set filename,width,height and drift from the command line

Signed-off-by: Jeff Carr <[email protected]>

community/seascape-shader/Makefile

@@ -0,0 +1,18 @@
+# go get -u github.com/faiface/pixel-examples
+# cd ~/go/src/github.com/faiface/pixel-examples/community/seascape-shader
+
+all:
+ go build
+ ./seascape-shader
+
+push:
+ git pull
+ git add --all
+ -git commit -a -s
+ git push
+
+update:
+ git pull
+
+diff:
+ git diff

community/seascape-shader/README.md

@@ -8,6 +8,15 @@ Looking at the seascape.glsl example you can see **iResolution**, **iTime** and
 
 These are commonly needed to be exposed because these things are coming from outside and needs to be updated. Any other variable you need to have changed/updated from code can be exposed like those.
 
+## Command line arguments
+
+```
+./seascape-shader -h # will show you the command line options
+
+./seascape-shader -filename ./shaders/seascape.glsl # Seascape
+./seascape-shader -filename ./shaders/planetfall.glsl # Planet Fall demo
+```
+
 ## Exposing variables
 
 How to expose variables like this?

community/seascape-shader/seascape.go

@@ -2,6 +2,7 @@ package main
 
 import (
  "time"
+ "log"
 
  "github.com/go-gl/mathgl/mgl32"
 
@@ -10,11 +11,25 @@ import (
  "golang.org/x/image/colornames"
 )
 
+import "flag"
+import "os"
+
+var (
+ version string
+ race bool
+ debug = os.Getenv("BUILDDEBUG") != ""
+ filename string
+ width int
+ height int
+ timeout = "120s"
+ uDrift float32
+)
+
 func run() {
  // Set up window configs
  cfg := pixelgl.WindowConfig{ // Default: 1024 x 768
- Title: "Golang Seascape from Shadertoy",
- Bounds: pixel.R(0, 0, 1024, 768),
+ Title: "Golang GLSL",
+ Bounds: pixel.R(0, 0, float64(width), float64(height)),
  VSync: true,
  }
 
@@ -30,8 +45,9 @@ func run() {
 
  // I am putting all shader example initializing stuff here for
  // easier reference to those learning to use this functionality
- fragSource, err := LoadFileToString("shaders/seascape.glsl")
- // fragSource, err := LoadFileToString("shaders/planetfall.glsl")
+
+ fragSource, err := LoadFileToString(filename)
+
  if err != nil {
  panic(err)
  }
@@ -46,6 +62,7 @@ func run() {
  "uResolution", &uResolution,
  "uTime", &uTime,
  "uMouse", &uMouse,
+ "uDrift", &uDrift,
  )
 
  canvas.SetFragmentShader(fragSource)
@@ -69,6 +86,27 @@ func run() {
 
 }
 
+func parseFlags() {
+ flag.StringVar (&version, "version", "v0.1", "Set compiled in version string")
+ flag.StringVar (&filename, "filename", "shaders/seascape.glsl", "path to GLSL file")
+ flag.IntVar (&width, "width", 1024, "Width of the OpenGL Window")
+ flag.IntVar (&height, "height", 768, "Height of the OpenGL Window")
+ var tmp float64
+ flag.Float64Var (&tmp, "drift", 0.01, "Speed of the gradual camera drift")
+ flag.BoolVar (&race, "race", race, "Use race detector")
+
+ // this parses the arguements
+ flag.Parse()
+
+ uDrift = float32(tmp)
+ log.Println("width=",width)
+ log.Println("height=",height)
+ log.Println("uDrift=",uDrift)
+
+}
+
 func main() {
+ parseFlags()
+
  pixelgl.Run(run)
 }

community/seascape-shader/shaders/seascape.glsl

@@ -10,6 +10,9 @@ uniform vec2 uResolution;
 uniform float uTime;
 uniform vec4 uMouse;
 
+// This is how much you are drifting around. Zero means it only moves when the mouse moves
+uniform float uDrift;
+
 out vec4 fragColor;
 
 const int NUM_STEPS = 8;
@@ -167,7 +170,7 @@ void main()
  vec2 uv = gl_FragCoord.xy / uResolution.xy;
  uv = uv * 2.0 - 1.0;
  uv.x *= uResolution.x / uResolution.y;
- float time = uTime * 0.3 + uMouse.x*0.01;
+ float time = uTime * uDrift * 5 + uMouse.x*0.01;
 
  // ray
  vec3 ang = vec3(sin(time*3.0)*0.1,sin(time)*0.2+0.3,time);