go constants inserted into generated glsl

makes code clearer and less likely to be wrong

Author: JetSetIlly

gui/crt/shaders/constants.go

@@ -0,0 +1,35 @@
+// This file is part of Gopher2600.
+//
+// Gopher2600 is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Gopher2600 is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Gopher2600.  If not, see <https://www.gnu.org/licenses/>.
+
+package shaders
+
+// These constants are used by both Go and GLSL. It is inserted into the GLSL
+// by then "go generate" process
+
+// List of valid ImageTypes.
+const (
+	GUI int32 = iota
+	DebugScr
+	Overlay
+	PlayScr
+	PrefsCRT
+)
+
+// List of valid DrawModes.
+const (
+	NoCursor int32 = iota
+	Cursor
+	LateCursor
+)

gui/crt/shaders/generator/fragment.glsl

@@ -1,5 +1,8 @@
+// this file requires some constant values to be defined above this line before
+// being compiled. should be included during the "go generate" process
+
 uniform int ImageType;
-uniform int DrawMode; // 0 == running; 1 = show drawing; 2 = "goto coords"
+uniform int DrawMode; 
 uniform int Cropped; // false <= 0; true > 0
 uniform vec2 ScreenDim;
 uniform vec2 CropScreenDim;
@@ -52,13 +55,13 @@ float gold_noise(in vec2 xy){
 void main()
 {
 	// imgui texture
-	if (ImageType == 0) {
+	if (ImageType == GUI) {
 		Out_Color = vec4(Frag_Color.rgb, Frag_Color.a * texture(Texture, Frag_UV.st).r);
 		return;
 	}
 
 	// if this is the overlay texture then we're done
-	if (ImageType == 2) {
+	if (ImageType == Overlay) {
 		Out_Color = Frag_Color * texture(Texture, Frag_UV.st);
 		return;
 	}
@@ -77,7 +80,7 @@ void main()
 	float texelY;
 
 	// debug tv screen texture
-	if (ImageType == 1) {
+	if (ImageType == DebugScr) {
 		if (Cropped > 0) {
 			texelX = ScalingX / CropScreenDim.x;
 			texelY = ScalingY / CropScreenDim.y;
@@ -120,9 +123,8 @@ void main()
 			}
 		}
 
-		// when DrawMode is greater than 0 then there's some additional image
-		// processing we need to perform
-		if (DrawMode == 1) {
+		// when DrawMode is Cursor then there is some additional processing we need to perform
+		if (DrawMode == Cursor) {
 			// draw cursor if pixel is at the last x/y position
 			if (lastY >= 0 && lastX >= 0) {
 				if (isNearEqual(coords.y, lastY+texelY, cursorSize*texelY) && isNearEqual(coords.x, lastX+texelX, cursorSize*texelX/2)) {
@@ -200,7 +202,7 @@ void main()
 		// special handling for "Goto Coords" mode. the effect we want is for
 		// the selected coords to be obvious immediately. we don't want to see
 		// any screen drawing but we do want the alpha fade.
-		if (DrawMode == 2) {
+		if (DrawMode == LateCursor) {
 			if (coords.y > lastY+texelY || (isNearEqual(coords.y, lastY+texelY, texelY) && coords.x > lastX+texelX)) {
 				Out_Color = Frag_Color * texture(Texture, Frag_UV.st);
 				Out_Color.a = 0.5;
@@ -217,7 +219,7 @@ void main()
 	Out_Color = Frag_Color * texture(Texture, Frag_UV.st);
 
 	// if pixel-perfect	rendering is selected then there's nothing much more to do
-	if (CRT == 0 && ImageType != 4) {
+	if (CRT == 0 && ImageType != PrefsCRT) {
 		return;
 	}
 

gui/crt/shaders/generator/generate.go

@@ -19,6 +19,9 @@ package main
 
 import (
 	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
 	"io/ioutil"
 	"os"
 	"strings"
@@ -44,7 +47,7 @@ func read(filename string) (string, error) {
 	return string(s), nil
 }
 
