A lot of work

* moved all ugui code to lib/ugui.c3l and made it a library/module
* started work on a sdl3 renderer, with shaders etc
* added the new sdl3.c3l library as a dependency
* makefile is for the renderer

resources/shaders/source/font.vert.glsl

@@ -0,0 +1,26 @@
+#version 330 core
+
+// viewsize.x = viewport width in pixels; viewsize.y = viewport height in pixels
+uniform ivec2 viewsize;
+uniform ivec2 texturesize;
+
+// both position and and uv are in pixels, they where converted to floats when 
+// passed to the shader
+layout(location = 0) in vec2 position;
+layout(location = 1) in vec2 txcoord;
+
+out vec2 uv;
+
+void main()
+{
+	vec2 v = vec2(float(viewsize.x), float(viewsize.y));
+	
+//	vec2 p = vec2(position.x*2.0f/v.x - 1.0f, position.y*2.0f/v.y - 1.0f);
+	vec2 p = vec2(position.x*2.0/v.x - 1.0, 1.0 - position.y*2.0/v.y);
+	vec4 pos = vec4(p.x, p.y, 0.0f, 1.0f);
+
+	gl_Position = pos;
+	// since the texture is a GL_TEXTURE_RECTANGLE the coordintes do not need to
+	// be normalized
+	uv = vec2(txcoord.x, txcoord.y);
+}