init

engine/include/hd2d/Texture.h

@@ -0,0 +1,68 @@
+#pragma once
+#include "hd2d/GL.h"
+
+#include <glm/glm.hpp>
+#include <string>
+#include <vector>
+
+namespace hd2d {
+
+struct Image {
+    int width = 0, height = 0;
+    std::vector<unsigned char> rgba;  // row 0 = bottom (GL convention)
+};
+
+// Loads an RGBA8 image flipped to GL orientation. Colors of fully transparent
+// pixels are replaced with their nearest opaque neighbour so that filtering
+// never bleeds dark fringes into sprite edges.
+bool loadImage(const std::string& path, Image& out);
+// Decodes PNG bytes from memory. glTF images use flipY = false (their UV
+// origin is top-left, which matches GL when rows are uploaded unflipped).
+bool decodeImage(const unsigned char* data, size_t size, Image& out, bool flipY);
+
+// sRGB pixel-art texture. Sampled with "sharp bilinear" in shaders, so it uses
+// linear filtering with mipmaps rather than GL_NEAREST.
+class Texture {
+public:
+    Texture() = default;
+    Texture(const Texture&) = delete;
+    Texture& operator=(const Texture&) = delete;
+    Texture(Texture&& o) noexcept { *this = std::move(o); }
+    Texture& operator=(Texture&& o) noexcept;
+    ~Texture();
+
+    bool load(const std::string& path, bool repeat = false);
+    bool create(const Image& image, bool repeat = false, float anisotropy = 1.0f);
+    void bind(GLuint unit) const { glBindTextureUnit(unit, id_); }
+
+    GLuint id() const { return id_; }
+    glm::ivec2 size() const { return {width_, height_}; }
+    // UV-space rectangle (minX, minY, maxX, maxY) of pixels with alpha >= 128.
+    // Billboards use minY to plant the visible feet on the ground.
+    glm::vec4 opaqueBounds() const { return opaqueBounds_; }
+
+private:
+    GLuint id_ = 0;
+    int width_ = 0, height_ = 0;
+    glm::vec4 opaqueBounds_{0, 0, 1, 1};
+};
+
+// 2D array of equally sized sRGB layers (terrain materials).
+class TextureArray {
+public:
+    TextureArray() = default;
+    TextureArray(const TextureArray&) = delete;
+    TextureArray& operator=(const TextureArray&) = delete;
+    ~TextureArray();
+
+    bool load(const std::vector<std::string>& paths);
+    void bind(GLuint unit) const { glBindTextureUnit(unit, id_); }
+    glm::ivec2 size() const { return {width_, height_}; }
+    int layers() const { return layers_; }
+
+private:
+    GLuint id_ = 0;
+    int width_ = 0, height_ = 0, layers_ = 0;
+};
+
+}  // namespace hd2d