Hi! I've been writing a vertex and a pixel shader for normal mapping which uses the phong lighting model. I have some serious banding problems as shown in the following screenshot http://users.du.se/~d98ped/banding.jpg
The screenshot is showing the colormap in the lower left corner and the normal map to the right of the colormap.
The shaders seem to work perfectly in RenderMonkey, but
when I use them in the game engine, the banding artifacts appear.
FYI the game engine is RenderWare Graphics 3.7 and the underlying 3D API is DirectX 9.
Does anyone have any clue as to what can cause this problem?
Vertex shader:
float4x4 view_proj_matrix;
float4x4 inv_view_matrix;
float bumpiness;
float4 light_position;
float4 eye_position;
struct VS_INPUT_STRUCT
{
float4 position: POSITION;
float3 normal: NORMAL;
float2 texcoord0: TEXCOORD0;
float3 binormal: BINORMAL0;
float3 tangent: TANGENT0;
};
struct VS_OUTPUT_STRUCT
{
float4 position: POSITION;
float2 bump_map: TEXCOORD0;
float3 light_vector: TEXCOORD1;
float3 half_angle: TEXCOORD2;
};
VS_OUTPUT_STRUCT main( VS_INPUT_STRUCT input )
{
VS_OUTPUT_STRUCT output;
output.position = mul(view_proj_matrix, input.position);
output.bump_map = input.texcoord0;
// Converts from object space to tangent space
float3x3 matObjToTangent = {input.tangent * bumpiness, input.binormal * bumpiness, input.normal};
// light vector from world space -> object space -> tangent space
float3 temp_light_position = mul(inv_view_matrix, light_position);
float3 temp_light_vector2 = normalize(temp_light_position - input.position);
output.light_vector = mul(matObjToTangent, temp_light_vector2);
// view vector from world space -> object space -> tangent space
float3 temp_eye_position = mul(inv_view_matrix, eye_position);
float3 temp_view_vector2 = normalize(temp_eye_position - input.position);
float3 temp_view_vector = mul(matObjToTangent, temp_view_vector2);
output.half_angle = normalize(temp_view_vector + output.light_vector);
return output;
}
Pixel Shader:
//
// Light constants
//
float4 light_color;
float light_intensity;
//
// Material constants
//
float4 specular;
float4 ambient;
float4 diffuse;
float specular_power;
//
// Textures
//
sampler2D base_map;
sampler2D bump_map;
struct PS_INPUT_STRUCT
{
float2 bump_map: TEXCOORD0;
float3 light_vector: TEXCOORD1;
float3 half_angle: TEXCOORD2;
};
// Blinn/Phong lighting model
float4 Phong(float2 dots : POSITION) : COLOR
{
float NdotL = dots.x;
float NdotH = dots.y;
float diffuse_reflection = max(NdotL, 0.0);
float specular_reflection = pow(NdotH, specular_power);
if (NdotL <= 0)
specular_reflection = 0;
return float4(diffuse_reflection, diffuse_reflection, diffuse_reflection, specular_reflection);
}
float4 main( PS_INPUT_STRUCT input ) : COLOR
{
float4 colorMap = tex2D(base_map, input.bump_map);
float3 N = tex2D(bump_map, input.bump_map) * 2.0 - 1.0;
float NdotL = dot(N, input.light_vector);
float NdotH = dot(N, input.half_angle);
float4 light = Phong(float2(NdotL, NdotH)) * light_intensity;
return ambient * colorMap + light * diffuse * colorMap + light.a * specular;
