fix font texture switching

text_rendering/main.c

@@ -14,8 +14,10 @@ SDL_Window *win;
 
 void draw(void)
 {
+	static unsigned int frame = 0;
+	printf("frame: %d\n", frame++);
 	ren_clear();
-	if (ren_render_text(str, 0, 0, 100, 50, 20))
+	if (ren_render_text(str, 10, 10, 100, 50, 20))
 		printf("text: %s\n", ren_strerror());
 	ren_render_text("altro font", 200, 40, 300, 300, 40);
 	ren_render_box(100, 300, 50, 50, 0xffff0000);

text_rendering/ren.c

@@ -446,6 +446,7 @@ static int ren_draw_font_stack(int idx)
 {
 	GL(glUseProgram(ren.font_prog))
 	GL(glBindBuffer(GL_ARRAY_BUFFER, ren.font_buffer))
+	GL(glBindTexture(GL_TEXTURE_RECTANGLE, ren.fonts[idx].texture))
 
 	GL(glViewport(0, 0, ren.width, ren.height))
 	// this has caused me some trouble, convert from image coordiates to viewport