X-Git-Url: https://git.ralfj.de/gltest.git/blobdiff_plain/520f5e8cbcbbe69da6fa878fac2200f7bf302d68..ce1b46da645fdcac80fc9c71082bb5cb40166576:/glutil_gl2.cpp?ds=sidebyside

diff --git a/glutil_gl2.cpp b/glutil_gl2.cpp
index e8cc190..666ede9 100644
--- a/glutil_gl2.cpp
+++ b/glutil_gl2.cpp
@@ -34,6 +34,7 @@ typedef void (*GLATTACHSHADERPROC) (GLuint program, GLuint shader);
 typedef void (*GLLINKPROGRAMPROC) (GLuint program);
 typedef GLint (*GLGETATTRIBLOCATIONPROC) (GLuint program, const GLchar *name);
 typedef void (*GLUSEPROGRAMPROC) (GLuint program);
+
 typedef void (*GLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
 typedef void (*GLENABLEVERTEXATTRIBARRAYPROC) (GLuint index);
 typedef void (*GLGENBUFFERSPROC) (GLsizei n, GLuint *buffers);
@@ -41,6 +42,13 @@ typedef void (*GLBINDBUFFERPROC) (GLenum target, GLuint buffer);
 typedef void (*GLBUFFERDATAPROC) (GLenum target, GLsizeiptr size, const GLvoid *data, GLenum usage);
 typedef void (*GLDELETEBUFFERSPROC) (GLsizei n, const GLuint *buffers);
 
+#ifdef CON_GL3
+// VAOs are only supported in GL3+, and not needed in earler contexts
+typedef void (*GLBINDVERTEXARRAYPROC) (GLuint array);
+typedef void (*GLDELETEVERTEXARRAYSPROC) (GLsizei n, const GLuint *arrays);
+typedef void (*GLGENVERTEXARRAYSPROC) (GLsizei n, GLuint *arrays);
+#endif
+
 GLGETSHADERIVPROC p_glGetShaderiv = NULL;
 GLGETSHADERINFOLOGPROC p_glGetShaderInfoLog = NULL;
 GLCREATESHADERPROC p_glCreateShader = NULL;
@@ -51,6 +59,7 @@ GLATTACHSHADERPROC p_glAttachShader = NULL;
 GLLINKPROGRAMPROC p_glLinkProgram = NULL;
 GLGETATTRIBLOCATIONPROC p_glGetAttribLocation = NULL;
 GLUSEPROGRAMPROC p_glUseProgram = NULL;
+
 GLVERTEXATTRIBPOINTERPROC p_glVertexAttribPointer = NULL;
 GLENABLEVERTEXATTRIBARRAYPROC p_glEnableVertexAttribArray = NULL;
 GLGENBUFFERSPROC p_glGenBuffers = NULL;
@@ -58,6 +67,12 @@ GLBINDBUFFERPROC p_glBindBuffer = NULL;
 GLBUFFERDATAPROC p_glBufferData = NULL;
 GLDELETEBUFFERSPROC p_glDeleteBuffers = NULL;
 
+#ifdef CON_GL3
+GLBINDVERTEXARRAYPROC p_glBindVertexArray = NULL;
+GLDELETEVERTEXARRAYSPROC p_glDeleteVertexArrays = NULL;
+GLGENVERTEXARRAYSPROC p_glGenVertexArrays = NULL;
+#endif
+
 // resolve function pointers
 static T_proc resolveFunctionPointer(T_glGetProcAddress p_glGetProcAddress, const char *name)
 {
@@ -96,6 +111,13 @@ void resolveFunctionPointers(T_glGetProcAddress p_glGetProcAddress)
 	p_glAttachShader = (GLATTACHSHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glAttachShader");
 	p_glLinkProgram = (GLLINKPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glLinkProgram");
 	p_glGetAttribLocation = (GLGETATTRIBLOCATIONPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetAttribLocation");
+
+#ifdef CON_GL3
+	p_glBindVertexArray = (GLBINDVERTEXARRAYPROC)resolveFunctionPointer(p_glGetProcAddress, "glBindVertexArray");
+	p_glDeleteVertexArrays = (GLDELETEVERTEXARRAYSPROC)resolveFunctionPointer(p_glGetProcAddress, "glDeleteVertexArrays");
+	p_glGenVertexArrays = (GLGENVERTEXARRAYSPROC)resolveFunctionPointer(p_glGetProcAddress, "glGenVertexArrays");
+#endif
+
 	p_glUseProgram = (GLUSEPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glUseProgram");
 	p_glVertexAttribPointer = (GLVERTEXATTRIBPOINTERPROC)resolveFunctionPointer(p_glGetProcAddress, "glVertexAttribPointer");
 	p_glEnableVertexAttribArray = (GLENABLEVERTEXATTRIBARRAYPROC)resolveFunctionPointer(p_glGetProcAddress, "glEnableVertexAttribArray");
@@ -105,6 +127,32 @@ void resolveFunctionPointers(T_glGetProcAddress p_glGetProcAddress)
 	p_glDeleteBuffers = (GLDELETEBUFFERSPROC)resolveFunctionPointer(p_glGetProcAddress, "glDeleteBuffers");
 }
 
