Expand renderer API interfaces

docs/modernization/roadmap.md

@@ -355,8 +355,9 @@ Goal: make OpenGL an implementation detail and establish parity tests before
 adding new backends.
 
 Status: started. `pp_renderer_api` exists as a headless renderer-neutral target
-with texture descriptor, byte-size, and readback bounds validation. OpenGL
+with texture descriptor, byte-size, viewport, mesh, readback bounds, command
-classes are not yet behind these interfaces.
+context, render device, shader, mesh, render target, readback, and trace
+interface validation. OpenGL classes are not yet behind these interfaces.
 
 Implementation tasks:
 

src/renderer_api/renderer_api.cpp

@@ -1,5 +1,6 @@
 #include "renderer_api/renderer_api.h"
 
+#include <cmath>
 #include <limits>
 
 namespace pp::renderer {
@@ -66,6 +67,62 @@ pp::foundation::Result<std::uint64_t> texture_byte_size(TextureDesc desc) noexce
     return pp::foundation::Result<std::uint64_t>::success(bytes);
 }
 
+pp::foundation::Status validate_viewport(Viewport viewport, Extent2D target_extent) noexcept
+{
+    const auto extent_status = validate_extent(target_extent);
+    if (!extent_status.ok()) {
+        return extent_status;
+    }
+
+    if (viewport.x < 0 || viewport.y < 0) {
+        return pp::foundation::Status::invalid_argument("viewport origin must be non-negative");
+    }
+
+    if (viewport.width == 0 || viewport.height == 0) {
+        return pp::foundation::Status::invalid_argument("viewport size must be greater than zero");
+    }
+
+    if (!std::isfinite(viewport.min_depth) || !std::isfinite(viewport.max_depth)) {
+        return pp::foundation::Status::invalid_argument("viewport depth range must be finite");
+    }
+
+    if (viewport.min_depth < 0.0F || viewport.max_depth > 1.0F || viewport.min_depth > viewport.max_depth) {
+        return pp::foundation::Status::out_of_range("viewport depth range must be within 0..1 and ordered");
+    }
+
+    const auto x = static_cast<std::uint32_t>(viewport.x);
+    const auto y = static_cast<std::uint32_t>(viewport.y);
+    if (x > target_extent.width || y > target_extent.height) {
+        return pp::foundation::Status::out_of_range("viewport origin is outside the render target");
+    }
+
+    if (viewport.width > target_extent.width - x || viewport.height > target_extent.height - y) {
+        return pp::foundation::Status::out_of_range("viewport exceeds render target bounds");
+    }
+
+    return pp::foundation::Status::success();
+}
+
+pp::foundation::Status validate_mesh_desc(MeshDesc desc) noexcept
+{
+    if (desc.vertex_count == 0) {
+        return pp::foundation::Status::invalid_argument("mesh must contain at least one vertex");
+    }
+
+    if (desc.vertex_count > max_mesh_vertices || desc.index_count > max_mesh_vertices) {
+        return pp::foundation::Status::out_of_range("mesh vertex or index count exceeds the configured limit");
+    }
+
+    switch (desc.topology) {
+    case PrimitiveTopology::triangles:
+    case PrimitiveTopology::triangle_strip:
+    case PrimitiveTopology::lines:
+        return pp::foundation::Status::success();
+    }
+
+    return pp::foundation::Status::invalid_argument("mesh topology is not supported");
+}
+
 pp::foundation::Status validate_readback_region(TextureDesc desc, ReadbackRegion region) noexcept
 {
     const auto extent_status = validate_extent(desc.extent);
@@ -102,4 +159,18 @@ const char* texture_format_name(TextureFormat format) noexcept
     return "unknown";
 }
 
+const char* primitive_topology_name(PrimitiveTopology topology) noexcept
+{
+    switch (topology) {
+    case PrimitiveTopology::triangles:
+        return "triangles";
+    case PrimitiveTopology::triangle_strip:
+        return "triangle_strip";
+    case PrimitiveTopology::lines:
+        return "lines";
+    }
+
+    return "unknown";
+}
+
 }

src/renderer_api/renderer_api.h

@@ -2,11 +2,13 @@
 
 #include "foundation/result.h"
 
