Ritchie Cunningham
c3316b3da1
Overhauls text rendering to improve performance. Renderer was really ineffient, sending a separate GPU draw call for every character rendered. This created a bottleneck, especially with text-heavy UI stuff like the wallpaper. - The 'TextRenderer' now generates a single texture atlas for all font glyhs on load so all characters share a single texture. - 'begin()' / 'flush()' was added to the 'TextRenderer'. Calls to 'render_text' now buffer vertex data (position, texture coords, colour) instead of drawing immediately. A single 'flush()' call at the end of a pass draws all buffered text in one draw call. - A simple batching introduced some shitty visual layering bugs. to solve this, a staged flushing architecture has been implemented. Each logical UI component is now responsible for managing its own rendering passes, beginning and flushing text batches as needed to ensure correct back-to-front layering.
48 lines
1.1 KiB
C++
48 lines
1.1 KiB
C++
#pragma once
|
|
|
|
#include <ft2build.h>
|
|
#include <vector>
|
|
#include FT_FREETYPE_H
|
|
|
|
#include "shader.h"
|
|
#include "types.h"
|
|
|
|
struct TextVertex {
|
|
float x, y, s, t, r, g, b;
|
|
};
|
|
|
|
/* State of a single charactrer glyph. */
|
|
struct character {
|
|
int size[2];
|
|
int bearing[2];
|
|
unsigned int advance;
|
|
float tx, ty; /* x and y offset of glyph in texture atlas. */
|
|
float tw, th; /* width and height of glyph in texture atlas. */
|
|
};
|
|
|
|
const int MAX_GLYPHS_PER_BATCH = 10000;
|
|
const int VERTICES_PER_GLYPH = 6;
|
|
const int MAX_VERTICES = MAX_GLYPHS_PER_BATCH * VERTICES_PER_GLYPH;
|
|
|
|
class TextRenderer {
|
|
public:
|
|
TextRenderer(unsigned int screen_width, unsigned int screen_height);
|
|
~TextRenderer(void);
|
|
|
|
void load_font(const char* font_path, unsigned int font_size);
|
|
void render_text(const char* text, float x, float y, const Color& color);
|
|
float get_text_width(const char* text, float scale);
|
|
|
|
void begin(void);
|
|
void flush(void);
|
|
|
|
|
|
private:
|
|
Shader* _txt_shader;
|
|
unsigned int _vao, _vbo;
|
|
unsigned int _atlas_texture_id;
|
|
character _chars[128];
|
|
std::vector<TextVertex> _vertices;
|
|
float _projecton[16];
|
|
};
|