examples

commit a9a3d1db2af2ca9a43e1884bfda67dfc32afc665
parent c980f07c3d481ee40e06b33b603da5010838b965
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Wed, 26 Jun 2024 23:01:37 +0100

sdl-gl: Load console raster font and draw test string

Diffstat:
M
src/sdl-gl.cpp
 | 
115
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----

1 file changed, 110 insertions(+), 5 deletions(-)
diff --git a/src/sdl-gl.cpp b/src/sdl-gl.cpp
@@ -17,6 +17,9 @@
 #include <random>
 #include <ranges>
 #include <vector>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <err.h>
 
 extern "C" char const* __asan_default_options() { return "detect_leaks=0"; }
 
@@ -279,11 +282,7 @@ void panel::draw() const
 	glEnd();
 }
 
-void draw_UI()
-{
-	panel{50, 50, 99, 49}.draw();
-	panel{50, 100, 99, 49}.draw();
-}
+
 
 void key(SDL_KeyboardEvent& e)
 {
@@ -466,12 +465,118 @@ void init_shape()
 	shape_wireframe = shape_wireframe.subspan(1, shape.size() - 2);
 }
 
+struct psf2
+{
+	unsigned int magic, version, hdr_size, flags, length, g_size, height, width;
+};
+struct font
+{
+	psf2 hdr;
+	GLuint tex;
+	font(char const* filename)
+	{
+		int fds[2];
+		if (pipe(fds))
+			err(1, "pipe");
+		pid_t child = fork();
+		if (child < 0)
+			err(1, "fork");
+		if (!child)
+		{
+			if (dup2(fds[1], 1) == -1)
+				err(1, "dup2");
+			if (close(fds[0]))
+				err(1, "close");
+			if (close(fds[1]))
+				err(1, "close");
+			execlp("gunzip", "gunzip", "--stdout", filename, nullptr);
+			err(1, "execlp");
+		}
+		close(fds[1]);
+
+		if (read(fds[0], &hdr, sizeof(hdr)) != sizeof(hdr))
+			err(1, "read");
+		if (hdr.magic != 0x864AB572)
+			errx(1, "Not a PSF2 file");
+
+		std::vector<unsigned char> storage(hdr.length * hdr.g_size);
+
+		for (ssize_t read = 0; read < (ssize_t)storage.size(); )
+		{
+			int n = ::read(fds[0], storage.data() + read, storage.size() - read);
+			if (n < 0)
+				err(1, "read");
+			if (n == 0)
+				errx(1, "not enough data from font");
+			read += n;
+		}
+		close(fds[0]);
+		assert(wait(nullptr) == child);
+		std::vector<unsigned char> pix(hdr.length * hdr.height * hdr.width);
+
+		for (size_t i = 0; i < pix.size(); ++i)
+			pix[i] = ((storage[i / 8] >> (7 - i % 8)) & 1) * 255;
+
+		glGenTextures(1, &tex);
+		glBindTexture(GL_TEXTURE_2D, tex);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, hdr.width, hdr.height * hdr.length, 0, GL_ALPHA, GL_UNSIGNED_BYTE, pix.data());
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	}
+	screen_coord draw(unsigned char c, screen_coord pos)
+	{
+		screen_coord br_screen{pos.x + (int)hdr.width, pos.y + (int)hdr.height};
+		float text = (float)c / hdr.length;
+		float texb = (float)(c + 1u) / hdr.length;
+		auto tl = window_to_gl(pos);
+		auto tr = window_to_gl({br_screen.x, pos.y});
+		auto bl = window_to_gl({pos.x, br_screen.y});
+		auto br = window_to_gl(br_screen);
+
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		glEnable(GL_BLEND);
+		glEnable(GL_TEXTURE_2D);
+		glBegin(GL_TRIANGLE_STRIP);
+		glTexCoord2f(0,text);
+		glVertex(tl);
+		glTexCoord2f(1,text);
+		glVertex(tr);
+		glTexCoord2f(0,texb);
+		glVertex(bl);
+		glTexCoord2f(1,texb);
+		glVertex(br);
+		glEnd();
+		glDisable(GL_TEXTURE_2D);
+		glDisable(GL_BLEND);
+
+		return br_screen;
+	}
+	screen_coord draw(char const* str, screen_coord pos)
+	{
+		while (*str)
+			pos.x = draw(*str++, pos).x;
+		return pos;
+	}
+};
+
+font* fnt;
+
+void draw_UI()
+{
+	panel{50, 50, 149, 49}.draw();
+	glColor3f(1,1,1);
+	fnt->draw("Hello, World!", {51, 51});
+	panel{50, 100, 149, 49}.draw();
+}
+
 int main()
 {
 	init_shape();
 	mouse_task();
 	initSDL();
 	atexit(SDL_Quit);
+
+	fnt = new font{"/usr/share/kbd/consolefonts/lat9-16.psf.gz"};
+
 	for (;;)
 	{
 		doInput();