diff --git a/J/shader.h b/J/shader.h
index 423e2b0..78eee00 100644
--- a/J/shader.h
+++ b/J/shader.h
@@ -13,6 +13,7 @@
 #include <fstream>
 #include <stdexcept>
 #include <map>
+#include <vector>
 #include <iterator>
 
 #import "basic.h"
@@ -21,28 +22,25 @@
 // TODO: add error checking at set_uniforms?
 // TODO: use an uniform map? (benchmark first!)
 // TODO: allow arrays is uniforms (now all counts are 1)
+// TODO: matrix attributes are not handled well (they take up 4 indices in the attributes)
 
 namespace J {
-    
-enum {
-    ATTRIB_VERTEX,
-    ATTRIB_COLOR,
-    NUM_ATTRIBUTES
-};
 
 class shader {
-    // NOTE: it could be hardcoded to use vertex_shader and fragment_shader.
-    typedef std::map<GLenum, GLuint> ShaderMap;
+    // NOTE: it could be hardcoded to use vertex_shader and fragment_shader, for ShaderMap.
+    typedef std::map<GLenum, GLuint> ShaderMap;             // shader_type -> shader_name
+    typedef std::map<std::string, GLuint> AttributeMap;     // attribute_name -> attribute_index
     
 	GLuint program;
 	ShaderMap shaders;
+    AttributeMap attributes;
 
 public:
 
     // ***********
     // constructor
-	shader(std::string vertex_shader_filename, std::string fragment_shader_filename) :
-	program(0), shaders() {
+	shader(const std::string& vertex_shader_filename, const std::string& fragment_shader_filename, const std::vector<std::string>& attributes_to_use = std::vector<std::string>()) :
+	program(0), shaders(), attributes() {
 		program = glCreateProgram();
 		if(program == 0) {
 			throw std::runtime_error("Program couldn't be created");
@@ -61,11 +59,9 @@ public:
 				throw std::runtime_error(fragment_shader_filename + " couldn't be opened");
 			compile_shader(fragment_shader, GL_FRAGMENT_SHADER);
 		}
-        {   // TODO: think of a nice way to implement this
-            // Bind attribute locations.
-            // This needs to be done prior to linking.
-            glBindAttribLocation(program, ATTRIB_VERTEX, "position");
-            glBindAttribLocation(program, ATTRIB_COLOR, "color");
+        for (unsigned int i = 0; i < attributes_to_use.size(); ++i) {
+            glBindAttribLocation(program, i, attributes_to_use[i].c_str());
+            attributes[attributes_to_use[i]] = i;
         }
 
 		link_program();
@@ -95,6 +91,14 @@ public:
 	void end() {
 		glUseProgram(0);
 	}
+    
+    // *****************
+    // attribute setters
+    void set_attribute(const std::string& name, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid* ptr){
+        const GLuint index = attributes[name];
+        glVertexAttribPointer(index, size, type, normalized, stride, ptr);
+        glEnableVertexAttribArray(index);
+    }
 
     // ***************
     // uniform setters
@@ -168,15 +172,15 @@ public:
 	}
 
     // matrices (in ES2 only square matrices)
-	void set_uniform(char const* name, const GLfloat (&value)[16], GLboolean trans = GL_FALSE) const {
+	void set_uniform(char const* name, const GLfloat (&value)[16], GLboolean trans) const {
 		glUniformMatrix4fv(glGetUniformLocation(program, name), 1, trans, value);
 	}
     
-    void set_uniform(char const* name, const GLfloat (&value)[9], GLboolean trans = GL_FALSE) const {
+    void set_uniform(char const* name, const GLfloat (&value)[9], GLboolean trans) const {
 		glUniformMatrix3fv(glGetUniformLocation(program, name), 1, trans, value);
 	}
     
-    void set_uniform(char const* name, const GLfloat (&value)[4], GLboolean trans = GL_FALSE) const {
+    void set_uniform(char const* name, const GLfloat (&value)[4], GLboolean trans) const {
 		glUniformMatrix2fv(glGetUniformLocation(program, name), 1, trans, value);
 	}
 
@@ -198,7 +202,7 @@ public:
         glGetProgramiv(program, GL_VALIDATE_STATUS, &status);
         if(status == GL_FALSE){
             std::cerr << "validator reports:" << std::endl;
-            show_log();
+            show_program_log();
 			throw std::runtime_error("Program not valid");
         }
         #endif
@@ -248,7 +252,7 @@ private:
 		if(status == GL_FALSE || shader == 0) {
 			std::cerr << "source:\n" << source << std::endl;
 			std::cerr << "shader reports:" << std::endl;
-            show_log();
+            show_shader_log(shader);
 			throw std::runtime_error("Shader failed to compile");
 		}
         #endif
@@ -260,17 +264,26 @@ private:
 		glGetProgramiv(program, GL_LINK_STATUS, &status);
 		if(status == GL_FALSE) {
             std::cerr << "linker reports:" << std::endl;
-            show_log();
+            show_program_log();
 			throw std::runtime_error("Shader failed to link");
 		}
         #endif
     }
     
-    void show_log(std::ostream& out = std::cerr) {
-        GLsizei infoLength = 0;
+    void show_program_log(std::ostream& out = std::cerr) {
+        GLint infoLength = 0;
         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLength);
-        char* infoBuffer = new GLchar[infoLength];
-        glGetProgramInfoLog(program, infoLength, &infoLength, infoBuffer);
+        char* infoBuffer = new GLchar[infoLength+10];
+        glGetProgramInfoLog(program, infoLength+10, &infoLength, infoBuffer);
+        out << infoBuffer << std::endl;
+        delete [] infoBuffer;
+    }
+    
+    void show_shader_log(GLuint shader, std::ostream& out = std::cerr) {
+        GLint infoLength = 0;
+        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLength);
+        char* infoBuffer = new GLchar[infoLength+10];
+        glGetShaderInfoLog(shader, infoLength+10, &infoLength, infoBuffer);
         out << infoBuffer << std::endl;
         delete [] infoBuffer;
     }