Hi folks,
I am currently trying to implement some simple diffuse lighting into my game and have come across a odd problem.
The direction of the light produces incorrect results.
Currently I have the following inputs, along with my vertex and pixel shader:
struct VertexShaderInput
{
float4 Position : POSITION0;
float2 TexCoord : TEXCOORD0;
float3 N : NORMAL0;
float4 Color : COLOR0;
};
struct VertexShaderOutput
{
float4 Position : POSITION0;
float2 TexCoord : TEXCOORD0;
float3 L : TEXCOORD1;
float3 N : TEXCOORD2;
float4 Color : COLOR0;
};
struct PixelShaderOutput
{
float4 Color : COLOR0;
};
//=============================================
//------------ Technique: Default -------------
//=============================================
VertexShaderOutput VertexShader(VertexShaderInput input)
{
VertexShaderOutput output;
output.Position = mul(input.Position, xWorldViewProjection);
output.TexCoord = input.TexCoord;
output.Color = input.Color;
// Will be moved into PixelShader for deferred rendering
float3 lightDirection = float3(0.0f, 1.0f, 0.0f);
output.L = normalize(lightDirection); // Light Direction (normalised)
output.N = normalize(mul(input.N, xWorld)); // Surface Normal (normalised) [World Coordinates]
return output;
}
PixelShaderOutput PixelShader(VertexShaderOutput input)
{
PixelShaderOutput output;
// [Ambient Light] I = Ai * Ac
float Ambient_Intensity = 0.1f;
float4 Ambient_Colour = float4(1.0f, 1.0f, 1.0f, 1.0f);
float4 Ambient_Light = Ambient_Intensity * Ambient_Colour;
// [Diffuse Light] I = Di * Dc * N.L
float Diffuse_Intensity = 1.0f;
float4 Diffuse_Colour = float4(0.0f, 0.0f, 1.0f, 1.0f);
float NdotL = dot(input.N, input.L);
float4 Diffuse_Light = Diffuse_Intensity * Diffuse_Colour * saturate(NdotL);
output.Color = (Ambient_Light + Diffuse_Light) * tex2D(TextureSampler0, input.TexCoord);
return output;
}
A light direction of (1, 0, 0) produces the following incorrect result:
however, the opposite direction (-1, 0, 0) produces no result:
The same occurs for (0, 1, 0)
with a negative y direction (0, -1, 0) producing no result:
In all cases the original texture is chequered white/grey and the diffuse light is blue.
Can anyone please tell me what I have done wrong?
Thank you.
