vertex-array.cpp

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/*
 * Copyright (C) 2023  Christopher J. Howard
 *
 * This file is part of Antkeeper source code.
 *
 * Antkeeper source code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Antkeeper source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <engine/gl/vertex-array.hpp>
#include <engine/gl/opengl/gl-format-lut.hpp>
#include <glad/gl.h>
#include <stdexcept>
 
namespace {
    
    // 0 = unscaled, 1 = normalized, 2 = scaled
    static constexpr std::uint8_t format_scale_lut[] =
    {
        0, // undefined
        1, // r4g4_unorm_pack8
        1, // r4g4b4a4_unorm_pack16
        1, // b4g4r4a4_unorm_pack16
        1, // r5g6b5_unorm_pack16
        1, // b5g6r5_unorm_pack16
        1, // r5g5b5a1_unorm_pack16
        1, // b5g5r5a1_unorm_pack16
        1, // a1r5g5b5_unorm_pack16
        1, // r8_unorm
        1, // r8_snorm
        2, // r8_uscaled
        2, // r8_sscaled
        0, // r8_uint
        0, // r8_sint
        0, // r8_srgb
        1, // r8g8_unorm
        1, // r8g8_snorm
        2, // r8g8_uscaled
        2, // r8g8_sscaled
        0, // r8g8_uint
        0, // r8g8_sint
        0, // r8g8_srgb
        1, // r8g8b8_unorm
        1, // r8g8b8_snorm
        2, // r8g8b8_uscaled
        2, // r8g8b8_sscaled
        0, // r8g8b8_uint
        0, // r8g8b8_sint
        0, // r8g8b8_srgb
        1, // b8g8r8_unorm
        1, // b8g8r8_snorm
        2, // b8g8r8_uscaled
        2, // b8g8r8_sscaled
        0, // b8g8r8_uint
        0, // b8g8r8_sint
        0, // b8g8r8_srgb
        1, // r8g8b8a8_unorm
        1, // r8g8b8a8_snorm
        2, // r8g8b8a8_uscaled
        2, // r8g8b8a8_sscaled
        0, // r8g8b8a8_uint
        0, // r8g8b8a8_sint
        0, // r8g8b8a8_srgb
        1, // b8g8r8a8_unorm
        1, // b8g8r8a8_snorm
        2, // b8g8r8a8_uscaled
        2, // b8g8r8a8_sscaled
        0, // b8g8r8a8_uint
        0, // b8g8r8a8_sint
        0, // b8g8r8a8_srgb
        1, // a8b8g8r8_unorm_pack32
        1, // a8b8g8r8_snorm_pack32
        2, // a8b8g8r8_uscaled_pack32
        2, // a8b8g8r8_sscaled_pack32
        0, // a8b8g8r8_uint_pack32
        0, // a8b8g8r8_sint_pack32
        0, // a8b8g8r8_srgb_pack32
        1, // a2r10g10b10_unorm_pack32
        1, // a2r10g10b10_snorm_pack32
        2, // a2r10g10b10_uscaled_pack32
        2, // a2r10g10b10_sscaled_pack32
        0, // a2r10g10b10_uint_pack32
        0, // a2r10g10b10_sint_pack32
        1, // a2b10g10r10_unorm_pack32
        1, // a2b10g10r10_snorm_pack32
        2, // a2b10g10r10_uscaled_pack32
        2, // a2b10g10r10_sscaled_pack32
        0, // a2b10g10r10_uint_pack32
        0, // a2b10g10r10_sint_pack32
        1, // r16_unorm
        1, // r16_snorm
        2, // r16_uscaled
        2, // r16_sscaled
        0, // r16_uint
        0, // r16_sint
        0, // r16_sfloat
        1, // r16g16_unorm
        1, // r16g16_snorm
        2, // r16g16_uscaled
        2, // r16g16_sscaled
        0, // r16g16_uint
        0, // r16g16_sint
        0, // r16g16_sfloat
        1, // r16g16b16_unorm
        1, // r16g16b16_snorm
        2, // r16g16b16_uscaled
        2, // r16g16b16_sscaled
        0, // r16g16b16_uint
        0, // r16g16b16_sint
        0, // r16g16b16_sfloat
        1, // r16g16b16a16_unorm
        1, // r16g16b16a16_snorm
        2, // r16g16b16a16_uscaled
        2, // r16g16b16a16_sscaled
        0, // r16g16b16a16_uint
        0, // r16g16b16a16_sint
        0, // r16g16b16a16_sfloat
        0, // r32_uint
        0, // r32_sint
        0, // r32_sfloat
        0, // r32g32_uint
        0, // r32g32_sint
        0, // r32g32_sfloat
        0, // r32g32b32_uint
        0, // r32g32b32_sint
        0, // r32g32b32_sfloat
        0, // r32g32b32a32_uint
        0, // r32g32b32a32_sint
        0, // r32g32b32a32_sfloat
        0, // r64_uint
        0, // r64_sint
        0, // r64_sfloat
        0, // r64g64_uint
        0, // r64g64_sint
        0, // r64g64_sfloat
        0, // r64g64b64_uint
        0, // r64g64b64_sint
        0, // r64g64b64_sfloat
        0, // r64g64b64a64_uint
        0, // r64g64b64a64_sint
        0, // r64g64b64a64_sfloat
        0, // b10g11r11_ufloat_pack32
        0, // e5b9g9r9_ufloat_pack32
        1, // d16_unorm
        1, // x8_d24_unorm_pack32
        0, // d32_sfloat
        0, // s8_uint
        1, // d16_unorm_s8_uint
        1, // d24_unorm_s8_uint
        0, // d32_sfloat_s8_uint
        1, // bc1_rgb_unorm_block,
        0, // bc1_rgb_srgb_block,
        1, // bc1_rgba_unorm_block,
        0, // bc1_rgba_srgb_block,
        1, // bc2_unorm_block,
        0, // bc2_srgb_block,
        1, // bc3_unorm_block,
        0, // bc3_srgb_block,
        1, // bc4_unorm_block,
        1, // bc4_snorm_block,
        1, // bc5_unorm_block,
        1, // bc5_snorm_block,
        2, // bc6h_ufloat_block,
        2, // bc6h_sfloat_block,
        1, // bc7_unorm_block,
        0, // bc7_srgb_block,
        1, // etc2_r8g8b8_unorm_block,
        0, // etc2_r8g8b8_srgb_block,
        1, // etc2_r8g8b8a1_unorm_block,
        0, // etc2_r8g8b8a1_srgb_block,
        1, // etc2_r8g8b8a8_unorm_block,
        0, // etc2_r8g8b8a8_srgb_block,
        1, // eac_r11_unorm_block,
        1, // eac_r11_snorm_block,
        1, // eac_r11g11_unorm_block,
        1, // eac_r11g11_snorm_block,
        1, // astc_4x4_unorm_block,
        0, // astc_4x4_srgb_block,
        1, // astc_5x4_unorm_block,
        0, // astc_5x4_srgb_block,
        1, // astc_5x5_unorm_block,
        0, // astc_5x5_srgb_block,
        1, // astc_6x5_unorm_block,
        0, // astc_6x5_srgb_block,
        1, // astc_6x6_unorm_block,
        0, // astc_6x6_srgb_block,
        1, // astc_8x5_unorm_block,
        0, // astc_8x5_srgb_block,
        1, // astc_8x6_unorm_block,
        0, // astc_8x6_srgb_block,
        1, // astc_8x8_unorm_block,
        0, // astc_8x8_srgb_block,
        1, // astc_10x5_unorm_block,
        0, // astc_10x5_srgb_block,
        1, // astc_10x6_unorm_block,
        0, // astc_10x6_srgb_block,
        1, // astc_10x8_unorm_block,
        0, // astc_10x8_srgb_block,
        1, // astc_10x10_unorm_block,
        0, // astc_10x10_srgb_block,
        1, // astc_12x10_unorm_block,
        0, // astc_12x10_srgb_block,
        1, // astc_12x12_unorm_block,
        0, // astc_12x12_srgb_block
    };
}
 
