diff --git a/source/app.d b/source/app.d
index 44ded8d..3fa1d07 100644
--- a/source/app.d
+++ b/source/app.d
@@ -159,8 +159,8 @@ struct PixelBuffer {
 			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
 			//linearly interpolate between pixels, MIN if texture is too small for drawing area, MAG if drawing area is smaller than texture
-			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+			glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
 			//texture type, level, format to store as, width, height, border, format loaded in
 			glTexImage2D(GL_TEXTURE_2D, 0, input_format_, width_, height_, 0, output_format_, data_type_, pixels);
@@ -205,7 +205,7 @@ struct PixelBuffer {
 		void update(void[] pixels, size_t offset = 0) {
 
 			bind(0);
-			glBufferSubData(GL_ARRAY_BUFFER, cast(GLintptr)offset, pixels.length, pixels.ptr);
+			glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width_, height_, input_format_, data_type_, pixels.ptr);
 			unbind();
 
 		} // update
@@ -241,13 +241,14 @@ struct PixelBuffer {
 			glBindBuffer(GL_ARRAY_BUFFER, vbo_);
 			glBufferData(GL_ARRAY_BUFFER, vertices.length * vertices[0].sizeof, vertices.ptr, draw_type);
 
+			// pos
 			glEnableVertexAttribArray(0);
 			glVertexAttribPointer(0,
-				vertices[0].length,
+				2,
 				GL_FLOAT,
 				GL_FALSE,
-				vertices[0].sizeof,
-				vertices.ptr
+				float.sizeof * 2,
+				null
 			);
 
 			glBindVertexArray(0);
@@ -280,13 +281,12 @@ struct PixelBuffer {
 		uniform vec2 screen_size;
 
 		layout(location = 0) in vec2 pos;
-		layout(location = 1) in vec2 uv;
 
 		out vec2 frag_uv;
 
 		void main() {
-			frag_uv = uv;
-			gl_Position = vec4(pos, 0.0, 0.0);
+			gl_Position = vec4(pos, 0.0, 1.0);
+			frag_uv = clamp(pos, vec2(0.0, 0.0), vec2(1.0, 1.0));
 		}
 
 	};
@@ -301,7 +301,9 @@ struct PixelBuffer {
 		out vec4 out_col;
 
 		void main() {
-			out_col = texture(tex, frag_uv.st);
+			float v = texture(tex, frag_uv.st).r;
+			out_col = vec4(v, v, v, 1.0);
+			// out_col = vec4(1.0, 0.0, 0.0, 1.0);
 		}
 
 	};
@@ -313,17 +315,17 @@ struct PixelBuffer {
 	void create(void* pixels, int w, int h) {
 
 		float[2][6] rect = [
-			[0.0f, 0.0f], // top left
-			[1.0f, 0.0f], // top right
+			[-1.0f, -1.0f], // top left
+			[1.0f, -1.0f], // top right
 			[1.0f, 1.0f], // bottom right
 
-			[0.0f, 0.0f], // top left
-			[0.0f, 1.0f], // bottom left
+			[-1.0f, -1.0f], // top left
+			[-1.0f, 1.0f], // bottom left
 			[1.0f, 1.0f], // bottom right
 		];
 
 		vao.create(rect[]);
-		tex.create(pixels, w, h);
+		tex.create(pixels, w, h, GL_RED, GL_RED);
 		shader.compile(&vs_shader, &fs_shader);
 
 	} // create
@@ -338,6 +340,11 @@ struct PixelBuffer {
 		
 	} // draw
 
+	nothrow @nogc
+	void update(void[] pixels, size_t offset = 0) {
+		tex.update(pixels, offset);
+	} // update
+
 } // PixelBuffer
 
 struct Chip8Status {
@@ -637,7 +644,7 @@ struct Chip8 {
 				switch (cpu.opcode & 0x0FFF) {
 
 					case 0x00E0: // 0x00E0 Clears the screen.
-						// screen_buf[0..$] = 0;
+						screen_buf[0..$] = 0;
 						draw_flag = true;
 						break;
 
@@ -1005,11 +1012,14 @@ struct Emulator {
 		// setup debug ui
 		status.initialize(&this, &emu);
 
-		// set up pixel buffer to poke at
-		emu.screen_data[0][] = 255;
-		buf.create(emu.screen_data.ptr, 64, 32);
+		// debug data
+		emu.screen_buf[0] = 255;
+		emu.screen_buf[64 - 1] = 255;
+		emu.screen_buf[64*32 - 64] = 255;
+		emu.screen_buf[64*32 - 1] = 255;
 
-		emu.screen_buf[] = 255;
+		// set up pixel buffer to poke a
+		buf.create(emu.screen_buf.ptr, 64, 32);
 
 	}
 
@@ -1061,6 +1071,10 @@ struct Emulator {
 		int w, h;
 		window.windowSize(w, h);
 
+		if (emu.draw_flag) {
+			buf.update(emu.screen_buf);
+		}
+
 		buf.draw(w, h);
 		imgui.newFrame(window);