Riyyi
3 months ago
12 changed files with 399 additions and 78 deletions
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/*
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* Copyright (C) 2024 Riyyi |
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* |
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* SPDX-License-Identifier: MIT |
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*/ |
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#include <cstddef> // size_t |
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#include <cstdint> // int32_t, uint8_t |
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#include <string_view> |
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#include "glad/glad.h" |
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#include "glm/gtc/type_ptr.hpp" // glm::value_ptr |
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#include "ruc/meta/assert.h" |
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#include "inferno/render/buffer.h" |
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#include "inferno/render/uniformbuffer.h" |
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namespace Inferno { |
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Uniformbuffer::Uniformbuffer(s) |
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{ |
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// Get maximum uniformbuffer bindings the GPU supports
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int32_t maxBindingPoints = 0; |
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glGetIntegerv(GL_MAX_UNIFORM_BUFFER_BINDINGS, &maxBindingPoints); |
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m_maxBindingPoints = static_cast<uint8_t>(maxBindingPoints); |
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} |
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Uniformbuffer::~Uniformbuffer() |
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{ |
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for (const auto& [_, block] : m_blocks) { |
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glDeleteBuffers(1, &block.id); |
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} |
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m_blocks.clear(); |
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} |
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// -----------------------------------------
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void Uniformbuffer::setLayout(std::string_view blockName, uint8_t bindingPoint, const BufferLayout& layout) |
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{ |
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VERIFY(bindingPoint < m_maxBindingPoints, "{} < {}", bindingPoint, m_maxBindingPoints); |
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if (!exists(blockName)) { |
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m_blocks[blockName] = {}; |
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} |
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UniformbufferBlock& block = m_blocks[blockName]; |
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// Example block layout:
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// - mat3
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// - float
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// - vec2
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// - vec2
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// - float
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// Chunks, 4 slots, 4 bytes per slot
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// [x][x][x][ ] #1
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// [x][x][x][ ] #2
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// [x][x][x][ ] #3
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// [x][ ][x][x] #4
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// [x][x][x][ ] #5
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size_t chunk = 0; |
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uint8_t offset = 0; |
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for (auto it = layout.begin(); it != layout.end(); ++it) { |
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BufferElementType type = it->type(); |
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const std::string& name = it->name(); |
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// Calculate offset
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switch (type) { |
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// Scalar 1
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case BufferElementType::Bool: |
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case BufferElementType::Int: |
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case BufferElementType::Uint: |
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case BufferElementType::Float: { |
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// Offset
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block.uniformLocations[name] = (chunk * 16) + (offset * 4); |
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// Jump
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offset += 1; |
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break; |
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} |
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// Scalar 2
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case BufferElementType::Bool2: |
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case BufferElementType::Int2: |
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case BufferElementType::Uint2: |
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case BufferElementType::Vec2: { |
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// Add padding
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if (offset == 1) { |
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offset++; |
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} |
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if (offset == 3) { |
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offset = 0; |
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chunk++; |
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} |
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// Offset
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block.uniformLocations[name] = (chunk * 16) + (offset * 4); |
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// Jump
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offset += 2; |
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break; |
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} |
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// Scalar 3
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case BufferElementType::Bool3: |
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case BufferElementType::Int3: |
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case BufferElementType::Uint3: |
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case BufferElementType::Vec3: { |
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// Add padding
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if (offset != 0) { |
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offset = 0; |
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chunk++; |
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} |
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// Offset
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block.uniformLocations[name] = (chunk * 16) + (offset * 4); |
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// Jump
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offset += 3; |
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break; |
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} |
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// Scalar 4
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case BufferElementType::Bool4: |
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case BufferElementType::Int4: |
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case BufferElementType::Uint4: |
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case BufferElementType::Vec4: { |
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// Add padding
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if (offset != 0) { |
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offset = 0; |
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chunk++; |
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} |
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// Offset
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block.uniformLocations[name] = (chunk * 16) + (offset * 4); |
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// Jump
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offset += 4; |
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break; |
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} |
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// Array types
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case BufferElementType::Mat2: |
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case BufferElementType::Mat3: |
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case BufferElementType::Mat4: { |
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// Add padding
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if (offset != 0) { |
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offset = 0; |
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chunk++; |
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} |
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// Offset
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block.uniformLocations[name] = (chunk * 16) + (offset * 4); |
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// Additional rows
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if (type == BufferElementType::Mat2) { |
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chunk += 1; |
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} |
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else if (type == BufferElementType::Mat3) { |
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chunk += 2; |
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} |
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else { |
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chunk += 3; |
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} |
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// Jump
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offset += 4; |
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break; |
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} |
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// TODO: Implement these types
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case BufferElementType::Double: |
