint32_t index_type_for_index_size(std::uint32_t index_size_bytes) noexcept
+{
+    switch (index_size_bytes) {
+    case 2:
+        return gl_unsigned_short;
+    case 4:
+        return gl_unsigned_int;
+    default:
+        return 0U;
+    }
+}
+
+std::uint32_t primitive_mode_for_fill_count(std::uint32_t vertex_or_index_count) noexcept
+{
+    if (vertex_or_index_count == 1U) {
+        return gl_points;
+    }
+
+    if (vertex_or_index_count == 2U) {
+        return gl_lines;
+    }
+
+    return gl_triangles;
+}
+
+std::uint32_t primitive_mode_for_stroke_count(std::uint32_t vertex_or_index_count) noexcept
+{
+    if (vertex_or_index_count == 1U) {
+        return gl_points;
+    }
+
+    return gl_lines;
+}
+
 }

src/renderer_gl/opengl_capabilities.h

@@ -33,5 +33,8 @@ struct OpenGlPixelFormat {
 [[nodiscard]] std::uint32_t texture_upload_type_for_internal_format(std::uint32_t internal_format) noexcept;
 [[nodiscard]] OpenGlPixelFormat texture_format_for_channel_count(std::uint32_t channel_count) noexcept;
 [[nodiscard]] const char* framebuffer_status_name(std::uint32_t status) noexcept;
+[[nodiscard]] std::uint32_t index_type_for_index_size(std::uint32_t index_size_bytes) noexcept;
+[[nodiscard]] std::uint32_t primitive_mode_for_fill_count(std::uint32_t vertex_or_index_count) noexcept;
+[[nodiscard]] std::uint32_t primitive_mode_for_stroke_count(std::uint32_t vertex_or_index_count) noexcept;
 
 }

src/shape.cpp

@@ -2,17 +2,20 @@
 #include "log.h"
 #include "shape.h"
 #include "app.h"
+#include "renderer_gl/opengl_capabilities.h"
+
+#include <cstdint>
 
 bool Shape::create_buffers(GLushort * idx, GLvoid * vertices, int isize, int vsize)
 {
-    index_type = GL_UNSIGNED_SHORT;
+    index_type = static_cast<GLenum>(pp::renderer::gl::index_type_for_index_size(sizeof(GLushort)));
     create_buffers_imp(idx, vertices, isize, vsize);
     return false;
 }
 
 bool Shape::create_buffers(GLuint* idx, GLvoid * vertices, int isize, int vsize)
 {
-    index_type = GL_UNSIGNED_INT;
+    index_type = static_cast<GLenum>(pp::renderer::gl::index_type_for_index_size(sizeof(GLuint)));
     create_buffers_imp(idx, vertices, isize, vsize);
     return false;
 }
@@ -119,11 +122,7 @@ void Shape::draw_fill() const
 {
     if (count[0] == 0) return;
 
-    GLenum type = GL_TRIANGLES;
+    const auto type = static_cast<GLenum>(pp::renderer::gl::primitive_mode_for_fill_count(count[0]));
-    if (count[0] == 1)
-        type = GL_POINTS;
-    if (count[0] == 2)
-        type = GL_LINES;
     App::I->render_task([=]
     {
 #if USE_VBO
@@ -157,9 +156,7 @@ void Shape::draw_stroke() const
 {
     if (count[0] == 0) return;
 
-    GLenum type = GL_LINES;
+    const auto type = static_cast<GLenum>(pp::renderer::gl::primitive_mode_for_stroke_count(count[1]));
-    if (count[1] == 1)
-        type = GL_POINTS;
     App::I->render_task([=]
     {
 #if USE_VBO

tests/renderer_gl/capabilities_tests.cpp

@@ -133,6 +133,29 @@ void names_framebuffer_status_codes(pp::tests::Harness& h)
     PP_EXPECT(h, pp::renderer::gl::framebuffer_status_name(0U) == std::string_view("UNKNOWN"));
 }
 
+void maps_shape_index_and_primitive_modes(pp::tests::Harness& h)
+{
+    constexpr std::uint32_t gl_points = 0x0000U;
+    constexpr std::uint32_t gl_lines = 0x0001U;
+    constexpr std::uint32_t gl_triangles = 0x0004U;
+    constexpr std::uint32_t gl_unsigned_short = 0x1403U;
+    constexpr std::uint32_t gl_unsigned_int = 0x1405U;
+
+    PP_EXPECT(h, pp::renderer::gl::index_type_for_index_size(2U) == gl_unsigned_short);
+    PP_EXPECT(h, pp::renderer::gl::index_type_for_index_size(4U) == gl_unsigned_int);
+    PP_EXPECT(h, pp::renderer::gl::index_type_for_index_size(1U) == 0U);
+    PP_EXPECT(h, pp::renderer::gl::index_type_for_index_size(8U) == 0U);
+
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_fill_count(1U) == gl_points);
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_fill_count(2U) == gl_lines);
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_fill_count(3U) == gl_triangles);
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_fill_count(99U) == gl_triangles);
+
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_stroke_count(1U) == gl_points);
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_stroke_count(2U) == gl_lines);
+    PP_EXPECT(h, pp::renderer::gl::primitive_mode_for_stroke_count(99U) == gl_lines);
+}
+
 }
 
 int main()
@@ -145,5 +168,6 @@ int main()
     harness.run("selects_texture_upload_type_from_internal_format", selects_texture_upload_type_from_internal_format);
     harness.run("maps_image_channel_count_to_texture_format", maps_image_channel_count_to_texture_format);
     harness.run("names_framebuffer_status_codes", names_framebuffer_status_codes);
+    harness.run("maps_shape_index_and_primitive_modes", maps_shape_index_and_primitive_modes);
     return harness.finish();
 }