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VodacekWorks

Projective texture and Light Pre-Pass

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Hi, I have almost half of a year problem with implementation projective texture in my Light Pre-Pass renderer. My projector don't affect albedo and is drawn in lighting pass. I have this projector View a Projection matrix:
Matrix projection = Matrix.CreateOrthographicOffCenter(-halfWidth * Scale, halfWidth * Scale, -halfHeight * Scale, halfHeight * Scale, -1000, 1000);
Matrix view = Matrix.CreateLookAt(Position, Target, Vector3.Up);


Where halfWidth and halfHeight is half texture width and height, Position is Projector position and target is projector target. This seems to be ok. I am drawing full screen quad with this shader:
float4x4 InvViewProjection;

texture2D DepthTexture;
texture2D NormalTexture;
texture2D ProjectorTexture;

float4x4 ProjectorViewProjection;

sampler2D depthSampler = sampler_state {
texture = <DepthTexture>;
minfilter = point;
magfilter = point;
mipfilter = point;
};

sampler2D normalSampler = sampler_state {
texture = <NormalTexture>;
minfilter = point;
magfilter = point;
mipfilter = point;
};

sampler2D projectorSampler = sampler_state {
texture = <ProjectorTexture>;
AddressU = Clamp;
AddressV = Clamp;
};

float viewportWidth;
float viewportHeight;

// Calculate the 2D screen position of a 3D position
float2 postProjToScreen(float4 position) {
float2 screenPos = position.xy / position.w;
return 0.5f * (float2(screenPos.x, -screenPos.y) + 1);
}

// Calculate the size of one half of a pixel, to convert
// between texels and pixels
float2 halfPixel() {
return 0.5f / float2(viewportWidth, viewportHeight);
}

struct VertexShaderInput {
float4 Position : POSITION0;
};

struct VertexShaderOutput {
float4 Position :POSITION0;
float4 PositionCopy : TEXCOORD1;
};

VertexShaderOutput VertexShaderFunction(VertexShaderInput input) {
VertexShaderOutput output;
output.Position = input.Position;
output.PositionCopy=output.Position;
return output;
}

float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 {
float2 texCoord =postProjToScreen(input.PositionCopy) + halfPixel();

// Extract the depth for this pixel from the depth map
float4 depth = tex2D(depthSampler, texCoord);
//return float4(depth.r,0,0,1);
// Recreate the position with the UV coordinates and depth value
float4 position;
position.x = texCoord.x * 2 - 1;
position.y = (1 - texCoord.y) * 2 - 1;
position.z = depth.r;
position.w = 1.0f;

// Transform position from screen space to world space
position = mul(position, InvViewProjection);
position.xyz /= position.w;
//compute projection
float3 projection=tex2D(projectorSampler,postProjToScreen(mul(position,ProjectorViewProjection)) + halfPixel());
return float4(projection,1);
}


In first part of pixel shader is recovered position from G-buffer (this code I am using in other shaders without any problem) and then is tranformed to projector viewprojection space. Where is hidden my mistake? Thanks for advice and please be tolerant to my english.

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