[nostalgia] Start on new TileSheetEditor

src/nostalgia/core/studio/tilesheetpixelgrid.cpp

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2016 - 2021 Gary Talent (gary@drinkingtea.net). All rights reserved.
+ */
+
+#include <nostalgia/core/consts.hpp>
+#include "tilesheetpixelgrid.hpp"
+
+namespace nostalgia::core {
+
+ox::Error TileSheetGrid::buildShader() noexcept {
+	const auto pixelLineVshad = ox::sfmt(VShad, glutils::GlslVersion);
+	const auto pixelLineFshad = ox::sfmt(FShad, glutils::GlslVersion);
+	const auto pixelLineGshad = ox::sfmt(GShad, glutils::GlslVersion);
+	return glutils::buildShaderProgram(pixelLineVshad, pixelLineFshad, pixelLineGshad).moveTo(&m_shader);
+}
+
+void TileSheetGrid::draw(bool update) noexcept {
+	glUseProgram(m_shader);
+	glBindVertexArray(m_bufferSet.vao);
+	if (update) {
+		glutils::sendVbo(m_bufferSet);
+	}
+	glDrawElements(GL_POINTS, static_cast<GLsizei>(m_bufferSet.elements.size()), GL_UNSIGNED_INT, nullptr);
+}
+
+void TileSheetGrid::initBufferSet(const NostalgiaGraphic &img) noexcept {
+	// vao
+	m_bufferSet.vao = glutils::generateVertexArrayObject();
+	glBindVertexArray(m_bufferSet.vao);
+	// vbo & ebo
+	m_bufferSet.vbo = glutils::generateBuffer();
+	m_bufferSet.ebo = glutils::generateBuffer();
+	setBufferObjects(img, &m_bufferSet);
+	glutils::sendVbo(m_bufferSet);
+	glutils::sendEbo(m_bufferSet);
+	// vbo layout
+	const auto pt1Attr = static_cast<GLuint>(glGetAttribLocation(m_shader, "vPt1"));
+	glEnableVertexAttribArray(pt1Attr);
+	glVertexAttribPointer(pt1Attr, 2, GL_FLOAT, GL_FALSE, VertexVboRowLength * sizeof(float), nullptr);
+	const auto pt2Attr = static_cast<GLuint>(glGetAttribLocation(m_shader, "vPt2"));
+	glEnableVertexAttribArray(pt2Attr);
+	glVertexAttribPointer(pt2Attr, 2, GL_FLOAT, GL_FALSE, VertexVboRowLength * sizeof(float),
+	                      reinterpret_cast<void*>(2 * sizeof(float)));
+}
+
+void TileSheetGrid::setBufferObject(unsigned vertexRow, common::Point pt1, common::Point pt2, float *vbo, GLuint *ebo) noexcept {
+	const auto ps = pixelSize();
+	const auto x1 = static_cast<float>(pt1.x) * ps.x;
+	const auto y1 = static_cast<float>(pt1.y) * ps.y;
+	const auto x2 = static_cast<float>(pt2.x) * ps.x;
+	const auto y2 = static_cast<float>(pt2.y) * ps.y;
+	// don't worry, these memcpys gets optimized to something much more ideal
+	const float vertices[VertexVboLength] = {x1, y1, x2, y2};
+	memcpy(vbo, vertices, sizeof(vertices));
+	const GLuint elms[VertexEboLength] = {vertexRow};
+	memcpy(ebo, elms, sizeof(elms));
+}
+
+void TileSheetGrid::setBufferObjects(const NostalgiaGraphic &img, glutils::BufferSet *bg) noexcept {
+	const auto set = [bg](unsigned i, common::Point pt1, common::Point pt2) {
+		const auto vbo = &bg->vertices[i * VertexVboLength];
+		const auto ebo = &bg->elements[i * VertexEboLength];
+		setBufferObject(i * VertexVboRows, pt1, pt2, vbo, ebo);
+	};
+	// set buffer lengths
+	const auto width = img.columns * TileWidth;
+	const auto height = img.rows * TileHeight;
+	const auto tiles = static_cast<unsigned>(width * height);
+	m_bufferSet.vertices.resize(tiles * VertexVboLength);
+	m_bufferSet.elements.resize(tiles * VertexEboLength);
+	// set buffers
+	auto i = 0ull;
+	for (auto x = 0; x < img.columns; ++x) {
+		set(0, {x, 0}, {x, img.rows});
+		++i;
+	}
+	for (auto y = 0; y < img.rows; ++y) {
+		set(0, {0, y}, {img.columns, y});
+		++i;
+	}
+}
+
+ImVec2 TileSheetGrid::pixelSize() noexcept {
+	const auto [sw, sh] = ImGui::GetContentRegionAvail();
+	constexpr float ymod = 0.35f / 10.0f;
+	const auto xmod = ymod * sh / sw;
+	return {xmod, ymod};
+}
+
+}