From c6ead0aeb6b2ab78d7d77907b2180dea98dcb473 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 24 Aug 2020 21:21:58 -0400
Subject: render: Take a stab at GLSL 1.2 compatibility.

I don't have a machine to test on so this is just a best guess.  I'm
sure there's some bugs that other people will just have to point out
to me.  It's a start, at least.
---
 chickadee/render/particles.scm | 17 ++++++++++++++++-
 chickadee/render/pbr.scm       | 17 +++++++++++++++--
 chickadee/render/phong.scm     | 24 +++++++++++++++++++-----
 chickadee/render/shader.scm    |  4 ++++
 chickadee/render/shapes.scm    | 23 ++++++++++++++++++-----
 chickadee/render/sprite.scm    | 31 ++++++++++++++++++++++++++++---
 6 files changed, 100 insertions(+), 16 deletions(-)

diff --git a/chickadee/render/particles.scm b/chickadee/render/particles.scm
index d046caf..c81209a 100644
--- a/chickadee/render/particles.scm
+++ b/chickadee/render/particles.scm
@@ -121,14 +121,24 @@ layout (location = 0) in vec2 position;
 layout (location = 1) in vec2 tex;
 layout (location = 2) in vec2 offset;
 layout (location = 3) in float life;
-#elif ifdef GLSL130
+#elif defined(GLSL130)
 in vec2 position;
 in vec2 tex;
 in vec2 offset;
 in float life;
+#elif defined(GLSL120)
+attribute vec2 position;
+attribute vec2 tex;
+attribute vec2 offset;
+attribute float life;
 #endif
+#ifdef GLSL120
+varying vec2 fragTex;
+varying float t;
+#else
 out vec2 fragTex;
 out float t;
+#endif
 uniform mat4 mvp;
 uniform int lifetime;
 uniform int animationRows;
@@ -147,8 +157,13 @@ void main(void) {
 }
 "
    "
+#ifdef GLSL120
+attribute vec2 fragTex;
+attribute float t;
+#else
 in vec2 fragTex;
 in float t;
+#endif
 #ifdef GLSL330
 out vec4 fragColor;
 #endif
diff --git a/chickadee/render/pbr.scm b/chickadee/render/pbr.scm
index ab02659..167334e 100644
--- a/chickadee/render/pbr.scm
+++ b/chickadee/render/pbr.scm
@@ -94,11 +94,18 @@
 #ifdef GLSL330
 layout (location = 0) in vec3 position;
 layout (location = 1) in vec2 texcoord0;
-#elif ifdef GLSL130
+#elif defined(GLSL130)
 in vec3 position;
 in vec2 texcoord0;
+#elif defined(GLSL120)
+attribute vec3 position;
+attribute vec2 texcoord0;
 #endif
+#ifdef GLSL120
+varying vec2 fragTex;
+#else
 out vec2 fragTex;
+#endif
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 projection;
@@ -109,8 +116,14 @@ void main(void) {
 }
 "
      "
+#ifdef GLSL120
+attribute vec2 fragTex;
+#else
 in vec2 fragTex;
+#endif
+#ifdef GLSL330
 out vec4 fragColor;
+#endif
 uniform vec3 baseColorFactor;
 uniform sampler2D baseColorTexture;
 
@@ -118,7 +131,7 @@ void main (void) {
 #ifdef GLSL330
   fragColor = texture(baseColorTexture, fragTex) *
     vec4(baseColorFactor, 1.0);
-#elif ifdef GLSL130
+#else
   gl_FragColor = texture2D(baseColorTexture, fragTex) *
     vec4(baseColorFactor, 1.0);
 #endif
diff --git a/chickadee/render/phong.scm b/chickadee/render/phong.scm
index 08bd7c7..1c718a8 100644
--- a/chickadee/render/phong.scm
+++ b/chickadee/render/phong.scm
@@ -118,18 +118,27 @@
 layout (location = 0) in vec3 position;
 layout (location = 1) in vec2 texcoord;
 layout (location = 2) in vec3 normal;
-#elif ifdef GLSL130
+#elif defined(GLSL130)
 in vec3 position;
 in vec2 texcoord;
 in vec3 normal;
+#elif defined(GLSL120)
+attribute vec3 position;
+attribute vec2 texcoord;
+attribute vec3 normal;
 #endif
 
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 projection;
 
+#ifdef GLSL120
+varying vec3 fragNorm;
+varying vec2 fragTex;
+#else
 out vec3 fragNorm;
 out vec2 fragTex;
+#endif
 
 void main() {
     gl_Position = projection * view * model * vec4(position, 1.0);
@@ -161,8 +170,13 @@ struct DirectionalLight {
     vec3 specular;
 };
 
+#ifdef GLSL120
+attribute vec3 fragNorm;
+attribute vec2 fragTex;
+#else
 in vec3 fragNorm;
 in vec2 fragTex;
+#endif
 
 #ifdef GLSL330
 out vec4 fragColor;
@@ -178,7 +192,7 @@ void main() {
     if(material.useAmbientMap) {
 #ifdef GLSL330
         baseAmbientColor = texture(material.ambientMap, fragTex).xyz;
-#elif ifdef GLSL130
+#else
          baseAmbientColor = texture2D(material.ambientMap, fragTex).xyz;
 #endif
     } else {
@@ -188,7 +202,7 @@ void main() {
          // discard transparent fragments.
 #ifdef GLSL330
          vec4 color = texture(material.diffuseMap, fragTex);
-#elif ifdef GLSL130
+#else
          vec4 color = texture2D(material.diffuseMap, fragTex);
 #endif
          if(color.a == 0.0) { discard; }
@@ -199,7 +213,7 @@ void main() {
     if(material.useSpecularMap) {
 #ifdef GLSL330
          baseSpecularColor = texture(material.specularMap, fragTex).xyz;
-#elif ifdef GLSL130
+#else
          baseSpecularColor = texture2D(material.specularMap, fragTex).xyz;
 #endif
     } else {
@@ -217,7 +231,7 @@ void main() {
     vec3 specularColor = specularFactor * baseSpecularColor * material.specular;
 #ifdef GLSL330
     fragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
-#elif ifdef GLSL130
+#else
     gl_FragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
 #endif
 }
diff --git a/chickadee/render/shader.scm b/chickadee/render/shader.scm
index d393ef0..6df77f1 100644
--- a/chickadee/render/shader.scm
+++ b/chickadee/render/shader.scm
@@ -518,6 +518,10 @@ them into a GPU shader program."
        ((string>= glsl-version "1.3")
         "#version 130
 #define GLSL130
+")
+       ((string>= glsl-version "1.2")
+        "#version 120
+#define GLSL120
 ")
        (else
         (error "incompatible GLSL version" glsl-version)))))
diff --git a/chickadee/render/shapes.scm b/chickadee/render/shapes.scm
index 245bc51..dd690ec 100644
--- a/chickadee/render/shapes.scm
+++ b/chickadee/render/shapes.scm
@@ -60,8 +60,10 @@
               "
 #ifdef GLSL330
 layout (location = 0) in vec2 position;
-#elif GLSL130
+#elif defined(GLSL130)
 in vec2 position;
+#elif defined(GLSL120)
+attribute vec2 position;
 #endif
 uniform mat4 mvp;
 