-func generate() (rb bool) {
+func generate(constants constants) (rb bool) {
 	// open file
 	vs, err := read(vertexShader)
 	if err != nil {
@@ -76,7 +79,7 @@ func generate() (rb bool) {
 	output.WriteString("// Code generated by hardware/gui/sdlimgui/shaders/generate.go DO NOT EDIT\n")
 	output.WriteString("\npackage shaders\n\n")
 	output.WriteString(fmt.Sprintf("const Vertex = %s + `\n%s`\n\n", glslVersion, vs))
-	output.WriteString(fmt.Sprintf("const Fragment = %s + `\n%s`\n", glslVersion, fs))
+	output.WriteString(fmt.Sprintf("const Fragment = %s + `\n%s\n%s`\n", glslVersion, constants.String(), fs))
 
 	_, err = f.WriteString(output.String())
 	if err != nil {
@@ -89,8 +92,48 @@ func generate() (rb bool) {
 	return true
 }
 
+type constants map[string]int
+
+func (c *constants) String() string {
+	s := strings.Builder{}
+	for k, v := range *c {
+		s.WriteString(fmt.Sprintf("const int %s = %d;\n", k, v))
+	}
+	return s.String()
+}
+
+func getConstants() (constants, error) {
+	fset := token.NewFileSet()
+	p, err := parser.ParseFile(fset, "../constants.go", nil, 0)
+	if err != nil {
+		fmt.Printf("finding constants: %s\n", err)
+		return nil, err
+	}
+
+	m := make(constants)
+
+	ast.Inspect(p, func(n ast.Node) bool {
+		switch n := n.(type) {
+		case *ast.Ident:
+			if n.IsExported() {
+				if n.Obj.Kind == ast.Con {
+					m[n.Obj.Name] = n.Obj.Data.(int)
+				}
+			}
+		}
+		return true
+	})
+
+	return m, nil
+}
+
 func main() {
-	if !generate() {
+	constants, err := getConstants()
+	if err != nil {
+		os.Exit(10)
+	}
+
+	if !generate(constants) {
 		os.Exit(10)
 	}
 }

gui/crt/shaders/shaders.go

@@ -257,19 +257,19 @@ func (rnd *glsl) render(displaySize [2]float32, framebufferSize [2]float32, draw
 	// set DrawMode according to emulation state
 	switch rnd.img.state {
 	case gui.StatePaused:
-		gl.Uniform1i(rnd.attribDrawMode, 1)
+		gl.Uniform1i(rnd.attribDrawMode, shaders.Cursor)
 	case gui.StateRunning:
 		// if FPS is low enough then show screen draw even though
 		// emulation is running
 		if rnd.img.lz.TV.ReqFPS < 3.0 {
-			gl.Uniform1i(rnd.attribDrawMode, 1)
+			gl.Uniform1i(rnd.attribDrawMode, shaders.NoCursor)
 		} else {
-			gl.Uniform1i(rnd.attribDrawMode, 0)
+			gl.Uniform1i(rnd.attribDrawMode, shaders.Cursor)
 		}
 	case gui.StateRewinding:
-		gl.Uniform1i(rnd.attribDrawMode, 0)
+		gl.Uniform1i(rnd.attribDrawMode, shaders.NoCursor)
 	case gui.StateGotoCoords:
-		gl.Uniform1i(rnd.attribDrawMode, 2)
+		gl.Uniform1i(rnd.attribDrawMode, shaders.LateCursor)
 	}
 
 	if rnd.img.wm.dbgScr.cropped {
@@ -305,15 +305,15 @@ func (rnd *glsl) render(displaySize [2]float32, framebufferSize [2]float32, draw
 				textureID := uint32(cmd.TextureID())
 				switch textureID {
 				case rnd.img.wm.dbgScr.screenTexture:
-					gl.Uniform1i(rnd.attribImageType, 1)
+					gl.Uniform1i(rnd.attribImageType, shaders.DebugScr)
 				case rnd.img.wm.dbgScr.overlayTexture:
-					gl.Uniform1i(rnd.attribImageType, 2)
+					gl.Uniform1i(rnd.attribImageType, shaders.Overlay)
 				case rnd.img.wm.playScr.screenTexture:
-					gl.Uniform1i(rnd.attribImageType, 3)
+					gl.Uniform1i(rnd.attribImageType, shaders.PlayScr)
 				case rnd.img.wm.crtPrefs.crtTexture:
-					gl.Uniform1i(rnd.attribImageType, 4)
+					gl.Uniform1i(rnd.attribImageType, shaders.PrefsCRT)
 				default:
-					gl.Uniform1i(rnd.attribImageType, 0)
+					gl.Uniform1i(rnd.attribImageType, shaders.GUI)
 				}
 
 				// clipping