Shader Demo: Support both GL 3 and 4

7 files changed, 52 insertions, 21 deletions

diff --git a/README.md b/README.md
index 2193a1b..e8794bc 100644
--- a/README.md
+++ b/README.md
@@ -92,9 +92,9 @@ demonstrations:
 
  * `pugl_window_demo` demonstrates multiple top-level windows.
 
- * `pugl_gl3_demo` demonstrates using more modern OpenGL where dynamic loading
-   and shaders are required.  It can also be used to test performance by
-   passing the number of rectangles to draw on the command line.
+ * `pugl_shader_demo` demonstrates using more modern OpenGL (version 3 or 4)
+   where dynamic loading and shaders are required.  It can also be used to test
+   performance by passing the number of rectangles to draw on the command line.
 
  * `pugl_cairo_demo` demonstrates using Cairo on top of the native windowing
    system (without OpenGL), and partial redrawing.
diff --git a/examples/pugl_gl3_demo.c b/examples/pugl_shader_demo.c
index 7b2a49f..ac5fe84 100644
--- a/examples/pugl_gl3_demo.c
+++ b/examples/pugl_shader_demo.c
@@ -15,7 +15,7 @@
 */
 
 /**
-   @file pugl_gl3_demo.c An example of drawing with OpenGL 3.
+   @file pugl_shader_demo.c An example of drawing with OpenGL 3/4.
 
    This is an example of using OpenGL for pixel-perfect 2D drawing.  It uses
    pixel coordinates for positions and sizes so that things work roughly like a
@@ -71,6 +71,8 @@ typedef struct
 	GLuint          instanceVbo;
 	GLuint          ibo;
 	unsigned        framesDrawn;
+	int             glMajorVersion;
+	int             glMinorVersion;
 	int             quit;
 } PuglTestApp;
 
@@ -204,6 +206,8 @@ loadShader(const char* const path)
 static int
 parseOptions(PuglTestApp* app, int argc, char** argv)
 {
+	char* endptr = NULL;
+
 	// Parse command line options
 	app->numRects = 1024;
 	app->opts     = puglParseTestOptions(&argc, &argv);
@@ -212,11 +216,24 @@ parseOptions(PuglTestApp* app, int argc, char** argv)
 	}
 
 	// Parse number of rectangles argument, if given
-	if (argc == 1) {
-		char* endptr = NULL;
-
+	if (argc >= 1) {
 		app->numRects = (size_t)strtol(argv[0], &endptr, 10);
 		if (endptr != argv[0] + strlen(argv[0])) {
+			logError("Invalid number of rectangles: %s\n", argv[0]);
+			return 1;
+		}
+	}
+
+	// Parse OpenGL major version argument, if given
+	if (argc >= 2) {
+		app->glMajorVersion = (int)strtol(argv[1], &endptr, 10);
+		if (endptr != argv[1] + strlen(argv[1])) {
+			logError("Invalid GL major version: %s\n", argv[1]);
+			return 1;
+		} else if (app->glMajorVersion == 4) {
+			app->glMinorVersion = 2;
+		} else if (app->glMajorVersion != 3) {
+			logError("Unsupported GL major version %d\n", app->glMajorVersion);
 			return 1;
 		}
 	}
@@ -241,8 +258,8 @@ setupPugl(PuglTestApp* app, const PuglRect frame)
 	puglSetBackend(app->view, puglGlBackend());
 	puglSetViewHint(app->view, PUGL_USE_COMPAT_PROFILE, PUGL_FALSE);
 	puglSetViewHint(app->view, PUGL_USE_DEBUG_CONTEXT, app->opts.errorChecking);
-	puglSetViewHint(app->view, PUGL_CONTEXT_VERSION_MAJOR, 3);
-	puglSetViewHint(app->view, PUGL_CONTEXT_VERSION_MINOR, 3);
+	puglSetViewHint(app->view, PUGL_CONTEXT_VERSION_MAJOR, app->glMajorVersion);
+	puglSetViewHint(app->view, PUGL_CONTEXT_VERSION_MINOR, app->glMinorVersion);
 	puglSetViewHint(app->view, PUGL_RESIZABLE, app->opts.resizable);
 	puglSetViewHint(app->view, PUGL_SAMPLES, app->opts.samples);
 	puglSetViewHint(app->view, PUGL_DOUBLE_BUFFER, app->opts.doubleBuffer);
@@ -261,8 +278,12 @@ setupGl(PuglTestApp* app)
 		return PUGL_FAILURE;
 	}
 
