Instancing code doesn't work

Hey guys,

For the last couple of days I got interested in Instanced Rendering. After some research and examples, I tried to do a little test myself.
I followed this guide: http://programming4.us/multimedia/8306.aspx , but I’m using LWJGL, so I ported it to Java:

shader.vert:

precision highp float;

in vec4 position;
in vec4 instance_color;
in vec4 instance_position;

out Fragment
{
    vec4 color;
} fragment;

uniform mat4 mvp;

void main(void)
{
    gl_Position = mvp * (position + instance_position);
    fragment.color = instance_color;
}

Code itself:


int shaderProgram = glCreateProgram();
		int vertexShader = glCreateShader(GL_VERTEX_SHADER);
		
		StringBuilder vertexShaderSource = new StringBuilder();
		BufferedReader reader = null;
		
		try {
            reader = new BufferedReader(new FileReader("src/shader.vert"));
            String line;
            while ((line = reader.readLine()) != null) {
                vertexShaderSource.append(line).append('
');
            }
        } catch (IOException e) {
            System.err.println("Vertex shader wasn't loaded properly.");
            e.printStackTrace();
            Display.destroy();
            System.exit(1);
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
                }
            }
        }
		
		glShaderSource(vertexShader, vertexShaderSource);
		glCompileShader(vertexShader);
		if (glGetShader(vertexShader, GL_COMPILE_STATUS) == GL_FALSE) {
            System.err.println("Vertex shader wasn't able to be compiled correctly.");
        }
		
		glAttachShader(shaderProgram, vertexShader);
		glBindAttribLocation(shaderProgram, 0, "position");
		glBindAttribLocation(shaderProgram, 1, "instance_color");
        glBindAttribLocation(shaderProgram, 2, "instance_position");
        
        glLinkProgram(shaderProgram);
		
		int vaid;
		int bid;
		IntBuffer va = BufferUtils.createIntBuffer(1);
		IntBuffer b = BufferUtils.createIntBuffer(1);
		glGenVertexArrays(va);
		glGenBuffers(b);
		bid = b.get(0);
		vaid = va.get(0);
		
		glBindVertexArray(vaid);
		glBindBuffer(GL_ARRAY_BUFFER, bid);
		
		int offset = 0;
		
		 FloatBuffer square_vertices_fb = BufferUtils.createFloatBuffer(square_vertices.length);
		 square_vertices_fb.put(square_vertices);
		 square_vertices_fb.rewind();
		 
		 FloatBuffer instance_colors_fb = BufferUtils.createFloatBuffer(instance_colors.length);
		 instance_colors_fb.put(instance_colors);
		 instance_colors_fb.rewind();
		 
		 FloatBuffer instance_positions_fb = BufferUtils.createFloatBuffer(instance_positions.length);
		 instance_positions_fb.put(instance_positions);
		 instance_positions_fb.rewind();
		
		glBufferData(GL_ARRAY_BUFFER, square_vertices.length + instance_colors.length + instance_positions.length, GL_STATIC_DRAW);
		
		glBufferSubData(GL_ARRAY_BUFFER, 0, square_vertices_fb);
		glBufferSubData(GL_ARRAY_BUFFER, square_vertices.length, instance_colors_fb);
		glBufferSubData(GL_ARRAY_BUFFER, square_vertices.length + instance_colors.length, instance_positions_fb);
		
		glVertexAttribPointer(0, 4, GL_FLOAT, false, 0, 0);
		glVertexAttribPointer(1, 4, GL_FLOAT, false, 0, square_vertices.length);
		glVertexAttribPointer(2, 4, GL_FLOAT, false, 0, square_vertices.length + instance_colors.length);
		
		glEnableVertexAttribArray(0);
		glEnableVertexAttribArray(1);
		glEnableVertexAttribArray(2);
		
		glVertexAttribDivisor(1, 1);
		glVertexAttribDivisor(2, 1);
        
        
		while (!Display.isCloseRequested()) {
			try {
				
				glClear(GL_COLOR_BUFFER_BIT);
				
				glBegin(GL_LINES);
				glColor3f(1, 0, 0);
				glVertex3f(-50, -2, -20);
				glVertex3f(50, -2, -20);

				glColor3f(0, 1, 0);
				glVertex3f(0, -50, -20);
				glVertex3f(0, 50, -20);

				glColor3f(0, 0, 1);
				glVertex3f(0, -2, -100);
				glVertex3f(0, -2, 10);
				glEnd();
				
				glUseProgram(shaderProgram);
				
				glBindVertexArray(vaid);
				GL31.glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, 4);
				
			    glUseProgram(0);
				Display.update();
			} catch (Exception e) {
				e.printStackTrace();
				System.exit(1);
			}
		}

I get no error messages.

The axis drawing works fine, but I get no squares in my view! Any ideas on what’s wrong? It has been driving me crazy for a few days now!

Thanks for the help!

~Basaa

Hello,

you need a vertex and a fragment shader in your shader program, I only see a vertex shader.

Thank you for the answer. As I’m completely new to shaders, and the example didn’t provide a fragment shader, could you give me a basic fragment shader?

Thanks, I appreciate it!

Edit:
I tried this, without any success:


void main(void)
{
	gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
}

Can you render anything without instancing with your shaders? How did you set up the shaders? Have you checked for shader compile errors, shader linker errors and OpenGL errors (glGetError) ?

Compiling works fine the status said it’s compiled successfully. I dont know how to check if there are link errors. Could you provide me with an example?

Thanks again for your help :slight_smile:

Edit:
I tried to get the error code, and I get a 1281 code just after the first glBufferSubData. Any ideas why?’

Edit 2:
Error is fixed, seems that LWJGL wants the offset in bytes, so *4.

However, now I get no error anywhere, but I don’t see anything on my screen.
Any ideas?

[QUOTE=Basaaa;1246000]Compiling works fine the status said it’s compiled successfully. I dont know how to check if there are link errors. Could you provide me with an example?
[/QUOTE]

See the example code here: http://www.opengl.org/wiki/OpenGL_Shading_Language#Error_Checking

Thanks for the answer, but I already fixed the error.
I placed it in my last posts. I now simply don’t get anything on my screen.

Thanks!

And I have still open questions: Are there any linking errors (shader linker, not c++ linker)? You asked to to query those, that’s why i provided the link with code. Second question is how your code looks like now (as you have added a fragment shader and other fixes).

Hi guys,

I still have not found the solution, and I really want this to work. I packed the eclipse project in a rar. Could anyone please take a look at the code, and see if anything is wrong?

Click

If you want to help me, you can also add me on Skype: Masterleik.

Thanks for your time, I really do appreciate it!

~Basaa