Open GLES Normal Map Shader Lighting Incorrect

Question

I tried to create an Open GL ES normal map shader. The mesh I used works fine in Blender, but my shader doesnt. I tried to use the mesh in another Sample Program, too. It seems like it does only work on some faces. Is this a shader problem or a mesh/tangent problem?

enter image description here

VP

uniform mat4 worldViewProjMatrix;
uniform mat4 worldViewMatrix;

attribute vec4 vertex;
attribute vec3 normal;
attribute vec3 tangent;
attribute vec3 binormal;
attribute vec4 uv0;

varying vec3 v_Position;
varying vec3 v_Normal;
varying vec3 v_Tangent;
varying vec3 v_Binormal;
varying vec2 v_UV;

void main()
{
    v_Position = (vec4(vertex.xyz, 1.0) * worldViewMatrix).xyz;
    v_Normal = ((worldViewMatrix * vec4(normalize(normal), 0.0)).xyz);
    v_Tangent = ((worldViewMatrix * vec4(normalize(tangent), 0.0)).xyz);
    v_Binormal = ((worldViewMatrix * vec4(normalize(binormal), 0.0)).xyz);//normalize(cross(v_Normal, v_Tangent));
    v_UV = uv0.st;

    gl_Position = worldViewProjMatrix * vec4(vertex.xyz, 1.0);
}

FP

uniform vec4 lightPositionViewSpace;
uniform vec4 surfaceDiffuseColour;
uniform vec4 surfaceAmbientColour;
uniform sampler2D tex0;

varying vec3 v_Position;
varying vec3 v_Normal;
varying vec3 v_Tangent;
varying vec3 v_Binormal;
varying vec2 v_UV;

void main()
{
    mat3 TBN = transpose(mat3(
        v_Tangent,
        v_Binormal,
        v_Normal
    ));

    vec3 lightVector = normalize(lightPositionViewSpace.xyz);//normalize(lightPositionViewSpace.xyz - v_Position);
    lightVector = normalize(lightVector*TBN);

    vec3 normal = normalize(texture2D(tex0, v_UV).rgb*2.0 - 1.0);

    float diffuse = max(dot(normal, lightVector), 0.0);

    gl_FragColor = surfaceDiffuseColour*diffuse+surfaceAmbientColour;
}

look here: [Normal mapping gone horribly wrong](http://stackoverflow.com/a/28541305/2521214) for some hints — Spektre, Jul 25 '15 at 07:17
My bet is your light vectors are not correctly set/computed/transformed, and also the final color combination is suspicious. I usually transform the normal vector by the TBN not the light vector ...Without more info about your uniforms and coordinate systems is hard to answer ... — Spektre, Jul 25 '15 at 07:23

score 1 · Accepted Answer · answered Jul 25 '15 at 19:22

I dont know whats wrong with the above code. But I wrote a new one, which seems to work. Maybe this is gonna help someone who wants a simple Open GLES Normal Map Shader:

VP

uniform mat4 worldViewProjMatrix;
uniform vec4 lightDirObjSpace;

attribute vec4 vertex;
attribute vec3 normal;
attribute vec3 tangent;
attribute vec3 binormal;
attribute vec4 uv0;

varying vec2 vTexCoord;
varying vec3 vLightVector;

void main( void )
{
   vTexCoord = uv0.st;

   vLightVector.x = dot( lightDirObjSpace.xyz, tangent );
   vLightVector.y = dot( lightDirObjSpace.xyz, binormal );
   vLightVector.z = dot( lightDirObjSpace.xyz, normal );

   gl_Position = worldViewProjMatrix * vec4(vertex.xyz, 1.0);
}

FP

uniform vec3 surfaceDiffuseColour;
uniform vec3 surfaceAmbientColour;
uniform sampler2D tex0;

varying vec2 vTexCoord;
varying vec3 vLightVector;

void main(void)
{
   vec3 normal = normalize(((texture2D( tex0, vTexCoord ).xyz) * 2.0) - 1.0);

   float diffuse = max(0.0, dot(normalize(normal), normalize(vLightVector)));

   gl_FragColor = vec4(surfaceDiffuseColour * diffuse + surfaceAmbientColour, 1.0);
}

Open GLES Normal Map Shader Lighting Incorrect

1 Answers1