+static const char *glErrorToString(GLenum e)
+{
+#define CASE(name) case name: return #name
+	switch (e) {
+		CASE(GL_NO_ERROR);
+		CASE(GL_INVALID_ENUM);
+		CASE(GL_INVALID_VALUE);
+		CASE(GL_INVALID_OPERATION);
+#ifndef CON_GLES2
+		CASE(GL_STACK_OVERFLOW);
+		CASE(GL_STACK_UNDERFLOW);
+#endif
+		CASE(GL_OUT_OF_MEMORY);
+		default: return "<unknown>";
+	}
+#undef CASE
+}
+
+static void checkGlError(const char *what)
+{
+	GLenum e = glGetError();
+	if (e == GL_NO_ERROR) return;
+	fprintf(stderr, "GL error %d (%s): %s\n", e, glErrorToString(e), what);
+	exit(1);
+}
+
 // shaders
 static const char *vertex_shader_source =
 "#version 100 \n\
@@ -155,6 +203,7 @@ static GLuint compile_shader(GLenum shader_type, const char *source)
 		show_info_log(shader);
 		exit(1);
 	}
+	checkGlError("Compiling shader");
 	return shader;
 }
 
@@ -164,6 +213,7 @@ static GLuint createArrayBuffer(GLsizeiptr size, GLfloat *data)
 	p_glGenBuffers(1, &buffer);
 	p_glBindBuffer(GL_ARRAY_BUFFER, buffer);
 	p_glBufferData(GL_ARRAY_BUFFER, size, data, GL_STATIC_DRAW);
+	checkGlError("Creating array buffer");
 	return buffer;
 }
 
@@ -184,6 +234,15 @@ void initialise2dProjection()
 void drawQuad(GLfloat red, GLfloat green, GLfloat blue, GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2)
 {
 	p_glUseProgram(program);
+	checkGlError("Enabling the shaders");
+
+#ifdef CON_GL3
+	// create a vertex array obect and use it
+	GLuint vao;
+	p_glGenVertexArrays(1, &vao);
+	p_glBindVertexArray(vao);
+	checkGlError("Creating a VAO");
+#endif
 	
 	// send vertex data to card with given attribute
 	GLfloat vertex_buffer_data[] = {
@@ -201,7 +260,9 @@ void drawQuad(GLfloat red, GLfloat green, GLfloat blue, GLfloat x1, GLfloat y1,
 		0,                                /* stride */
 		(void*)0                          /* array buffer offset */
 	);
+	checkGlError("Preparing vertex data");
 	p_glEnableVertexAttribArray(attributes.position);
+	checkGlError("Sending vertex data");
 	
 	// same with color data
 	GLfloat color_buffer_data[] = {
@@ -219,12 +280,19 @@ void drawQuad(GLfloat red, GLfloat green, GLfloat blue, GLfloat x1, GLfloat y1,
 		0,                             /* stride */
 		(void*)0                       /* array buffer offset */
 	);
+	checkGlError("Preparing color data");
 	p_glEnableVertexAttribArray(attributes.color);
+	checkGlError("Sending color data");
 	
 	// draw
 	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+	checkGlError("Drawing");
 	
 	// cleanup
 	p_glDeleteBuffers(1, &vertex_buffer);
 	p_glDeleteBuffers(1, &color_buffer);
+#ifdef CON_GL3
+	p_glDeleteVertexArrays(1, &vao);
+#endif
+	checkGlError("Doing cleanup");
 }