+#include <cstddef>
 #include <cstdint>
 
 namespace pp::renderer {
 
 constexpr std::uint32_t max_texture_dimension = 32768;
+constexpr std::uint32_t max_mesh_vertices = 16777216;
 constexpr std::uint64_t max_texture_bytes = 1024ULL * 1024ULL * 1024ULL;
 
 enum class TextureFormat : std::uint8_t {
@@ -33,12 +35,70 @@ struct ReadbackRegion {
     std::uint32_t height = 0;
 };
 
+struct Viewport {
+    std::int32_t x = 0;
+    std::int32_t y = 0;
+    std::uint32_t width = 0;
+    std::uint32_t height = 0;
+    float min_depth = 0.0F;
+    float max_depth = 1.0F;
+};
+
+struct ClearColor {
+    float r = 0.0F;
+    float g = 0.0F;
+    float b = 0.0F;
+    float a = 0.0F;
+};
+
+enum class PrimitiveTopology : std::uint8_t {
+    triangles,
+    triangle_strip,
+    lines,
+};
+
+struct MeshDesc {
+    std::uint32_t vertex_count = 0;
+    std::uint32_t index_count = 0;
+    PrimitiveTopology topology = PrimitiveTopology::triangles;
+};
+
+struct ShaderStageSource {
+    const char* entry_point = "main";
+    const char* source = nullptr;
+    std::size_t source_size = 0;
+};
+
+struct ShaderProgramDesc {
+    const char* debug_name = "";
+    ShaderStageSource vertex;
+    ShaderStageSource fragment;
+};
+
 class ITexture2D {
 public:
     virtual ~ITexture2D() = default;
     [[nodiscard]] virtual TextureDesc desc() const noexcept = 0;
 };
 
+class IRenderTarget {
+public:
+    virtual ~IRenderTarget() = default;
+    [[nodiscard]] virtual TextureDesc color_desc() const noexcept = 0;
+};
+
+class IShaderProgram {
+public:
+    virtual ~IShaderProgram() = default;
+    [[nodiscard]] virtual const char* debug_name() const noexcept = 0;
+};
+
+class IMesh {
+public:
+    virtual ~IMesh() = default;
+    [[nodiscard]] virtual MeshDesc desc() const noexcept = 0;
+};
+
 class IReadbackBuffer {
 public:
     virtual ~IReadbackBuffer() = default;
@@ -51,10 +111,34 @@ public:
     virtual void marker(const char* component, const char* name) noexcept = 0;
 };
 
+class ICommandContext {
+public:
+    virtual ~ICommandContext() = default;
+    [[nodiscard]] virtual pp::foundation::Status begin_render_pass(
+        IRenderTarget& target,
+        ClearColor clear_color) noexcept = 0;
+    [[nodiscard]] virtual pp::foundation::Status set_viewport(Viewport viewport) noexcept = 0;
+    [[nodiscard]] virtual pp::foundation::Status bind_shader(IShaderProgram& shader) noexcept = 0;
+    [[nodiscard]] virtual pp::foundation::Status bind_mesh(IMesh& mesh) noexcept = 0;
+    [[nodiscard]] virtual pp::foundation::Status draw() noexcept = 0;
+    virtual void end_render_pass() noexcept = 0;
+};
+
+class IRenderDevice {
+public:
+    virtual ~IRenderDevice() = default;
+    [[nodiscard]] virtual const char* backend_name() const noexcept = 0;
+    [[nodiscard]] virtual ICommandContext& immediate_context() noexcept = 0;
+    [[nodiscard]] virtual IRenderTrace* trace() noexcept = 0;
+};
+
 [[nodiscard]] std::uint32_t bytes_per_pixel(TextureFormat format) noexcept;
 [[nodiscard]] pp::foundation::Status validate_extent(Extent2D extent) noexcept;
+[[nodiscard]] pp::foundation::Status validate_viewport(Viewport viewport, Extent2D target_extent) noexcept;
+[[nodiscard]] pp::foundation::Status validate_mesh_desc(MeshDesc desc) noexcept;
 [[nodiscard]] pp::foundation::Result<std::uint64_t> texture_byte_size(TextureDesc desc) noexcept;
 [[nodiscard]] pp::foundation::Status validate_readback_region(TextureDesc desc, ReadbackRegion region) noexcept;
 [[nodiscard]] const char* texture_format_name(TextureFormat format) noexcept;
+[[nodiscard]] const char* primitive_topology_name(PrimitiveTopology topology) noexcept;
 