namespace gl {
 
vertex_array::vertex_array(std::span<const vertex_input_attribute> attributes)
{
    m_attributes.assign(attributes.begin(), attributes.end());
    
    glCreateVertexArrays(1, &m_gl_named_array);
    
    for (const auto& attribute: m_attributes)
    {
        // Enable attribute
        glEnableVertexArrayAttrib(m_gl_named_array, static_cast<GLuint>(attribute.location));
        
        // Set attribute vertex binding index
        glVertexArrayAttribBinding
        (
            m_gl_named_array,
            static_cast<GLuint>(attribute.location),
            static_cast<GLuint>(attribute.binding)
        );
        
        const auto format_index = std::to_underlying(attribute.format);
        const auto gl_base_format = gl_format_lut[format_index][1];
        const auto gl_type = gl_format_lut[format_index][2];
        const auto format_scale = format_scale_lut[format_index];
        
        // Determine number of values per vertex
        GLint gl_size;
        switch (gl_base_format)
        {
            case GL_RED:
            case GL_RED_INTEGER:
            case GL_DEPTH_COMPONENT:
            case GL_STENCIL_INDEX:
                gl_size = 1;
                break;
            
            case GL_RG:
            case GL_RG_INTEGER:
            case GL_DEPTH_STENCIL:
                gl_size = 2;
                break;
            
            case GL_BGR:
            case GL_BGR_INTEGER:
            case GL_RGB:
            case GL_RGB_INTEGER:
                gl_size = 3;
                break;
            
            case GL_BGRA:
            case GL_BGRA_INTEGER:
            case GL_RGBA:
            case GL_RGBA_INTEGER:
                gl_size = 4;
                break;
            
            default:
                gl_size = 0;
                break;
        }
        
        if (gl_size == 0 || gl_type == 0)
        {
            throw std::invalid_argument("Vertex input attribute has unsupported format.");
        }
        
        if (format_scale > 0 || gl_type == GL_FLOAT || gl_type == GL_HALF_FLOAT)
        {
            glVertexArrayAttribFormat
            (
                m_gl_named_array,
                static_cast<GLuint>(attribute.location),
                gl_size,
                gl_type,
                (format_scale == 1),
                static_cast<GLuint>(attribute.offset)
            );
        }
        else if (gl_type == GL_DOUBLE)
        {
            glVertexArrayAttribLFormat
            (
                m_gl_named_array,
                static_cast<GLuint>(attribute.location),
                gl_size,
                gl_type,
                static_cast<GLuint>(attribute.offset)
            );
        }
        else
        {
            glVertexArrayAttribIFormat
            (
                m_gl_named_array,
                static_cast<GLuint>(attribute.location),
                gl_size,
                gl_type,
                static_cast<GLuint>(attribute.offset)
            );
        }
    }
}
 
vertex_array::vertex_array()
{
    glCreateVertexArrays(1, &m_gl_named_array);
}
 
vertex_array::~vertex_array()
{
    glDeleteVertexArrays(1, &m_gl_named_array);
}
 
} // namespace gl