+	const char* const headerFile = (app->glMajorVersion == 3
+	                                ? "shaders/header_330.glsl"
+	                                : "shaders/header_420.glsl");
+
 	// Load shader sources
-	char* const headerSource   = loadShader("shaders/header_330.glsl");
+	char* const headerSource   = loadShader(headerFile);
 	char* const vertexSource   = loadShader("shaders/rect.vert");
 	char* const fragmentSource = loadShader("shaders/rect.frag");
 	if (!vertexSource || !fragmentSource) {
@@ -362,14 +383,16 @@ teardownGl(PuglTestApp* app)
 int
 main(int argc, char** argv)
 {
-	PuglTestApp app;
-	memset(&app, 0, sizeof(app));
+	PuglTestApp app = {0};
+
+	app.glMajorVersion = 3;
+	app.glMinorVersion = 3;
 
 	const PuglRect frame = {0, 0, defaultWidth, defaultHeight};
 
 	// Parse command line options
 	if (parseOptions(&app, argc, argv)) {
-		puglPrintTestUsage("pugl_gl3_demo", "[NUM_RECTS]");
+		puglPrintTestUsage("pugl_shader_demo", "[NUM_RECTS] [GL_MAJOR]");
 		return 1;
 	}
 
diff --git a/shaders/header_330.glsl b/shaders/header_330.glsl
index 1bcdf05..bfe7a00 100644
--- a/shaders/header_330.glsl
+++ b/shaders/header_330.glsl
@@ -1,3 +1,5 @@
 #version 330 core
 
+#define INTER(qualifiers)
 #define UBO(qualifiers) layout(std140)
+
diff --git a/shaders/header_420.glsl b/shaders/header_420.glsl
new file mode 100644
index 0000000..55fbe8a
--- /dev/null
+++ b/shaders/header_420.glsl
@@ -0,0 +1,5 @@
+#version 420 core
+
+#define INTER(qualifiers) layout(qualifiers)
+#define UBO(qualifiers) layout(std140, qualifiers)
+
diff --git a/shaders/rect.frag b/shaders/rect.frag
index 8622782..ecec50d 100644
--- a/shaders/rect.frag
+++ b/shaders/rect.frag
@@ -8,9 +8,9 @@
    specified precisely in pixels to draw sharp lines.  The border width is just
    hardcoded, but could be made a uniform or vertex attribute easily enough. */
 
-noperspective in vec2 f_uv;
-noperspective in vec2 f_size;
-noperspective in vec4 f_fillColor;
+INTER(location = 0) noperspective in vec2 f_uv;
+INTER(location = 1) noperspective in vec2 f_size;
+INTER(location = 2) noperspective in vec4 f_fillColor;
 
 layout(location = 0) out vec4 FragColor;
 
diff --git a/shaders/rect.vert b/shaders/rect.vert
index ef8c8cc..09f1917 100644
--- a/shaders/rect.vert
+++ b/shaders/rect.vert
@@ -11,9 +11,9 @@ layout(location = 1) in vec2 v_origin;
 layout(location = 2) in vec2 v_size;
 layout(location = 3) in vec4 v_fillColor;
 
-noperspective out vec2 f_uv;
-noperspective out vec2 f_size;
-noperspective out vec4 f_fillColor;
+INTER(location = 0) noperspective out vec2 f_uv;
+INTER(location = 1) noperspective out vec2 f_size;
+INTER(location = 2) noperspective out vec4 f_fillColor;
 
 void
 main()
diff --git a/wscript b/wscript
index 18728df..60fad1d 100644
--- a/wscript
+++ b/wscript
@@ -353,8 +353,9 @@ def build(bld):
             build_example('pugl_print_events',
                           ['examples/pugl_print_events.c'],
                           platform, 'stub')
-            build_example('pugl_gl3_demo',
-                          ['examples/pugl_gl3_demo.c', 'examples/glad/glad.c'],
+            build_example('pugl_shader_demo',
+                          ['examples/pugl_shader_demo.c',
+                           'examples/glad/glad.c'],
                           platform, 'gl', uselib=['DL', 'GL', 'M'])
 
         if bld.env.HAVE_CAIRO: