I wrote a pretty long question here: http://stackoverflow.com/questions/3...ransformations

but I'll also add some of the questions details down below.

I am making some basic steps towards rendering with opengl. I wrote some shaders as well as a some math functions to do the linear algebra.

I can get a quad that's 2d tris to render on screen but when it comes to applying any sort of transformations I see nothing.

Here is the relevant code as to the matrix data that I am sending to the gpu, etc.

**setup matricies**

Code :mat4identity(&vm); vec3f eye = {0, 0, 0}; vec3f center = {0, 0, -1}; vec3f up = {0, 1, 0}; mat4LookAt(&vm, &eye, ¢er, &up); mat4print("lookat",&vm); mat4OrthoProjection(&opm, 200, 0, 200, 0, 0.001, 1000.0); mat4print("2d projection",&opm);

**render code**

Code :glUseProgram(sp); glBindVertexArray(vao1); pMat = getUniformLocation(sp, "proj"); vMat = getUniformLocation(sp, "view"); transMat = getUniformLocation(sp, "transform"); glUniformMatrix4dv(pMat, 1, GL_FALSE, opm.m); glUniformMatrix4dv(vMat, 1, GL_FALSE, vm.m); glUniformMatrix4dv(transMat, 1, GL_FALSE, tm.m); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); glBindVertexArray(0);

the mat4 is a column major struct in c.

**mat4 lookat function**

Code :mat4* lookat(vec3f* eye, vec3f* center, vec3f* up) { vec3f x = {1, 0, 0}; vec3f y = {0, 1, 0}; vec3f z = {0, 0, 1}; z = vec3fsub(eye, center); vec3fnorm(z); x = vec3fcross(y, z); y = vec3fcross(z, x); vec3fnorm(x); vec3fnorm(y); double x1, y1, z1; x1 = vec3fdotr(&x, eye); y1 = vec3fdotr(&y, eye); z1 = vec3fdotr(&z, eye); double data[] = { (&x)->p[0], (&y)->p[0], (&z)->p[0], 0, (&x)->p[1], (&y)->p[1], (&z)->p[1], 0, (&x)->p[2], (&y)->p[2], (&z)->p[2], 0, x1, y1, z1, 1 }; return makeMat4(data); }

**orthographic projection code**

Code :mat4* mat4Projection(double r, double l, double t, double b, double n, double f) { double data[] = { (2*n)/(r-l), 0, (r+l)/(r-l), 0, 0, (2*n)/(t-b), (t+b)/(t-b), 0, 0, 0, (-(f+n))/(f-n), (-2*(f*n))/(f-n), 0, 0, -1, 1 }; return makeMat4(data); }

I also try to send down just a simple transform matrix that moves the objects 20 units in the +z direction. Running the above code and printing out the matrices along the way I get these results.

Code :lookat matrix [ 1.000000 0.000000 0.000000 0.000000 ] [ 0.000000 1.000000 0.000000 0.000000 ] [ 0.000000 0.000000 1.000000 0.000000 ] [ 0.000000 0.000000 0.000000 1.000000 ] 2d projection matrix [ 0.010000 0.000000 0.000000 -1.000000 ] [ 0.000000 0.010000 0.000000 -1.000000 ] [ 0.000000 0.000000 -0.002000 -1.000002 ] [ 0.000000 0.000000 0.000000 1.000000 ] translation matrix [ 1.000000 0.000000 0.000000 0.000000 ] [ 0.000000 1.000000 0.000000 0.000000 ] [ 0.000000 0.000000 1.000000 20.000000 ] [ 0.000000 0.000000 0.000000 1.000000 ]

The error could be at this line when I am sending the data to the gpu

Code :glUniformMatrix4dv(pMat, 1, GL_FALSE, opm.m);

but again I am not sure. This is the vertex shader:

Code :#version 330 core uniform mat4 view; uniform mat4 proj; in vec3 position; void main() { gl_Position = proj * view * vec4(position.x, position.y, position.z, 1.0); }

removing the proj and view transformations I get the rectangle in the middle of the screen. Using either projection or view transformations and I can't see anything on screen, just the clear background.