1 files changed, 274 insertions, 0 deletions
diff --git a/src/video_core/geometry_pipeline.cpp b/src/video_core/geometry_pipeline.cpp
new file mode 100644
index 0000000000..b146e2ecb1
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+++ b/src/video_core/geometry_pipeline.cpp
@@ -0,0 +1,274 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "video_core/geometry_pipeline.h"
+#include "video_core/pica_state.h"
+#include "video_core/regs.h"
+#include "video_core/renderer_base.h"
+#include "video_core/video_core.h"
+
+namespace Pica {
+
+/// An attribute buffering interface for different pipeline modes
+class GeometryPipelineBackend {
+public:
+    virtual ~GeometryPipelineBackend() = default;
+
+    /// Checks if there is no incomplete data transfer
+    virtual bool IsEmpty() const = 0;
+
+    /// Checks if the pipeline needs a direct input from index buffer
+    virtual bool NeedIndexInput() const = 0;
+
+    /// Submits an index from index buffer
+    virtual void SubmitIndex(unsigned int val) = 0;
+
+    /**
+     * Submits vertex attributes
+     * @param input attributes of a vertex output from vertex shader
+     * @return if the buffer is full and the geometry shader should be invoked
+     */
+    virtual bool SubmitVertex(const Shader::AttributeBuffer& input) = 0;
+};
+
+// In the Point mode, vertex attributes are sent to the input registers in the geometry shader unit.
+// The size of vertex shader outputs and geometry shader inputs are constants. Geometry shader is
+// invoked upon inputs buffer filled up by vertex shader outputs. For example, if we have a geometry
+// shader that takes 6 inputs, and the vertex shader outputs 2 attributes, it would take 3 vertices
+// for one geometry shader invocation.
+// TODO: what happens when the input size is not divisible by the output size?
+class GeometryPipeline_Point : public GeometryPipelineBackend {
+public:
+    GeometryPipeline_Point(const Regs& regs, Shader::GSUnitState& unit) : regs(regs), unit(unit) {
+        ASSERT(regs.pipeline.variable_primitive == 0);
+        ASSERT(regs.gs.input_to_uniform == 0);
+        vs_output_num = regs.pipeline.vs_outmap_total_minus_1_a + 1;
+        size_t gs_input_num = regs.gs.max_input_attribute_index + 1;
+        ASSERT(gs_input_num % vs_output_num == 0);
+        buffer_cur = attribute_buffer.attr;
+        buffer_end = attribute_buffer.attr + gs_input_num;
+    }
+
+    bool IsEmpty() const override {
+        return buffer_cur == attribute_buffer.attr;
+    }
+
+    bool NeedIndexInput() const override {
+        return false;
+    }
+
+    void SubmitIndex(unsigned int val) override {
+        UNREACHABLE();
+    }
+
+    bool SubmitVertex(const Shader::AttributeBuffer& input) override {
+        buffer_cur = std::copy(input.attr, input.attr + vs_output_num, buffer_cur);
+        if (buffer_cur == buffer_end) {
+            buffer_cur = attribute_buffer.attr;
+            unit.LoadInput(regs.gs, attribute_buffer);
+            return true;
+        }
+        return false;
+    }
+
+private:
+    const Regs& regs;
+    Shader::GSUnitState& unit;
+    Shader::AttributeBuffer attribute_buffer;
+    Math::Vec4<float24>* buffer_cur;
+    Math::Vec4<float24>* buffer_end;
+    unsigned int vs_output_num;
+};
+
+// In VariablePrimitive mode, vertex attributes are buffered into the uniform registers in the
+// geometry shader unit. The number of vertex is variable, which is specified by the first index
+// value in the batch. This mode is usually used for subdivision.
+class GeometryPipeline_VariablePrimitive : public GeometryPipelineBackend {
+public:
+    GeometryPipeline_VariablePrimitive(const Regs& regs, Shader::ShaderSetup& setup)
+        : regs(regs), setup(setup) {
+        ASSERT(regs.pipeline.variable_primitive == 1);
+        ASSERT(regs.gs.input_to_uniform == 1);
+        vs_output_num = regs.pipeline.vs_outmap_total_minus_1_a + 1;
+    }
+
+    bool IsEmpty() const override {
+        return need_index;
+    }
+
+    bool NeedIndexInput() const override {
+        return need_index;
+    }
+
+    void SubmitIndex(unsigned int val) override {
+        DEBUG_ASSERT(need_index);
+
+        // The number of vertex input is put to the uniform register
+        float24 vertex_num = float24::FromFloat32(val);
+        setup.uniforms.f[0] = Math::MakeVec(vertex_num, vertex_num, vertex_num, vertex_num);
+
+        // The second uniform register and so on are used for receiving input vertices
+        buffer_cur = setup.uniforms.f + 1;
+
+        main_vertex_num = regs.pipeline.variable_vertex_main_num_minus_1 + 1;
+        total_vertex_num = val;
+        need_index = false;
+    }
+
+    bool SubmitVertex(const Shader::AttributeBuffer& input) override {
+        DEBUG_ASSERT(!need_index);
+        if (main_vertex_num != 0) {
+            // For main vertices, receive all attributes
+            buffer_cur = std::copy(input.attr, input.attr + vs_output_num, buffer_cur);
+            --main_vertex_num;
+        } else {
+            // For other vertices, only receive the first attribute (usually the position)
+            *(buffer_cur++) = input.attr[0];
+        }
+        --total_vertex_num;
+
+        if (total_vertex_num == 0) {
+            need_index = true;
+            return true;
+        }
+
+        return false;
+    }
+
+private:
+    bool need_index = true;
+    const Regs& regs;
+    Shader::ShaderSetup& setup;
+    unsigned int main_vertex_num;
+    unsigned int total_vertex_num;
+    Math::Vec4<float24>* buffer_cur;
+    unsigned int vs_output_num;
+};
+
+// In FixedPrimitive mode, vertex attributes are buffered into the uniform registers in the geometry
+// shader unit. The number of vertex per shader invocation is constant. This is usually used for
+// particle system.
