I am new in shader concepts and I am trying to implement a sprite of 8x8 in OpenGL ES.
I want to move the texture in the vertex shader but I cant figure out how to this, my code may be wrong, feel free to correct me
If I change this line in the vertex shader, the texture scale but I want to move not scale!:
v_TexCoordinate = a_TexCoordinate*vec2(1.5,1.5);
Vertex shader:
uniform mat4 u_MVPMatrix; // A constant representing the combined model/view/projection matrix.
uniform mat4 u_MVMatrix; // A constant representing the combined model/view matrix.
uniform mat4 u_TextureMatrix;
attribute vec4 a_Position; // Per-vertex position information we will pass in.
attribute vec3 a_Normal; // Per-vertex normal information we will pass in.
attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in.
varying vec3 v_Position; // This will be passed into the fragment shader.
varying vec3 v_Normal; // This will be passed into the fragment shader.
varying vec2 v_TexCoordinate; // This will be passed into the fragment shader.
// The entry point for our vertex shader.
void main()
{
// Transform the vertex into eye space.
v_Position = vec3(u_MVMatrix * a_Position);
// Pass through the texture coordinate.
v_TexCoordinate = a_TexCoordinate;
// Transform the normal's orientation into eye space.
v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0));
// gl_Position is a special variable used to store the final position.
// Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
gl_Position = u_MVPMatrix * a_Position;
}
This is my draw fuction
private void drawMagia()
{
GLES20.glUseProgram(mMagiaProgramHandle);
mTextureMatrixHandle = GLES20.glGetUniformLocation(mMagiaProgramHandle, "u_TextureMatrix");
mMagiaTextureCoordinateHandle = GLES20.glGetAttribLocation(mMagiaProgramHandle, "a_TexCoordinate");
mMagiaPositions.position(0);
GLES20.glVertexAttribPointer(mPositionHandle, mPositionDataSize, GLES20.GL_FLOAT, false,
0, mMagiaPositions);
GLES20.glEnableVertexAttribArray(mPositionHandle);
// Pass in the normal information
mMagiaNormals.position(0);
GLES20.glVertexAttribPointer(mNormalHandle, mNormalDataSize, GLES20.GL_FLOAT, false,
0, mMagiaNormals);
GLES20.glEnableVertexAttribArray(mNormalHandle);
// Pass in the texture coordinate information
mMagiaTextureCoordinates.position(0);
GLES20.glVertexAttribPointer(mTextureCoordinateHandle, mTextureCoordinateDataSize, GLES20.GL_FLOAT, false,
0, mMagiaTextureCoordinates);
GLES20.glEnableVertexAttribArray(mTextureCoordinateHandle);
// This multiplies the view matrix by the model matrix, and stores the
// result in the MVP matrix
// (which currently contains model * view).
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
// Pass in the modelview matrix.
GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(mTextureMatrixHandle, 1, false, mTextureMatrix, 0);
// This multiplies the modelview matrix by the projection matrix, and
// stores the result in the MVP matrix
// (which now contains model * view * projection).
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
// Pass in the combined matrix.
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
// Pass in the light position in eye space.
GLES20.glUniform3f(mLightPosHandle, mLightPosInEyeSpace[0], mLightPosInEyeSpace[1], mLightPosInEyeSpace[2]);
// Draw the square.
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 6);
}
