Kotlin/Android/OpenGL ES: Cannot implement 3D Lighting using normals. Wanted index: 4294967295. Max index: 16

Question

I'm trying to implement 3d Lighting on a model using OpenGL ES. I followed this guide https://arm-software.github.io/opengl-es-sdk-for-android/lighting.html, but I cannot figure out why I keep getting this error : Info: Invalid vertex attribute index. Wanted index: 4294967295. Max index: 16.

Both coordinates and norms are Float array of size 9 which are later cast to floatBuffers. When I just want to draw shape everything works (therefore vertexBuffer is probably ok), but when I try to use norms everything breaks down.

I would really appreciate any help with this problem.

Buffers creation:

    private var vertexBuffer: FloatBuffer =
        ByteBuffer.allocateDirect(triangleCoordinates.size * 4).run {
            order(ByteOrder.nativeOrder())
            asFloatBuffer().apply {
                put(triangleCoordinates)
                position(0)
            }
        }


    private var normalsBuffer: FloatBuffer =
        ByteBuffer.allocateDirect(normals.size * 4).run {
            order(ByteOrder.nativeOrder())
            asFloatBuffer().apply {
                put(normals)
                position(0)
            }
        }

vertex Shader Code

private val vertexShaderCode =
    "attribute vec4 vertexPosition;\n" +
                "attribute vec3 vertexColour;\n" +
                "attribute vec3 vertexNormal;\n" +
                "varying vec3 fragColour;\n" +
                "uniform mat4 modelView;\n" +
                "void main(){\n" +
                /* [Setup scene vectors.] */
                "    vec3 transformedVertexNormal = normalize((modelView * vec4(vertexNormal, 0.0)).xyz);" +
                "    vec3 inverseLightDirection = normalize(vec3(0.0, 1.0, 1.0));\n" +
                "    fragColour = vec3(0.0);\n" +
                /* [Setup scene vectors.] */
                "\n" +
                /* [Calculate the diffuse component.] */
                "    vec3 diffuseLightIntensity = vec3(1.0, 1.0, 1.0);\n" +
                "    vec3 vertexDiffuseReflectionConstant = vertexColour;\n" +
                "    float normalDotLight = max(0.0, dot(transformedVertexNormal, inverseLightDirection));\n" +
                //"    fragColour += normalDotLight * vertexDiffuseReflectionConstant * diffuseLightIntensity;\n" +

                "    /* Make sure the fragment colour is between 0 and 1. */" +
                "    clamp(fragColour, 0.0, 1.0);\n" +
                "\n" +
                "    gl_Position = modelView * vertexPosition;\n" +
                "}\n";

Drawing code:

fun draw(mvpMatrix: FloatArray) {

        positionHandle = glGetAttribLocation(program, "vertexPosition")
        vertexNormalLocation = glGetAttribLocation(program, "vertexNormal")

        mColorHandle = glGetUniformLocation(program, "vertexColour").also { colorHandle ->
            glUniform4fv(colorHandle, 1, color, 0)
        }

        vPMatrixHandle = glGetUniformLocation(program, "modelView")
        glUniformMatrix4fv(vPMatrixHandle, 1, false, mvpMatrix, 0)

        glUseProgram(program)

        glVertexAttribPointer(
            positionHandle,
            3,
            GLES20.GL_FLOAT,
            false,
            vertexStride,
            vertexBuffer
        )

        glVertexAttribPointer(
            vertexNormalLocation,
            3,
            GL_FLOAT,
            false,
            0,
            normalsBuffer
        )

        glEnableVertexAttribArray(positionHandle)
        glEnableVertexAttribArray(vertexNormalLocation)


        glDrawArrays(GL_TRIANGLES, 0, vertexCount)
        glDisableVertexAttribArray(positionHandle)
    }

Rabbid76 Rabbid76 · Accepted Answer · 2021-09-19T11:36:30

4294967295 is hexadecimal ffffffff respectively -1. This is, because the vertexColour attribute is not an active program resource.
If an attribute is not uses (directly or indirectly) it is optimized out by the compiler or linker and does not get an attribute index.

Kotlin/Android/OpenGL ES: Cannot implement 3D Lighting using normals. Wanted index: 4294967295. Max index: 16

1 Answers