+class GeometryPipeline_FixedPrimitive : public GeometryPipelineBackend {
+public:
+    GeometryPipeline_FixedPrimitive(const Regs& regs, Shader::ShaderSetup& setup)
+        : regs(regs), setup(setup) {
+        ASSERT(regs.pipeline.variable_primitive == 0);
+        ASSERT(regs.gs.input_to_uniform == 1);
+        vs_output_num = regs.pipeline.vs_outmap_total_minus_1_a + 1;
+        ASSERT(vs_output_num == regs.pipeline.gs_config.stride_minus_1 + 1);
+        size_t vertex_num = regs.pipeline.gs_config.fixed_vertex_num_minus_1 + 1;
+        buffer_cur = buffer_begin = setup.uniforms.f + regs.pipeline.gs_config.start_index;
+        buffer_end = buffer_begin + vs_output_num * vertex_num;
+    }
+
+    bool IsEmpty() const override {
+        return buffer_cur == buffer_begin;
+    }
+
+    bool NeedIndexInput() const override {
+        return false;
+    }
+
+    void SubmitIndex(unsigned int val) override {
+        UNREACHABLE();
+    }
+
+    bool SubmitVertex(const Shader::AttributeBuffer& input) override {
+        buffer_cur = std::copy(input.attr, input.attr + vs_output_num, buffer_cur);
+        if (buffer_cur == buffer_end) {
+            buffer_cur = buffer_begin;
+            return true;
+        }
+        return false;
+    }
+
+private:
+    const Regs& regs;
+    Shader::ShaderSetup& setup;
+    Math::Vec4<float24>* buffer_begin;
+    Math::Vec4<float24>* buffer_cur;
+    Math::Vec4<float24>* buffer_end;
+    unsigned int vs_output_num;
+};
+
+GeometryPipeline::GeometryPipeline(State& state) : state(state) {}
+
+GeometryPipeline::~GeometryPipeline() = default;
+
+void GeometryPipeline::SetVertexHandler(Shader::VertexHandler vertex_handler) {
+    this->vertex_handler = vertex_handler;
+}
+
+void GeometryPipeline::Setup(Shader::ShaderEngine* shader_engine) {
+    if (!backend)
+        return;
+
+    this->shader_engine = shader_engine;
+    shader_engine->SetupBatch(state.gs, state.regs.gs.main_offset);
+}
+
+void GeometryPipeline::Reconfigure() {
+    ASSERT(!backend || backend->IsEmpty());
+
+    if (state.regs.pipeline.use_gs == PipelineRegs::UseGS::No) {
+        backend = nullptr;
+        return;
+    }
+
+    ASSERT(state.regs.pipeline.use_gs == PipelineRegs::UseGS::Yes);
+
+    // The following assumes that when geometry shader is in use, the shader unit 3 is configured as
+    // a geometry shader unit.
+    // TODO: what happens if this is not true?
+    ASSERT(state.regs.pipeline.gs_unit_exclusive_configuration == 1);
+    ASSERT(state.regs.gs.shader_mode == ShaderRegs::ShaderMode::GS);
+
+    state.gs_unit.ConfigOutput(state.regs.gs);
+
+    ASSERT(state.regs.pipeline.vs_outmap_total_minus_1_a ==
+           state.regs.pipeline.vs_outmap_total_minus_1_b);
+
+    switch (state.regs.pipeline.gs_config.mode) {
+    case PipelineRegs::GSMode::Point:
+        backend = std::make_unique<GeometryPipeline_Point>(state.regs, state.gs_unit);
+        break;
+    case PipelineRegs::GSMode::VariablePrimitive:
+        backend = std::make_unique<GeometryPipeline_VariablePrimitive>(state.regs, state.gs);
+        break;
+    case PipelineRegs::GSMode::FixedPrimitive:
+        backend = std::make_unique<GeometryPipeline_FixedPrimitive>(state.regs, state.gs);
+        break;
+    default:
+        UNREACHABLE();
+    }
+}
+
+bool GeometryPipeline::NeedIndexInput() const {
+    if (!backend)
+        return false;
+    return backend->NeedIndexInput();
+}
+
+void GeometryPipeline::SubmitIndex(unsigned int val) {
+    backend->SubmitIndex(val);
+}
+
+void GeometryPipeline::SubmitVertex(const Shader::AttributeBuffer& input) {
+    if (!backend) {
+        // No backend means the geometry shader is disabled, so we send the vertex shader output
+        // directly to the primitive assembler.
+        vertex_handler(input);
+    } else {
+        if (backend->SubmitVertex(input)) {
+            shader_engine->Run(state.gs, state.gs_unit);
+
+            // The uniform b15 is set to true after every geometry shader invocation. This is useful
+            // for the shader to know if this is the first invocation in a batch, if the program set
+            // b15 to false first.
+            state.gs.uniforms.b[15] = true;
+        }
+    }
+}
+
+} // namespace Pica