citra/src/video_core/renderer_opengl/gl_state.h

// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <array>
#include <glad/glad.h>

namespace OpenGL {

namespace TextureUnits {

struct TextureUnit {
    GLint id;
    constexpr GLenum Enum() const {
        return static_cast<GLenum>(GL_TEXTURE0 + id);
    }
};

constexpr TextureUnit PicaTexture(int unit) {
    return TextureUnit{unit};
}

constexpr TextureUnit TextureCube{6};
constexpr TextureUnit TextureBufferLUT_LF{3};
constexpr TextureUnit TextureBufferLUT_RG{4};
constexpr TextureUnit TextureBufferLUT_RGBA{5};
constexpr TextureUnit TextureNormalMap{7};
constexpr TextureUnit TextureColorBuffer{10};

} // namespace TextureUnits

namespace ImageUnits {
constexpr GLuint ShadowTexturePX = 0;
constexpr GLuint ShadowTextureNX = 1;
constexpr GLuint ShadowTexturePY = 2;
constexpr GLuint ShadowTextureNY = 3;
constexpr GLuint ShadowTexturePZ = 4;
constexpr GLuint ShadowTextureNZ = 5;
constexpr GLuint ShadowBuffer = 6;
} // namespace ImageUnits

class OpenGLState {
public:
    struct {
        bool enabled;      // GL_CULL_FACE
        GLenum mode;       // GL_CULL_FACE_MODE
        GLenum front_face; // GL_FRONT_FACE
    } cull;

    struct {
        bool test_enabled;    // GL_DEPTH_TEST
        GLenum test_func;     // GL_DEPTH_FUNC
        GLboolean write_mask; // GL_DEPTH_WRITEMASK
    } depth;

    struct {
        GLboolean red_enabled;
        GLboolean green_enabled;
        GLboolean blue_enabled;
        GLboolean alpha_enabled;
    } color_mask; // GL_COLOR_WRITEMASK

    struct {
        bool test_enabled;          // GL_STENCIL_TEST
        GLenum test_func;           // GL_STENCIL_FUNC
        GLint test_ref;             // GL_STENCIL_REF
        GLuint test_mask;           // GL_STENCIL_VALUE_MASK
        GLuint write_mask;          // GL_STENCIL_WRITEMASK
        GLenum action_stencil_fail; // GL_STENCIL_FAIL
        GLenum action_depth_fail;   // GL_STENCIL_PASS_DEPTH_FAIL
        GLenum action_depth_pass;   // GL_STENCIL_PASS_DEPTH_PASS
    } stencil;

    struct {
        bool enabled;        // GL_BLEND
        GLenum rgb_equation; // GL_BLEND_EQUATION_RGB
        GLenum a_equation;   // GL_BLEND_EQUATION_ALPHA
        GLenum src_rgb_func; // GL_BLEND_SRC_RGB
        GLenum dst_rgb_func; // GL_BLEND_DST_RGB
        GLenum src_a_func;   // GL_BLEND_SRC_ALPHA
        GLenum dst_a_func;   // GL_BLEND_DST_ALPHA

        struct {
            GLclampf red;
            GLclampf green;
            GLclampf blue;
            GLclampf alpha;
        } color; // GL_BLEND_COLOR
    } blend;

    GLenum logic_op; // GL_LOGIC_OP_MODE

    // 3 texture units - one for each that is used in PICA fragment shader emulation
    struct TextureUnit {
        GLuint texture_2d; // GL_TEXTURE_BINDING_2D
        GLuint sampler;    // GL_SAMPLER_BINDING
    };
    std::array<TextureUnit, 3> texture_units;

    struct {
        GLuint texture_cube; // GL_TEXTURE_BINDING_CUBE_MAP
        GLuint sampler;      // GL_SAMPLER_BINDING
    } texture_cube_unit;

    struct {
        GLuint texture_buffer; // GL_TEXTURE_BINDING_BUFFER
    } texture_buffer_lut_lf;

    struct {
        GLuint texture_buffer; // GL_TEXTURE_BINDING_BUFFER
    } texture_buffer_lut_rg;

    struct {
        GLuint texture_buffer; // GL_TEXTURE_BINDING_BUFFER
    } texture_buffer_lut_rgba;

    struct {
        GLuint texture_2d; // GL_TEXTURE_BINDING_2D
    } color_buffer;

    // GL_IMAGE_BINDING_NAME
    GLuint image_shadow_buffer;
    union {
        std::array<GLuint, 6> image_shadow_texture;
        struct {
            GLuint image_shadow_texture_px;
            GLuint image_shadow_texture_nx;
            GLuint image_shadow_texture_py;
            GLuint image_shadow_texture_ny;
            GLuint image_shadow_texture_pz;
            GLuint image_shadow_texture_nz;
        };
    };

    struct {
        GLuint read_framebuffer; // GL_READ_FRAMEBUFFER_BINDING
        GLuint draw_framebuffer; // GL_DRAW_FRAMEBUFFER_BINDING
        GLuint vertex_array;     // GL_VERTEX_ARRAY_BINDING
        GLuint vertex_buffer;    // GL_ARRAY_BUFFER_BINDING
        GLuint uniform_buffer;   // GL_UNIFORM_BUFFER_BINDING
        GLuint shader_program;   // GL_CURRENT_PROGRAM
        GLuint program_pipeline; // GL_PROGRAM_PIPELINE_BINDING
    } draw;

    struct {
        bool enabled; // GL_SCISSOR_TEST
        GLint x;
        GLint y;
        GLsizei width;
        GLsizei height;
    } scissor;

    struct {
        GLint x;
        GLint y;
        GLsizei width;
        GLsizei height;
    } viewport;

    std::array<bool, 2> clip_distance; // GL_CLIP_DISTANCE

    GLuint renderbuffer; // GL_RENDERBUFFER_BINDING

    OpenGLState();

    /// Get the currently active OpenGL state
    static OpenGLState GetCurState() {
        return cur_state;
    }

    bool EmulateColorBlend() const {
        return blend.rgb_equation == GL_MIN || blend.rgb_equation == GL_MAX;
    }

    bool EmulateAlphaBlend() const {
        return blend.a_equation == GL_MIN || blend.a_equation == GL_MAX;
    }

    /// Apply this state as the current OpenGL state
    void Apply() const;

    /// Resets any references to the given resource
    OpenGLState& ResetTexture(GLuint handle);
    OpenGLState& ResetSampler(GLuint handle);
    OpenGLState& ResetProgram(GLuint handle);
    OpenGLState& ResetPipeline(GLuint handle);
    OpenGLState& ResetBuffer(GLuint handle);
    OpenGLState& ResetVertexArray(GLuint handle);
    OpenGLState& ResetFramebuffer(GLuint handle);
    OpenGLState& ResetRenderbuffer(GLuint handle);

private:
    static OpenGLState cur_state;
};

} // namespace OpenGL