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case BufferElementType::Vec2Double: |
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case BufferElementType::Vec3Double: |
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case BufferElementType::Vec4Double: |
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case BufferElementType::MatDouble2: |
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case BufferElementType::MatDouble3: |
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case BufferElementType::MatDouble4: |
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VERIFY_NOT_REACHED(); |
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case BufferElementType::None: |
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VERIFY_NOT_REACHED(); |
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}; |
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// Overflow slots to next chunk
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if (offset > 3) { |
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offset = 0; |
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chunk++; |
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} |
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} |
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// Pad the end of the buffer
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if (offset != 0) { |
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offset = 0; |
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chunk++; |
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} |
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block.size = chunk * 16; |
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} |
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void Uniformbuffer::create(std::string_view blockName) |
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{ |
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VERIFY(exists(blockName), "uniformbuffer block doesnt exist"); |
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UniformbufferBlock& block = m_blocks[blockName]; |
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if (block.id != 0) { |
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glDeleteBuffers(1, &block.id); |
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} |
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// Allocate buffer
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block.id = UINT_MAX; |
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glGenBuffers(1, &block.id); |
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glBindBuffer(GL_UNIFORM_BUFFER, block.id); |
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glBufferData(GL_UNIFORM_BUFFER, block.size, NULL, GL_DYNAMIC_DRAW); |
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glBindBuffer(GL_UNIFORM_BUFFER, 0); |
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// Bind buffer to binding point
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glBindBufferBase(GL_UNIFORM_BUFFER, block.bindingPoint, block.id); |
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} |
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void Uniformbuffer::setFloat(std::string_view blockName, std::string_view member, glm::mat4 matrix) |
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{ |
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VERIFY(exists(blockName), "uniformbuffer block doesnt exist"); |
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const UniformbufferBlock& block = m_blocks[blockName]; |
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VERIFY(block.uniformLocations.find(member.data()) != block.uniformLocations.end(), |
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"uniformbuffer block member doesnt exist"); |
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// Note: Uniformbuffers are bound to a binding point for the entire pipeline,
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// it remains accessible without needing to rebind it every time
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glBufferSubData(GL_UNIFORM_BUFFER, block.uniformLocations.at(member.data()), sizeof(glm::mat4), glm::value_ptr(matrix)); |
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} |
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} // namespace Inferno
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@ -0,0 +1,90 @@
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/*
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* Copyright (C) 2024 Riyyi |
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* |
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* SPDX-License-Identifier: MIT |
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*/ |
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#include <cstdint> // uint8_t, uint32_t |
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#include <string> |
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#include <string_view> |
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#include <unordered_map> |
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#include "glm/ext/matrix_float4x4.hpp" // glm::mat4 |
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#include "ruc/singleton.h" |
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#include "inferno/render/buffer.h" |
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namespace Inferno { |
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struct UniformbufferBlock { |
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uint32_t id { 0 }; |
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uint32_t size { 0 }; |
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uint8_t bindingPoint { 0 }; |
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std::unordered_map<std::string, uint32_t> uniformLocations {}; |
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}; |
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class Uniformbuffer final : public ruc::Singleton<Uniformbuffer> { // Uniform Buffer Object, UBO
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public: |
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Uniformbuffer(s); |
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~Uniformbuffer(); |
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void setLayout(std::string_view blockName, uint8_t bindingPoint, const BufferLayout& layout); |
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void create(std::string_view blockName); |
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void setFloat(std::string_view blockName, std::string_view member, glm::mat4 matrix); |
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bool exists(std::string_view blockName) const { return m_blocks.find(blockName) != m_blocks.end(); } |
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private: |
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uint8_t m_maxBindingPoints { 0 }; |
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std::unordered_map<std::string_view, UniformbufferBlock> m_blocks; |
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}; |
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} // namespace Inferno
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#if 0 |
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// -----------------------------------------
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// Example usage:
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Uniformbuffer::the().setLayout( |
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"ExampleBlock", 0, |
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{ |
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{ BufferElementType::Mat3, "a" }, |
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{ BufferElementType::Float, "b" }, |
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{ BufferElementType::Vec2, "c" }, |
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{ BufferElementType::Vec2, "d" }, |
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{ BufferElementType::Float, "e" }, |
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}); |
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Uniformbuffer::the().create("ExampleBlock"); |
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#endif |
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// -----------------------------------------
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// Memory alignment of uniform blocks using std140
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//
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// Main points:
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// - Memory is organized into chunks.
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// - A block is at least the size of 1 chunk.
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// - One chunk has 4 slots, 4 bytes per slot.
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// - Can't fit? Move to next chunk.
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//
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// The rules:
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// 1. Scalar (bool, int, uint, float) takes up 1 slot, can appear after anything
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// 2. Vec2 takes up 2 slots, in first or last half of a chunk
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// 3. Vec3 takes up 3 slots, only at the start of a chunk
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// 4. Everything else:
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// - Take up maxumum room
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// - As often as needed
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// - Add padding as needed
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// 5. Mat3 (or any matrix) are treated like arrays
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// 6. Each member of *any* array gets its own chunk
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// TODO: How do double types work?
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// -----------------------------------------
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// References:
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// - https://learnopengl.com/Advanced-OpenGL/Advanced-GLSL
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// - https://www.khronos.org/opengl/wiki/Interface_Block_(GLSL)#Memory_layout
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// - https://www.oreilly.com/library/view/opengl-programming-guide/9780132748445/app09lev1sec2.html (The std140 Layout Rules)
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// - https://www.youtube.com/watch?v=JPvbRko9lBg (WebGL 2: Uniform Buffer Objects)
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