render: Add shader compatibility for GLSL 3.3.

Big thanks to Aleix Conchillo Flaqué <aconchillo@gmail.com> for
working out the necessary changes while testing Chickadee on MacOS.

6 files changed, 131 insertions, 38 deletions

diff --git a/chickadee/render/particles.scm b/chickadee/render/particles.scm
index d8778da..d046caf 100644
--- a/chickadee/render/particles.scm
+++ b/chickadee/render/particles.scm
@@ -116,13 +116,18 @@ indefinitely."
 (define (make-particles-shader)
   (strings->shader
    "
-#version 130
-
+#ifdef GLSL330
+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
 in vec2 position;
 in vec2 tex;
 in vec2 offset;
 in float life;
-out vec2 frag_tex;
+#endif
+out vec2 fragTex;
 out float t;
 uniform mat4 mvp;
 uniform int lifetime;
@@ -137,21 +142,26 @@ void main(void) {
     float ty = float(tile / animationColumns) / animationRows;
     float tw = 1.0 / animationColumns;
     float th = 1.0 / animationRows;
-    frag_tex = vec2(tx, ty) + tex * vec2(tw, th);
+    fragTex = vec2(tx, ty) + tex * vec2(tw, th);
     gl_Position = mvp * vec4(position.xy + offset, 0.0, 1.0);
 }
 "
    "
-#version 130
-
-in vec2 frag_tex;
+in vec2 fragTex;
 in float t;
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
 uniform sampler2D color_texture;
 uniform vec4 startColor;
 uniform vec4 endColor;
 
 void main (void) {
-    gl_FragColor = mix(endColor, startColor, t) * texture2D(color_texture, frag_tex);
+#ifdef GLSL330
+    fragColor = mix(endColor, startColor, t) * texture(color_texture, fragTex);
+#elif ifdef GLSL130
+    gl_FragColor = mix(endColor, startColor, t) * texture2D(color_texture, fragTex);
+#endif
 }
 "))
 
diff --git a/chickadee/render/pbr.scm b/chickadee/render/pbr.scm
index 2738b77..ab02659 100644
--- a/chickadee/render/pbr.scm
+++ b/chickadee/render/pbr.scm
@@ -91,10 +91,13 @@
   (delay
     (strings->shader
      "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec3 position;
+layout (location = 1) in vec2 texcoord0;
+#elif ifdef GLSL130
 in vec3 position;
 in vec2 texcoord0;
+#endif
 out vec2 fragTex;
 uniform mat4 model;
 uniform mat4 view;
@@ -106,15 +109,19 @@ void main(void) {
 }
 "
      "
-#version 130
-
 in vec2 fragTex;
+out vec4 fragColor;
 uniform vec3 baseColorFactor;
 uniform sampler2D baseColorTexture;
 
 void main (void) {
+#ifdef GLSL330
+  fragColor = texture(baseColorTexture, fragTex) *
+    vec4(baseColorFactor, 1.0);
+#elif ifdef GLSL130
   gl_FragColor = texture2D(baseColorTexture, fragTex) *
     vec4(baseColorFactor, 1.0);
+#endif
 }
 ")))
 
diff --git a/chickadee/render/phong.scm b/chickadee/render/phong.scm
index 0f2a938..08bd7c7 100644
--- a/chickadee/render/phong.scm
+++ b/chickadee/render/phong.scm
@@ -114,11 +114,15 @@
   (delay
     (strings->shader
      "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec3 position;
+layout (location = 1) in vec2 texcoord;
+layout (location = 2) in vec3 normal;
+#elif ifdef GLSL130
 in vec3 position;
 in vec2 texcoord;
 in vec3 normal;
+#endif
 
 uniform mat4 model;
 uniform mat4 view;
@@ -135,8 +139,6 @@ void main() {
 }
 "
      "
-#version 130
-
 struct Material {
   vec3 ambient;
   sampler2D ambientMap;
@@ -162,6 +164,10 @@ struct DirectionalLight {
 in vec3 fragNorm;
 in vec2 fragTex;
 
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
+
 uniform Material material;
 uniform DirectionalLight directionalLight;
 
@@ -170,20 +176,32 @@ void main() {
     vec3 baseDiffuseColor;
     vec3 baseSpecularColor;
     if(material.useAmbientMap) {
+#ifdef GLSL330
+        baseAmbientColor = texture(material.ambientMap, fragTex).xyz;
+#elif ifdef GLSL130
          baseAmbientColor = texture2D(material.ambientMap, fragTex).xyz;
+#endif
     } else {
          baseAmbientColor = vec3(1.0, 1.0, 1.0);
     }
     if(material.useDiffuseMap) {
          // discard transparent fragments.
+#ifdef GLSL330
+         vec4 color = texture(material.diffuseMap, fragTex);
+#elif ifdef GLSL130
          vec4 color = texture2D(material.diffuseMap, fragTex);
+#endif
          if(color.a == 0.0) { discard; }
          baseDiffuseColor = color.xyz;
     } else {
          baseDiffuseColor = vec3(1.0, 1.0, 1.0);
     }
     if(material.useSpecularMap) {
+#ifdef GLSL330
+         baseSpecularColor = texture(material.specularMap, fragTex).xyz;
+#elif ifdef GLSL130
          baseSpecularColor = texture2D(material.specularMap, fragTex).xyz;
+#endif
     } else {
          baseSpecularColor = vec3(1.0, 1.0, 1.0);
     }
@@ -197,7 +215,11 @@ void main() {
         specularFactor = pow(max(dot(lightDir, reflectDir), 0.0), material.shininess);
     }
     vec3 specularColor = specularFactor * baseSpecularColor * material.specular;
+#ifdef GLSL330
+    fragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+#elif ifdef GLSL130
     gl_FragColor = vec4(ambientColor + diffuseColor + specularColor, 1.0);
+#endif
 }
 ")))
 
