From ecc281c56a8c3c297cfd2f0b6d4671b2000efd9b Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 4 Apr 2020 13:36:45 +0200
Subject: Shader Demo: Factor out version-dependent GLSL header

---
 examples/pugl_gl3_demo.c |  4 +++-
 examples/shader_utils.h  | 21 +++++++++++++--------
 2 files changed, 16 insertions(+), 9 deletions(-)

(limited to 'examples')

diff --git a/examples/pugl_gl3_demo.c b/examples/pugl_gl3_demo.c
index f43592d..6f7ed91 100644
--- a/examples/pugl_gl3_demo.c
+++ b/examples/pugl_gl3_demo.c
@@ -259,6 +259,7 @@ setupGl(PuglTestApp* app)
 	}
 
 	// Load shader sources
+	char* const headerSource   = loadShader("shaders/header_330.glsl");
 	char* const vertexSource   = loadShader("shaders/rect.vert");
 	char* const fragmentSource = loadShader("shaders/rect.frag");
 	if (!vertexSource || !fragmentSource) {
@@ -267,9 +268,10 @@ setupGl(PuglTestApp* app)
 	}
 
 	// Compile rectangle shaders and program
-	app->drawRect = compileProgram(vertexSource, fragmentSource);
+	app->drawRect = compileProgram(headerSource, vertexSource, fragmentSource);
 	free(fragmentSource);
 	free(vertexSource);
+	free(headerSource);
 	if (!app->drawRect.program) {
 		return PUGL_FAILURE;
 	}
diff --git a/examples/shader_utils.h b/examples/shader_utils.h
index 834d8fc..2fd26c5 100644
--- a/examples/shader_utils.h
+++ b/examples/shader_utils.h
@@ -28,11 +28,12 @@ typedef struct
 } Program;
 
 static GLuint
-compileShader(const char* source, const GLenum type)
+compileShader(const char* header, const char* source, const GLenum type)
 {
-	GLuint    shader       = glCreateShader(type);
-	const int sourceLength = (int)strlen(source);
-	glShaderSource(shader, 1, &source, &sourceLength);
+	const GLchar* sources[] = {header, source};
+	const GLint   lengths[] = {(GLint)strlen(header), (GLint)strlen(source)};
+	GLuint        shader    = glCreateShader(type);
+	glShaderSource(shader, 2, sources, lengths);
 	glCompileShader(shader);
 
 	int status;
@@ -61,13 +62,17 @@ deleteProgram(Program program)
 }
 
 static Program
-compileProgram(const char* vertexSource, const char* fragmentSource)
+compileProgram(const char* headerSource,
+               const char* vertexSource,
+               const char* fragmentSource)
 {
 	static const Program nullProgram = {0, 0, 0};
 
-	Program program = {compileShader(vertexSource, GL_VERTEX_SHADER),
-	                   compileShader(fragmentSource, GL_FRAGMENT_SHADER),
-	                   glCreateProgram()};
+	Program program = {
+	    compileShader(headerSource, vertexSource, GL_VERTEX_SHADER),
+	    compileShader(headerSource, fragmentSource, GL_FRAGMENT_SHADER),
+	    glCreateProgram(),
+	};
 
 	if (!program.vertexShader || !program.fragmentShader || !program.program) {
 		deleteProgram(program);
-- 
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