@@ -78,7 +80,7 @@ uniform vec4 color;
 void main (void) {
 #ifdef GLSL330
     fragColor = color;
-#elif ifdef GLSL130
+#else
     gl_FragColor = color;
 #endif
 }
@@ -142,11 +144,18 @@ void main (void) {
 #ifdef GLSL330
 layout (location = 0) in vec2 position;
 layout (location = 1) in vec2 tex;
-#elif ifdef GLSL130
+#elif defined(GLSL130)
 in vec2 position;
 in vec2 tex;
+#elif defined(GLSL120)
+attribute vec2 position;
+attribute vec2 tex;
 #endif
+#ifdef GLSL120
+varying vec2 fragTex;
+#else
 out vec2 fragTex;
+#endif
 uniform mat4 mvp;
 
 void main(void) {
@@ -155,7 +164,11 @@ void main(void) {
 }
 "
               "
+#ifdef GLSL120
+attribute vec2 fragTex;
+#else
 in vec2 fragTex;
+#endif
 #ifdef GLSL330
 out vec4 fragColor;
 #endif
@@ -216,13 +229,13 @@ void main (void) {
   if (d <= hw) {
 #ifdef GLSL330
     fragColor = color;
-#elif ifdef GLSL130
+#else
     gl_FragColor = color;
 #endif
   } else {
 #ifdef GLSL330
     fragColor = vec4(color.rgb, color.a * (1.0 - ((d - hw) / r)));
-#elif ifdef GLSL130
+#else
     gl_FragColor = vec4(color.rgb, color.a * (1.0 - ((d - hw) / r)));
 #endif
   }
diff --git a/chickadee/render/sprite.scm b/chickadee/render/sprite.scm
index 144c656..a5c25bc 100644
--- a/chickadee/render/sprite.scm
+++ b/chickadee/render/sprite.scm
@@ -55,8 +55,15 @@ layout (location = 1) in vec2 tex;
 #elif ifdef GLSL130
 in vec2 position;
 in vec2 tex;
+#elif ifdef GLSL120
+attribute vec2 position;
+attribute vec2 tex;
 #endif
+#ifdef GLSL120
+varying vec2 fragTex;
+#else
 out vec2 fragTex;
+#endif
 uniform mat4 mvp;
 
 void main(void) {
@@ -66,7 +73,11 @@ void main(void) {
 "
      "
 
+#ifdef GLSL120
+attribute vec2 fragTex;
+#else
 in vec2 fragTex;
+#endif
 #ifdef GLSL330
 out vec4 fragColor;
 #endif
@@ -76,7 +87,7 @@ uniform vec4 tint;
 void main (void) {
 #ifdef GLSL330
     fragColor = texture(colorTexture, fragTex) * tint;
-#elif ifdef GLSL130
+#else
     gl_FragColor = texture2D(colorTexture, fragTex) * tint;
 #endif
 }
@@ -393,13 +404,22 @@ may be specified via the TEXTURE-REGION argument."
 layout (location = 0) in vec2 position;
 layout (location = 1) in vec2 tex;
 layout (location = 2) in vec4 tint;
-#elif ifdef GLSL130
+#elif defined(GLSL130)
 in vec2 position;
 in vec2 tex;
 in vec4 tint;
+#elif defined(GLSL120)
+attribute vec2 position;
+attribute vec2 tex;
+attribute vec4 tint;
 #endif
+#ifdef GLSL120
+varying vec2 fragTex;
+varying vec2 fragTint;
+#else
 out vec2 fragTex;
 out vec4 fragTint;
+#endif
 uniform mat4 mvp;
 
 void main(void) {
@@ -409,8 +429,13 @@ void main(void) {
 }
 "
      "
+#ifdef GLSL120
+attribute vec2 fragTex;
+attribute vec4 fragTint;
+#else
 in vec2 fragTex;
 in vec4 fragTint;
+#endif
 #ifdef GLSL330
 out vec4 fragColor;
 #endif
@@ -419,7 +444,7 @@ uniform sampler2D colorTexture;
 void main (void) {
 #ifdef GLSL330
     fragColor = texture(colorTexture, fragTex) * fragTint;
-#elif ifdef GLSL130
+#else
     gl_FragColor = texture2D(colorTexture, fragTex) * fragTint;
 #endif
 }
-- 
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