 }

tests/renderer_api/renderer_api_tests.cpp

@@ -4,18 +4,136 @@
 #include <string_view>
 
 using pp::foundation::StatusCode;
+using pp::renderer::ClearColor;
 using pp::renderer::Extent2D;
+using pp::renderer::ICommandContext;
+using pp::renderer::IMesh;
+using pp::renderer::IRenderDevice;
+using pp::renderer::IRenderTarget;
+using pp::renderer::IRenderTrace;
+using pp::renderer::IShaderProgram;
+using pp::renderer::MeshDesc;
+using pp::renderer::PrimitiveTopology;
 using pp::renderer::ReadbackRegion;
 using pp::renderer::TextureDesc;
 using pp::renderer::TextureFormat;
+using pp::renderer::Viewport;
 using pp::renderer::max_texture_dimension;
+using pp::renderer::primitive_topology_name;
 using pp::renderer::texture_byte_size;
 using pp::renderer::texture_format_name;
 using pp::renderer::validate_extent;
+using pp::renderer::validate_mesh_desc;
 using pp::renderer::validate_readback_region;
+using pp::renderer::validate_viewport;
 
 namespace {
 
+class FakeRenderTarget final : public IRenderTarget {
+public:
+    [[nodiscard]] TextureDesc color_desc() const noexcept override
+    {
+        return TextureDesc {
+            .extent = Extent2D { .width = 64, .height = 32 },
+            .format = TextureFormat::rgba8,
+            .render_target = true,
+        };
+    }
+};
+
+class FakeShaderProgram final : public IShaderProgram {
+public:
+    [[nodiscard]] const char* debug_name() const noexcept override
+    {
+        return "fake-shader";
+    }
+};
+
+class FakeMesh final : public IMesh {
+public:
+    [[nodiscard]] MeshDesc desc() const noexcept override
+    {
+        return MeshDesc { .vertex_count = 3, .index_count = 0, .topology = PrimitiveTopology::triangles };
+    }
+};
+
+class FakeTrace final : public IRenderTrace {
+public:
+    void marker(const char* component, const char* name) noexcept override
+    {
+        last_component = component;
+        last_name = name;
+    }
+
+    const char* last_component = nullptr;
+    const char* last_name = nullptr;
+};
+
+class FakeCommandContext final : public ICommandContext {
+public:
+    [[nodiscard]] pp::foundation::Status begin_render_pass(
+        IRenderTarget& target,
+        ClearColor) noexcept override
+    {
+        in_render_pass = true;
+        return validate_extent(target.color_desc().extent);
+    }
+
+    [[nodiscard]] pp::foundation::Status set_viewport(Viewport viewport) noexcept override
+    {
+        if (!in_render_pass) {
+            return pp::foundation::Status::invalid_argument("render pass has not begun");
+        }
+        return validate_viewport(viewport, Extent2D { .width = 64, .height = 32 });
+    }
+
+    [[nodiscard]] pp::foundation::Status bind_shader(IShaderProgram& shader) noexcept override
+    {
+        shader_name = shader.debug_name();
+        return pp::foundation::Status::success();
+    }
+
+    [[nodiscard]] pp::foundation::Status bind_mesh(IMesh& mesh) noexcept override
+    {
+        return validate_mesh_desc(mesh.desc());
+    }
+
+    [[nodiscard]] pp::foundation::Status draw() noexcept override
+    {
+        return in_render_pass ? pp::foundation::Status::success()
+                              : pp::foundation::Status::invalid_argument("render pass has not begun");
+    }
+
+    void end_render_pass() noexcept override
+    {
+        in_render_pass = false;
+    }
+
+    bool in_render_pass = false;
+    const char* shader_name = nullptr;
+};
+
+class FakeRenderDevice final : public IRenderDevice {
+public:
+    [[nodiscard]] const char* backend_name() const noexcept override
+    {
+        return "fake";
+    }
+
+    [[nodiscard]] ICommandContext& immediate_context() noexcept override
+    {
+        return context;
+    }
+
+    [[nodiscard]] IRenderTrace* trace() noexcept override
+    {
+        return &trace_recorder;
+    }
+
+    FakeCommandContext context;
+    FakeTrace trace_recorder;
+};
+
 void computes_texture_sizes(pp::tests::Harness& h)
 {
     const auto rgba = texture_byte_size(TextureDesc {
@@ -74,6 +192,60 @@ void validates_readback_bounds(pp::tests::Harness& h)
     PP_EXPECT(h, overrun.code == StatusCode::out_of_range);
 }
 
+void validates_viewports_and_mesh_descriptors(pp::tests::Harness& h)
+{
+    const Extent2D target { .width = 64, .height = 32 };
+
+    PP_EXPECT(h, validate_viewport(
+                     Viewport { .x = 0, .y = 0, .width = 64, .height = 32, .min_depth = 0.0F, .max_depth = 1.0F },
+                     target)
+                     .ok());
+    PP_EXPECT(h, validate_mesh_desc(MeshDesc { .vertex_count = 3, .topology = PrimitiveTopology::triangles }).ok());
+    PP_EXPECT(h, primitive_topology_name(PrimitiveTopology::lines) == std::string_view("lines"));
+
+    const auto negative_origin = validate_viewport(Viewport { .x = -1, .y = 0, .width = 1, .height = 1 }, target);
+    const auto too_wide = validate_viewport(Viewport { .x = 63, .y = 0, .width = 2, .height = 1 }, target);
+    const auto bad_depth = validate_viewport(
+        Viewport { .x = 0, .y = 0, .width = 1, .height = 1, .min_depth = 0.75F, .max_depth = 0.25F },
+        target);
+    const auto empty_mesh = validate_mesh_desc(MeshDesc {});
+
+    PP_EXPECT(h, !negative_origin.ok());
+    PP_EXPECT(h, negative_origin.code == StatusCode::invalid_argument);
+    PP_EXPECT(h, !too_wide.ok());
+    PP_EXPECT(h, too_wide.code == StatusCode::out_of_range);
+    PP_EXPECT(h, !bad_depth.ok());
+    PP_EXPECT(h, bad_depth.code == StatusCode::out_of_range);
+    PP_EXPECT(h, !empty_mesh.ok());
+    PP_EXPECT(h, empty_mesh.code == StatusCode::invalid_argument);
+}
+
+void renderer_interfaces_support_backend_neutral_dispatch(pp::tests::Harness& h)
+{
+    FakeRenderDevice device;
+    FakeRenderTarget target;
+    FakeShaderProgram shader;
+    FakeMesh mesh;
+
+    PP_EXPECT(h, device.backend_name() == std::string_view("fake"));
+    device.trace()->marker("renderer", "begin");
+    PP_EXPECT(h, device.trace_recorder.last_component == std::string_view("renderer"));
+    PP_EXPECT(h, device.trace_recorder.last_name == std::string_view("begin"));
+
+    auto& context = device.immediate_context();
+    PP_EXPECT(h, context.begin_render_pass(target, ClearColor { .r = 0.1F, .g = 0.2F, .b = 0.3F, .a = 1.0F }).ok());
+    PP_EXPECT(h, context.set_viewport(Viewport { .x = 0, .y = 0, .width = 64, .height = 32 }).ok());
+    PP_EXPECT(h, context.bind_shader(shader).ok());
+    PP_EXPECT(h, context.bind_mesh(mesh).ok());
+    PP_EXPECT(h, context.draw().ok());
+    context.end_render_pass();
+
+    const auto draw_after_end = context.draw();
+    PP_EXPECT(h, !draw_after_end.ok());
+    PP_EXPECT(h, draw_after_end.code == StatusCode::invalid_argument);
+    PP_EXPECT(h, device.context.shader_name == std::string_view("fake-shader"));
+}
+
 }
 
 int main()
@@ -82,5 +254,7 @@ int main()
     harness.run("computes_texture_sizes", computes_texture_sizes);
     harness.run("rejects_invalid_or_excessive_extents", rejects_invalid_or_excessive_extents);
     harness.run("validates_readback_bounds", validates_readback_bounds);
+    harness.run("validates_viewports_and_mesh_descriptors", validates_viewports_and_mesh_descriptors);
+    harness.run("renderer_interfaces_support_backend_neutral_dispatch", renderer_interfaces_support_backend_neutral_dispatch);
     return harness.finish();
 }