Panda3DS/include/renderer_gl/surfaces.hpp

#pragma once
#include "boost/icl/interval.hpp"
#include "helpers.hpp"
#include "opengl.hpp"

template <typename T>
using Interval = boost::icl::right_open_interval<T>;

struct ColourBuffer {
    enum class Formats : u32 {
        RGBA8 = 0,
        BGR8 = 1,
        RGB5A1 = 2,
        RGB565 = 3,
        RGBA4 = 4,
        
        Trash1 = 5, Trash2 = 6, Trash3 = 7 // Technically selectable, but their function is unknown
    };

    u32 location;
    Formats format;
    OpenGL::uvec2 size;
    bool valid;

    // Range of VRAM taken up by buffer
    Interval<u32> range;
    // OpenGL resources allocated to buffer
    OpenGL::Texture texture;
    OpenGL::Framebuffer fbo;

    ColourBuffer() : valid(false) {}

    ColourBuffer(u32 loc, Formats format, u32 x, u32 y, bool valid = true)
        : location(loc), format(format), size({x, y}), valid(valid) {

        u64 endLoc = (u64)loc + sizeInBytes();
        // Check if start and end are valid here
        range = Interval<u32>(loc, (u32)endLoc);
    }

    void allocate() {
        // Create texture for the FBO, setting up filters and the like
        // Reading back the current texture is slow, but allocate calls should be few and far between.
        // If this becomes a bottleneck, we can fix it semi-easily
        auto prevTexture = OpenGL::getTex2D();
        texture.create(size.x(), size.y(), GL_RGBA8);
        texture.bind();
        texture.setMinFilter(OpenGL::Linear);
        texture.setMagFilter(OpenGL::Linear);
        glBindTexture(GL_TEXTURE_2D, prevTexture);

        //Helpers::panic("Creating FBO: %d, %d\n", size.x(), size.y());

        fbo.createWithDrawTexture(texture);
        fbo.bind(OpenGL::DrawAndReadFramebuffer);

        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
            Helpers::panic("Incomplete framebuffer");

        // TODO: This should not clear the framebuffer contents. It should load them from VRAM.
        GLint oldViewport[4];
        glGetIntegerv(GL_VIEWPORT, oldViewport);
        OpenGL::setViewport(size.x(), size.y());
        OpenGL::setClearColor(0.0, 0.0, 0.0, 1.0);
        OpenGL::clearColor();
        OpenGL::setViewport(oldViewport[0], oldViewport[1], oldViewport[2], oldViewport[3]);
    }

    void free() {
        valid = false;

        if (texture.exists() || fbo.exists())
            Helpers::panic("Make this buffer free itself");
    }

    bool matches(ColourBuffer& other) {
        return location == other.location && format == other.format &&
            size.x() == other.size.x() && size.y() == other.size.y();
    }

    // Size occupied by each pixel in bytes
    // All formats are 16BPP except for RGBA8 (32BPP) and BGR8 (24BPP)
    size_t sizePerPixel() {
        switch (format) {
            case Formats::BGR8: return 3;
            case Formats::RGBA8: return 4;
            default: return 2;
        }
    }

    size_t sizeInBytes() {
        return (size_t)size.x() * (size_t)size.y() * sizePerPixel();
    }
};

struct DepthBuffer {
    enum class Formats : u32 {
        Depth16 = 0,
        Garbage = 1,
        Depth24 = 2,
        Depth24Stencil8 = 3
    };

    u32 location;
    Formats format;
    OpenGL::uvec2 size; // Implicitly set to the size of the framebuffer
    bool valid;

    // Range of VRAM taken up by buffer
    Interval<u32> range;
    // OpenGL texture used for storing depth/stencil
    OpenGL::Texture texture;

    DepthBuffer() : valid(false) {}

    DepthBuffer(u32 loc, Formats format, u32 x, u32 y, bool valid = true) :
        location(loc), format(format), size({x, y}), valid(valid) {

        u64 endLoc = (u64)loc + sizeInBytes();
        // Check if start and end are valid here
        range = Interval<u32>(loc, (u32)endLoc);
    }

    bool hasStencil() {
        return format == Formats::Depth24Stencil8;
    }

    void allocate() {
        // Create texture for the FBO, setting up filters and the like
        // Reading back the current texture is slow, but allocate calls should be few and far between.
        // If this becomes a bottleneck, we can fix it semi-easily
        auto prevTexture = OpenGL::getTex2D();

        // Internal formats for the texture based on format
        static constexpr std::array<GLenum, 4> internalFormats = {
            GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT24, GL_DEPTH24_STENCIL8
        };

        // Format of the texture
        static constexpr std::array<GLenum, 4> formats = {
            GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, GL_DEPTH_STENCIL
        };

        static constexpr std::array<GLenum, 4> types = {
            GL_UNSIGNED_SHORT, GL_UNSIGNED_INT, GL_UNSIGNED_INT, GL_UNSIGNED_INT_24_8
        };

        auto internalFormat = internalFormats[(int)format];
        auto fmt = formats[(int)format];
        auto type = types[(int)format];

        texture.createDSTexture(size.x(), size.y(), internalFormat, fmt, nullptr, type, GL_TEXTURE_2D);
        texture.bind();
        texture.setMinFilter(OpenGL::Nearest);
        texture.setMagFilter(OpenGL::Nearest);
        
        glBindTexture(GL_TEXTURE_2D, prevTexture);
    }

    void free() {
        valid = false;
        printf("Make this depth buffer free itself\n");
    }

    bool matches(DepthBuffer& other) {
        return location == other.location && format == other.format &&
            size.x() == other.size.x() && size.y() == other.size.y();
    }

    // Size occupied by each pixel in bytes
    size_t sizePerPixel() {
        switch (format) {
            case Formats::Depth16: return 2;
            case Formats::Depth24: return 3;
            case Formats::Depth24Stencil8: return 4;

            default: return 1; // Invalid format
        }
    }

    size_t sizeInBytes() {
        return (size_t)size.x() * (size_t)size.y() * sizePerPixel();
    }
};