various changes:

- renamed example shaders to .kage
- added --map-* options to map builtin uniforms to custom names
- added ebitengine sample shader with mapping (run `make shader-ebiten`)
- fixed bug: shaders with 0 images are allowed now

.gitignore

@@ -1 +1,2 @@
 releases
+kage-viewer

Makefile

@@ -40,6 +40,12 @@ install: buildlocal
 clean:
 	rm -rf $(tool) coverage.out testdata t/out
 
+shader-destruct: buildlocal
+	./$(tool) -g 32x32 -i example/wall.png -i example/damage.png --map-ticks Time -s example/destruct.kage
+
+shader-ebiten: buildlocal
+	./$(tool) -g 640x480 --map-ticks Time --map-mouse Cursor -s example/ebiten.kage
+
 test: clean
 	mkdir -p t/out
 	go test ./... $(ARGS)

README.md

@@ -61,13 +61,17 @@ Usage: kage-viewer [-vd] [-c <config file>] [-g geom] [-p geom] \
        -i <image0.png> -i <image1.png> -s <shader.kage>
 
 Options:
--c --config   <toml file>     Config file to use (optional)
+-c --config     <toml file>     Config file to use (optional)
--i --image    <png file>      Image to load (multiple times allowed, up to 4)
+-i --image      <png file>      Image to load (multiple times allowed, up to 4)
--s --shader   <kage file>     Shader to run
+-s --shader     <kage file>     Shader to run
--g --geometry <WIDTHxHEIGHT>  Window size
+-g --geometry   <WIDTHxHEIGHT>  Window size
--p --position <XxY>           Position of image0
+-p --position   <XxY>           Position of image0
--d --debug    Show debugging output
+   --map-flag   <name>          Map Flag uniform to <name>
--v --version  Show program version
+   --map-ticks  <name>          Map Flag uniform to <name>
+   --map-slider <name>          Map Flag uniform to <name>
+   --map-mouse  <name>          Map Flag uniform to <name>
+-d --debug                      Show debugging output
+-v --version                    Show program version
 ```
 
 Example usage using the provided example:
@@ -90,9 +94,19 @@ Uniforms supported so far:
   `SPACE` or pusing the left mouse button
 - `var Slider float`: a normalized float value, you can increment it
   with `UP` or `DOWN`
-- `var Ticks int`: the time the game runs (ticks, not seconds!)
+- `var Ticks float`: the time the game runs (ticks, not seconds!)
 - `var Mouse vec2`: the current mouse position
 
+If you want to test an existing shader and don't want to rename the
+uniforms, you can map the ones provided by **kage-viewer** to custom
+names using the `--map-*` options. For example:
+
+```shell
+kage-viewer -g 640x480 --map-ticks Time --map-mouse Cursor examples/shader/default.go
+```
+
+This executes the example shader in the ebitenging source repository.
+
 # Config File
 
 You can use a config file to store your own codes, once you found one

config.go

@@ -32,20 +32,24 @@ import (
 )
 
 const (
-	VERSION string = "0.0.1"
+	VERSION string = "0.0.2"
 	Usage   string = `This is kage-viewer, a shader viewer.
 
 Usage: kage-viewer [-vd] [-c <config file>] [-g geom] [-p geom] \
        -i <image0.png> -i <image1.png> -s <shader.kage>
 
 Options:
--c --config   <toml file>     Config file to use (optional)
+-c --config     <toml file>     Config file to use (optional)
--i --image    <png file>      Image to load (multiple times allowed, up to 4)
+-i --image      <png file>      Image to load (multiple times allowed, up to 4)
--s --shader   <kage file>     Shader to run
+-s --shader     <kage file>     Shader to run
--g --geometry <WIDTHxHEIGHT>  Window size
+-g --geometry   <WIDTHxHEIGHT>  Window size
--p --position <XxY>           Position of image0
+-p --position   <XxY>           Position of image0
