Reputation: 5880
I need to scale an object in OpenGL|ES 2.0. Shaders:
private final String vertexShaderCode =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"void main() {" +
//the matrix must be included as a modifier of gl_Position
" gl_Position = vPosition * uMVPMatrix;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
Projection:
Matrix.orthoM(mProjMatrix,0,
-1.0f, // Left
1.0f, // Right
-1.0f / ratio, // Bottom
1.0f / ratio, // Top
0.01f, // Near
10000.0f);
Drawing setup:
// Set the camera position (View matrix)
Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
// Calculate the projection and view transformation
Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mVMatrix, 0);
Actual render:
float[] scale = {5f,5f,1f};
Matrix.scaleM(scale_matrix, 0, scale[0], scale[1], scale[2]);
Matrix.multiplyMM(r_matrix, 0, scale_matrix, 0, mMVPMatrix, 0);
// Combine the rotation matrix with the projection and camera view
// Apply the projection and view transformation
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, r_matrix, 0);
And it will not scale. I can see the triangle and I can rotate it. But scaling does not work.
Upvotes: 1
Views: 3489
Reputation: 169
Since vectors are column vectors in OpenGL you have to change the order of the matrix multiplication in your vertex shader:
gl_Position = uMVPMatrix*vPosition;
Upvotes: 4