helpless/oogabooga/examples/text_rendering.c

int entry(int argc, char **argv) {
	
	window.title = STR("OGB Text Rendering Example");
	window.scaled_width = 1280;
	window.scaled_height = 720;
	window.x = 200;
	window.y = 200;
	window.clear_color = hex_to_rgba(0x6495EDff);
	
	Gfx_Font *font = load_font_from_disk(STR("C:/windows/fonts/arial.ttf"), get_heap_allocator());
	assert(font, "Failed loading arial.ttf");
	
	const u32 font_height = 48;
	
	seed_for_random = rdtsc();
	u64 gunk_seed = get_random();
	
	while (!window.should_close) tm_scope("Frame") {
		reset_temporary_storage();
		
		// Text is easiest to deal with if our projection matches window pixel size, because
		// then the rasterization height will match the screen pixel height (unless scaling).
		// The best way to make the text look good is to draw it at the exact same pixel height
		// as it was rasterized at with no down- or up-scaling.
		// It's fairly common in video games to render the UI with a separate projection for this
		// very reason.
		draw_frame.projection = m4_make_orthographic_projection(window.pixel_width * -0.5, window.pixel_width * 0.5, window.pixel_height * -0.5, window.pixel_height * 0.5, -1, 10);
		
		// Easy drop shadow: Just draw the same text underneath with a slight offset
		draw_text(font, STR("I am text"), font_height, v2(-2, 2), v2(1, 1), COLOR_BLACK);
		draw_text(font, STR("I am text"), font_height, v2(0, 0),  v2(1, 1), COLOR_WHITE);
		
		draw_text(font, tprint("Time: %f", os_get_elapsed_seconds()), font_height, v2(0, 100),  v2(1, 1), COLOR_WHITE);
		
		float now = (float)os_get_elapsed_seconds();
		float animated_x = sin(now*0.1)*(window.width*0.5);
		
		// UTF-8 !
		draw_text(font, STR("Привет"), font_height, v2(animated_x-2, 2), v2(1, 1), COLOR_BLACK);
		draw_text(font, STR("Привет"), font_height, v2(animated_x, 0),  v2(1, 1), COLOR_WHITE);
		
		// New lines are handled when drawing text
		string hello_str = STR("Hello,\nTTTT New line\nAnother line");
		
		// To align/justify text we need to measure it.
		Gfx_Text_Metrics hello_metrics = measure_text(font, hello_str, font_height, v2(1, 1));
		
		// This is where we want the bottom left of the text to be...
		Vector2 bottom_left = v2(-window.width/2+20, -window.height/2+20);
		
		// ... So we have to justify that bottom_left according to text metrics
		Vector2 justified = v2_sub(bottom_left, hello_metrics.functional_pos_min);
		
		// If we wanted to center it:
		// justified = v2_sub(justified, v2_divf(hello_metrics.functional_size, 2));
		
		draw_text(font, hello_str, font_height, justified,  v2(1, 1), COLOR_WHITE);
		
		
		local_persist bool show_bounds = false;
		if (is_key_just_pressed('E')) show_bounds = !show_bounds;
		
		
		string long_text = STR("Jaunty jackrabbits juggle quaint TTT quilts and quirky quinces, \nquickly queuing up for a jubilant, jazzy jamboree in the jungle.\nLorem ipsilum ");
		
		// Generate some random gunk to add to the long text
		u64 n = ((sin(now)+1)/2.0)*100;
		seed_for_random = gunk_seed;
		if (n > 0) {
			string gunk = talloc_string(n);
			for (u64 i = 0; i < n; i++) {
				if (get_random_float32() < 0.2) {
					gunk.data[i] = ' ';
					continue;
				}
				gunk.data[i] = get_random_int_in_range('a', 'z');
			}
			
		 	long_text = string_concat(long_text, gunk, get_temporary_allocator());
		}
		
		if (show_bounds) {
			// Visualize the bounds we get from metrics
			Gfx_Text_Metrics m = measure_text(font, long_text, font_height, v2(1, 1));
			draw_rect(v2_add(v2(-600, -200), m.visual_pos_min), m.visual_size, v4(.1, .1, .1, .2));
			draw_rect(v2_add(v2(-600, -200), m.functional_pos_min), m.functional_size, v4(1, .1, .1, .2));		
		}
		draw_text(font, long_text, font_height, v2(-600, -200),  v2(1, 1), COLOR_WHITE);
		
		// Wrap text and draw each returned line
		string *long_text_wrapped = split_text_to_lines_with_wrapping(long_text, window.width/2*0.9, font, font_height, v2_one, true);
		float32 y = 200;
		for (u64 i = 0; i < growing_array_get_valid_count(long_text_wrapped); i += 1) {
			string line = long_text_wrapped[i];
			Gfx_Font_Metrics m = get_font_metrics(font, font_height);
			
			draw_text(font, line, font_height, v2(-window.width/2+20, y),  v2(1, 1), COLOR_WHITE);
			
			y -= m.new_line_offset;
		}
		
		os_update();
		gfx_update();
		
	}
	
	return 0;
}