add background for F3 text, fix single-channel texture display

internal/igwrap/backend/render.go

@@ -87,7 +87,7 @@ func CreateFontsTexture() {
 	)
 
 	io.Fonts().SetTextureID(imgui.TextureID(tex))
-	igwrap.SetTextureFlag(tex, igwrap.TextureFlag_Red)
+	igwrap.SetTextureFlag(tex, igwrap.TextureFlag_ImGUIFont)
 
 	gl.BindTexture(gl.TEXTURE_2D, uint32(lastTexture))
 }

internal/igwrap/backend/shader.frag

@@ -6,7 +6,8 @@
 #define FLAG_ALPHA  (1<<3)
 #define FLAG_COLORS (FLAG_RED | FLAG_GREEN | FLAG_BLUE | FLAG_ALPHA)
 
-#define FLAG_LINEAR (1<<4)
+#define FLAG_LINEAR     (1<<4)
+#define FLAG_IMGUI_FONT (1<<5)
 
 uniform sampler2D tex;
 uniform int flags;
@@ -19,8 +20,10 @@ out vec4 outputColor;
 const float gamma = 2.2;
 
 void main() {
-	if ((flags & FLAG_COLORS) == FLAG_RED) {
+	if ((flags & FLAG_IMGUI_FONT) != 0) {
 		outputColor = vec4(fragColor.rgb, fragColor.a * texture(tex, fragUV.st).r);
+	} else if ((flags & FLAG_COLORS) == FLAG_RED) {
+		outputColor = vec4(vec3(texture(tex, fragUV.st).r), 1);
 	} else {
 		vec4 color = texture(tex, fragUV.st);
 		if ((flags & FLAG_LINEAR) != 0)

internal/igwrap/convert.go

@@ -15,11 +15,21 @@ func Color(r, g, b, a uint8) imgui.Vec4 {
 	}
 }
 
+// PackedColor converts RGBA to imgui.PackedColor.
+func PackedColor(color itype.Vec4f) imgui.PackedColor {
+	return imgui.PackedColorFromVec4(Vec4(color))
+}
+
 // Vec2 converts itype.Vec2f to imgui.Vec2.
 func Vec2(v itype.Vec2f) imgui.Vec2 {
 	return imgui.Vec2{X: v[0], Y: v[1]}
 }
 
+// Vec2f converts imgui.Vec2 to itype.Vec2f.
+func Vec2f(v imgui.Vec2) itype.Vec2f {
+	return itype.Vec2f{v.X, v.Y}
+}
+
 // Vec4 converts itype.Vec4f to imgui.Vec4.
 func Vec4(v itype.Vec4f) imgui.Vec4 {
 	return imgui.Vec4{X: v[0], Y: v[1], Z: v[2], W: v[3]}

internal/igwrap/imagewrap.go

@@ -46,7 +46,8 @@ const (
 	TextureFlag_Blue                          // Renders the Blue channel.
 	TextureFlag_Alpha                         // Renders the Alpha channel.
 
-	TextureFlag_Linear // Linear source data, requires gamma correction.
+	TextureFlag_Linear    // Linear source data, requires gamma correction.
+	TextureFlag_ImGUIFont // This is a font texture from ImGUI, with a single red channel.
 
 	TextureFlag_RGB  = TextureFlag_Red | TextureFlag_Green | TextureFlag_Blue
 	TextureFlag_RGBA = TextureFlag_Red | TextureFlag_Green | TextureFlag_Blue | TextureFlag_Alpha

internal/igwrap/wrap.go

@@ -21,6 +21,20 @@ func Text(format string, a ...interface{}) {
 	imgui.Text(fmt.Sprintf(format, a...))
 }
 
+// TextBackground wraps imgui.Text to create a
+// shortcut for fmt.Sprintf.
+//
+// It also fills the background of the text with the given color.
+func TextBackground(color itype.Vec4f, padding itype.Vec2f, format string, a ...interface{}) {
+	text := fmt.Sprintf(format, a...)
+	orig := imgui.CursorScreenPos()
+	size := imgui.CalcTextSize(text, false, 0)
+	halfpad := padding.Multiply(0.5)
+	imgui.BackgroundDrawList().AddRectFilledV(orig.Minus(Vec2(halfpad)), orig.Plus(size).Plus(Vec2(halfpad)), PackedColor(color), 0, 0)
+
+	imgui.Text(text)
+}
+
 // Begin wraps imgui.BeginV to create a
 // easy-to-use and intuitive interface.
 //