diff --git a/chickadee/render/shader.scm b/chickadee/render/shader.scm
index baf0302..d393ef0 100644
--- a/chickadee/render/shader.scm
+++ b/chickadee/render/shader.scm
@@ -505,9 +505,27 @@ them into a GPU shader program."
     (info-log gl-get-shaderiv gl-get-shader-info-log id))
   (define (linking-error id)
     (info-log gl-get-programiv gl-get-program-info-log id))
+  (define (glsl-preprocessor-source)
+    ;; Set up preprocessor directives dynamically based on the current
+    ;; OpenGL context's GLSL version so that we can write shaders that
+    ;; are compatible with as many systems as possible.
+    (let ((glsl-version (gpu-glsl-version (current-gpu))))
+      (cond
+       ((string>= glsl-version "3.3")
+        "#version 330
+#define GLSL330
+")
+       ((string>= glsl-version "1.3")
+        "#version 130
+#define GLSL130
+")
+       (else
+        (error "incompatible GLSL version" glsl-version)))))
   (define (make-shader-stage type port)
     (let ((id (gl-create-shader type))
-          (source (get-bytevector-all port)))
+          (source (string->utf8
+                   (string-append (glsl-preprocessor-source)
+                                  (get-string-all port)))))
       (gl-shader-source id 1
                         (bytevector->pointer
                          (u64vector
diff --git a/chickadee/render/shapes.scm b/chickadee/render/shapes.scm
index f7412e8..245bc51 100644
--- a/chickadee/render/shapes.scm
+++ b/chickadee/render/shapes.scm
@@ -58,9 +58,11 @@
            (delay
              (strings->shader
               "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec2 position;
+#elif GLSL130
 in vec2 position;
+#endif
 uniform mat4 mvp;
 
 void main(void) {
@@ -68,13 +70,17 @@ void main(void) {
 }
 "
               "
-#version 130
-
-in vec2 frag_tex;
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
 uniform vec4 color;
 
 void main (void) {
+#ifdef GLSL330
+    fragColor = color;
+#elif ifdef GLSL130
     gl_FragColor = color;
+#endif
 }
 ")))
          (mvp (make-null-matrix4)))
@@ -133,22 +139,26 @@ void main (void) {
            (delay
              (strings->shader
               "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec2 position;
+layout (location = 1) in vec2 tex;
+#elif ifdef GLSL130
 in vec2 position;
 in vec2 tex;
-out vec2 frag_tex;
+#endif
+out vec2 fragTex;
 uniform mat4 mvp;
 
 void main(void) {
-    frag_tex = tex;
+    fragTex = tex;
     gl_Position = mvp * vec4(position.xy, 0.0, 1.0);
 }
 "
               "
-#version 130
-
-in vec2 frag_tex;
+in vec2 fragTex;
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
 uniform vec4 color;
 uniform float r;
 uniform float w;
@@ -159,8 +169,8 @@ float infinity = 1.0 / 0.0;
 
 void main (void) {
   float hw = w / 2.0;
-  float u = frag_tex.x;
-  float v = frag_tex.y;
+  float u = fragTex.x;
+  float v = fragTex.y;
   float dx;
   float dy;
   float d;
@@ -204,9 +214,17 @@ void main (void) {
   }
 
   if (d <= hw) {
+#ifdef GLSL330
+    fragColor = color;
+#elif ifdef GLSL130
     gl_FragColor = color;
+#endif
   } else {
+#ifdef GLSL330
+    fragColor = vec4(color.rgb, color.a * (1.0 - ((d - hw) / r)));
+#elif ifdef GLSL130
     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 b6a8232..c3b7efc 100644
--- a/chickadee/render/sprite.scm
+++ b/chickadee/render/sprite.scm
@@ -49,10 +49,13 @@
   (delay
     (strings->shader
      "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec2 position;
+layout (location = 1) in vec2 tex;
+#elif ifdef GLSL130
 in vec2 position;
 in vec2 tex;
+#endif
 out vec2 fragTex;
 uniform mat4 mvp;
 
@@ -62,14 +65,20 @@ void main(void) {
 }
 "
      "
-#version 130
 
 in vec2 fragTex;
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
 uniform sampler2D colorTexture;
 uniform vec4 tint;
 
 void main (void) {
+#ifdef GLSL330
+    fragColor = texture2D(colorTexture, fragTex) * tint;
+#elif ifdef GLSL130
     gl_FragColor = texture2D(colorTexture, fragTex) * tint;
+#endif
 }
 ")))
 
@@ -380,11 +389,15 @@ may be specified via the TEXTURE-REGION argument."
   (delay
     (strings->shader
      "
-#version 130
-
+#ifdef GLSL330
+layout (location = 0) in vec2 position;
+layout (location = 1) in vec2 tex;
+layout (location = 2) in vec4 tint;
+#elif ifdef GLSL130
 in vec2 position;
 in vec2 tex;
 in vec4 tint;
+#endif
 out vec2 fragTex;
 out vec4 fragTint;
 uniform mat4 mvp;
@@ -396,14 +409,19 @@ void main(void) {
 }
 "
      "
-#version 130
-
 in vec2 fragTex;
 in vec4 fragTint;
+#ifdef GLSL330
+out vec4 fragColor;
+#endif
 uniform sampler2D colorTexture;
 
 void main (void) {
+#ifdef GLSL330
+    fragColor = texture(colorTexture, fragTex) * fragTint;
+#elif ifdef GLSL130
     gl_FragColor = texture2D(colorTexture, fragTex) * fragTint;
+#endif
 }
 ")))