--d --debug    Show debugging output
+   --map-flag   <name>          Map Flag uniform to <name>
--v --version  Show program version
+   --map-ticks  <name>          Map Flag uniform to <name>
+   --map-slider <name>          Map Flag uniform to <name>
+   --map-mouse  <name>          Map Flag uniform to <name>
+-d --debug                      Show debugging output
+-v --version                    Show program version
 `
 )
 
@@ -57,6 +61,10 @@ type Config struct {
 	Shader      string   `koanf:"shader"`   // -s
 	Geo         string   `koanf:"geometry"` // -g
 	Posision    string   `koanf:"position"` // -p
+	Flag        string   `koanf:"map-flag"`
+	Ticks       string   `koanf:"map-ticks"`
+	Mouse       string   `koanf:"map-mouse"`
+	Slider      string   `koanf:"map-slider"`
 
 	X, Y, Width, Height int // feed from -g + -p
 }
@@ -64,14 +72,6 @@ type Config struct {
 func InitConfig() (*Config, error) {
 	var kloader = koanf.New(".")
 
-	// Load default values using the confmap provider.
-	/* not needed yet
-	   if err := kloader.Load(confmap.Provider(map[string]interface{}{
-	   }, "."), nil); err != nil {
-	           return nil, fmt.Errorf("failed to load default values into koanf: %w", err)
-	   }
-	*/
-
 	// setup custom usage
 	flagset := flag.NewFlagSet("config", flag.ContinueOnError)
 	flagset.Usage = func() {
@@ -87,6 +87,10 @@ func InitConfig() (*Config, error) {
 	flagset.StringP("position", "p", "0x0", "position of shader")
 	flagset.StringArrayP("image", "i", nil, "image file")
 	flagset.StringP("shader", "s", "", "shader file")
+	flagset.StringP("map-flag", "", "Flag", "map flag uniform")
+	flagset.StringP("map-ticks", "", "Ticks", "map ticks uniform")
+	flagset.StringP("map-mouse", "", "Mouse", "map mouse uniform")
+	flagset.StringP("map-slider", "", "Slider", "map slider uniform")
 
 	if err := flagset.Parse(os.Args[1:]); err != nil {
 		return nil, fmt.Errorf("failed to parse program arguments: %w", err)
@@ -140,10 +144,6 @@ func InitConfig() (*Config, error) {
 }
 
 func SanitiyCheck(conf *Config) error {
-	if len(conf.Image) < 1 {
-		return fmt.Errorf("at least 1 image must be specified")
-	}
-
 	if len(conf.Image) > 4 {
 		return fmt.Errorf("only 4 images can be specified")
 	}

example/destruct.kage

@@ -20,7 +20,7 @@ package main
 
 var Flag int
 var Slider float
-var Time int
+var Time float
 var Mouse vec2
 
 func Fragment(_ vec4, texCoord vec2, _ vec4) vec4 {

example/ebiten.kage

@@ -0,0 +1,33 @@
+// Copyright 2020 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build ignore
+
+//kage:unit pixels
+
+package main
+
+var Time float
+var Cursor vec2
+
+func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
+	pos := (dstPos.xy - imageDstOrigin()) / imageDstSize()
+	pos += Cursor / imageDstSize() / 4
+	clr := 0.0
+	clr += sin(pos.x*cos(Time/15)*80) + cos(pos.y*cos(Time/15)*10)
+	clr += sin(pos.y*sin(Time/10)*40) + cos(pos.x*sin(Time/25)*40)
+	clr += sin(pos.x*sin(Time/5)*10) + sin(pos.y*sin(Time/35)*80)
+	clr *= sin(Time/10) * 0.5
+	return vec4(clr, clr*0.5, sin(clr+Time/3)*0.75, 1)
+}

game.go

@@ -135,10 +135,10 @@ func (game *Game) Draw(screen *ebiten.Image) {
 	mousex, mousey := ebiten.CursorPosition()
 
 	op.Uniforms = map[string]any{
-		"Flag":   game.Flag,
+		game.Conf.Flag:   game.Flag,
-		"Slider": game.Slider,
+		game.Conf.Slider: game.Slider,
-		"Ticks":  game.Ticks,
+		game.Conf.Ticks:  float64(game.Ticks) / 60,
-		"Mouse":  []float64{float64(mousex), float64(mousey)},
+		game.Conf.Mouse:  []float64{float64(mousex), float64(mousey)},
 	}
 
 	copy(op.Images[:3], game.Images)