Translation Matrix skews Model

[Troncoso]

Hello! I've created a cube that sits in space, and a camera to navigate around it:



That works all well and good. My issue comes from trying to translate it. This is the result, of translating by a vector (0, -4, 0):



This is a view from the bottom of the cube looking up. I can scale it and rotate it just fine using the exact same methods I'm using to translate (except using scalar and rotation matrices), so I don't think it's the way I'm applying the transformation. At the same time, my translation matrix is correct as well. Here's how I build the asset:

Building the asset...

public void buildObjects()
	{
		asset = new GLModelAsset();
		
		asset.shaders = new GLProgram(SH_PATH + "vert_shader.vp", SH_PATH + "fragment_shader.fp");
		asset.texture = GLTextureLoader.get().loadTexture("hazard", IMG_PATH + "wooden-crate.jpg");
		
		// Create the VAO
		asset.vao = glGenVertexArrays();
		glBindVertexArray(asset.vao);

		// Create VBO
		asset.vbo = glGenBuffers();
		glBindBuffer(GL_ARRAY_BUFFER, asset.vbo);

		// Build cube array
		float[] verts = {
			     //  X     Y     Z       U     V
			    // bottom
			    -1.0f,-1.0f,-1.0f,   0.0f, 0.0f,
			     1.0f,-1.0f,-1.0f,   1.0f, 0.0f,
			    -1.0f,-1.0f, 1.0f,   0.0f, 1.0f,
			     1.0f,-1.0f,-1.0f,   1.0f, 0.0f,
			     1.0f,-1.0f, 1.0f,   1.0f, 1.0f,
			    -1.0f,-1.0f, 1.0f,   0.0f, 1.0f,

			    // top
			    -1.0f, 1.0f,-1.0f,   0.0f, 0.0f,
			    -1.0f, 1.0f, 1.0f,   0.0f, 1.0f,
			     1.0f, 1.0f,-1.0f,   1.0f, 0.0f,
			     1.0f, 1.0f,-1.0f,   1.0f, 0.0f,
			    -1.0f, 1.0f, 1.0f,   0.0f, 1.0f,
			     1.0f, 1.0f, 1.0f,   1.0f, 1.0f,

			    // front
			    -1.0f,-1.0f, 1.0f,   1.0f, 0.0f,
			     1.0f,-1.0f, 1.0f,   0.0f, 0.0f,
			    -1.0f, 1.0f, 1.0f,   1.0f, 1.0f,
			     1.0f,-1.0f, 1.0f,   0.0f, 0.0f,
			     1.0f, 1.0f, 1.0f,   0.0f, 1.0f,
			    -1.0f, 1.0f, 1.0f,   1.0f, 1.0f,

			    // back
			    -1.0f,-1.0f,-1.0f,   0.0f, 0.0f,
			    -1.0f, 1.0f,-1.0f,   0.0f, 1.0f,
			     1.0f,-1.0f,-1.0f,   1.0f, 0.0f,
			     1.0f,-1.0f,-1.0f,   1.0f, 0.0f,
			    -1.0f, 1.0f,-1.0f,   0.0f, 1.0f,
			     1.0f, 1.0f,-1.0f,   1.0f, 1.0f,

			    // left
			    -1.0f,-1.0f, 1.0f,   0.0f, 1.0f,
			    -1.0f, 1.0f,-1.0f,   1.0f, 0.0f,
			    -1.0f,-1.0f,-1.0f,   0.0f, 0.0f,
			    -1.0f,-1.0f, 1.0f,   0.0f, 1.0f,
			    -1.0f, 1.0f, 1.0f,   1.0f, 1.0f,
			    -1.0f, 1.0f,-1.0f,   1.0f, 0.0f,

			    // right
			     1.0f,-1.0f, 1.0f,   1.0f, 1.0f,
			     1.0f,-1.0f,-1.0f,   1.0f, 0.0f,
			     1.0f, 1.0f,-1.0f,   0.0f, 0.0f,
			     1.0f,-1.0f, 1.0f,   1.0f, 1.0f,
			     1.0f, 1.0f,-1.0f,   0.0f, 0.0f,
			     1.0f, 1.0f, 1.0f,   0.0f, 1.0f
					    };

		FloatBuffer vertsbuffer = BufferUtils.createFloatBuffer(verts.length);
		vertsbuffer.put(verts).flip();

		// Pass the array to the vbo
		glBufferData(GL_ARRAY_BUFFER, vertsbuffer, GL_STATIC_DRAW);

		int floatsize = 4;
		
		// Enable the 'vert' variable in the vertex shader
		glEnableVertexAttribArray(asset.shaders.getAttrib("vert"));
		glVertexAttribPointer(asset.shaders.getAttrib("vert"), 3, GL_FLOAT, false, 5 * floatsize, 0);
		
		
		glEnableVertexAttribArray(asset.shaders.getAttrib("vertTexCoord"));
		glVertexAttribPointer(asset.shaders.getAttrib("vertTexCoord"), 2, GL_FLOAT, true, 5 * floatsize, 3 * floatsize);

		glBindVertexArray(0);
	}

Creating an instance of it...

GLModelInstance i = new GLModelInstance();
i.asset = asset;
i.transform = Matrix4f.translationMatrix(0, -4f, 0);

Drawing it... (its in a for loop because there will be several)

for (GLModelInstance m : objs) {
			GLModelAsset a = m.asset;
			GLProgram program = a.shaders;
			// Get ready to use shader program and vao
			program.use();

			program.setUniformMatrix4("camera", camera.matrix());
			program.setUniformMatrix4("model", m.transform);

			glActiveTexture(GL_TEXTURE0);
			a.texture.bind();
			program.setUniform("tex", 0);

			glBindVertexArray(a.vao);

			// Draw the triangle
			glDrawArrays(GL_TRIANGLES, 0, 36);

			// Release the program and vao
			glBindVertexArray(0);
			a.texture.unbind();
			program.release();
		}

My vertex shader...

# version 330

uniform mat4 camera;
uniform mat4 model;

in vec3 vert;
in vec2 vertTexCoord;

out vec2 fragTexCoord;

void main()
{
	fragTexCoord = vertTexCoord;
	gl_Position = 	camera * model * vec4(vert, 1);
}

And finally, the method that builds a new translation matrix: (The constructor for Matrix4f initializes the matrix to an identity matrix)

public static Matrix4f translationMatrix(float x, float y, float z)
	{
		Matrix4f dest = new Matrix4f();
		
		dest.m03 = x;
		dest.m13 = y;
		dest.m23 = z;
		
		return dest;
	}

I tried messing around with it. Attempting to translate it in different directions only cause it to skew in different directions. Any help would be great.

[Troncoso]

Nevermind...I guess there really was more to the translation matrix than that.

[broumbroum]

I think the Mx be a something more accurate like :

Matrix4f dest = new Matrix4f();
		
		dest.m00 = x;
		dest.m11 = y;
		dest.m22 = z;
                dest.m03 = 1;
                dest.m13 = 1;
                dest.m23 = 1;
		
		return dest;

AFAIK you better try glTranslatef() for yourself.