Pixel Processing for the Terrain Effect in Font

Generating PDF 417 in Font Pixel Processing for the Terrain Effect

All values generated by the vertex shader are interpolated by the rasterizer, a process that can change the length of the vectors passed from the vertex shader to the pixel shader. Therefore, the first thing you need to do in the pixel shader is normalize all the vectors, making sure their length becomes exactly 1.0 again. Remember that this needs to be done to yield correct lighting.

eyeVec = normalize(IN.eyeVec); lightVec1 = normalize(IN.lightVec1); lightVec2 = normalize(IN.lightVec2); halfwayVec1 = normalize(lightVec1 + eyeVec); halfwayVec2 = normalize(lightVec2 + eyeVec); normal = normalize(IN.normal);

At this point, you have all the vectors necessary for the lighting calculation. You ll do the lighting calculation using the Phong equation, which is implemented in the phongShading method. This method takes into account the light color, the halfway vector, and the angle between the normal and the light direction. As a result, it returns how much the object should be lit in the diffuseColor output and how much more shiny the object should be in the specularColor output. Put this method immediately after your vertex shader: void phongShading(in float3 normal, in float3 lightVec, in float3 halfwayVec, in float3 lightColor, out float3 diffuseColor, out float3 specularColor) { float diffuseInt = saturate(dot(normal, lightVec)); diffuseColor = diffuseInt * lightColor; float specularInt = saturate(dot(normal, halfwayVec)); specularInt = pow(specularInt, specularPower); specularColor = specularInt * lightColor; } Use the method in your pixel shader to calculate the diffuse and specular lighting contributions of both lights in your scene: // Calculate diffuse and specular color for each light float3 diffuseColor1, diffuseColor2; float3 specularColor1, specularColor2; phongShading(normal, lightVec1, halfwayVec1, light1Color, diffuseColor1, specularColor1); phongShading(normal, lightVec2, halfwayVec2, light2Color , diffuseColor2, specularColor2); Now you know how much the pixel should be lit, but you still need to know the color of the pixel. You calculate this color by sampling and combining the four diffuse textures that are applied to the terrain according to the values in the alpha map texture. Each component of the alpha map stores a value used to linearly interpolate between the colors of the diffuse textures: float3 float3 float3 float3 float4 color1 = tex2D(diffuseSampler1, IN.uv1 2.xy); color2 = tex2D(diffuseSampler2, IN.uv1 2.zw); color3 = tex2D(diffuseSampler3, IN.uv3 4.xy); color4 = tex2D(diffuseSampler4, IN.uv3 4.zw); alpha = tex2D(alphaSampler, IN.uv5 6.zw);

// Combine using the alpha map float3 combinedColor = lerp(color1, color2, alpha.x); combinedColor = lerp(combinedColor , color3, alpha.y); combinedColor = lerp(combinedColor , color4, alpha.z);

Finally, you combine the lighting conditions with the base color of the pixel by multiplying them: float4 finalColor; finalColor.a = 1.0f; finalColor.rgb = combinedColor * ( (diffuseColor1 + diffuseColor2) * materialDiffuseColor + ambientLightColor) + (specularColor1 + specularColor2) * materialSpecularColor; The complete pixel shader code follows: float4 TerrainPS(v2f IN) : COLOR0 { float3 eyeVec = normalize(IN.eyeVec); float3 lightVec1 = normalize(IN.lightVec1); float3 lightVec2 = normalize(IN.lightVec2); float3 halfwayVec1 = normalize(lightVec1 + eyeVec); float3 halfwayVec2 = normalize(lightVec2 + eyeVec); float3 normal = normalize(IN.normal); float3 float3 float3 float3 float4 color1 = tex2D(diffuseSampler1, IN.uv1 2.xy); color2 = tex2D(diffuseSampler2, IN.uv1 2.zw); color3 = tex2D(diffuseSampler3, IN.uv3 4.xy); color4 = tex2D(diffuseSampler4, IN.uv3 4.zw); alpha = tex2D(alphaSampler, IN.uv5 6.xy);

float3 combinedColor = lerp(color1, color2, alpha.x); combinedColor = lerp(combinedColor , color3, alpha.y); combinedColor = lerp(combinedColor , color4, alpha.z); // Calculate diffuse and specular color for each light float3 diffuseColor1, diffuseColor2; float3 specularColor1, specularColor2; phongShading(normal, lightVec1, halfwayVec1, light1Color, diffuseColor1, specularColor1); phongShading(normal, lightVec2, halfwayVec2, light2Color, diffuseColor2, specularColor2); // Phong lighting result float4 finalColor; finalColor.a = 1.0f; finalColor.rgb = combinedColor * ( (diffuseColor1 + diffuseColor2) * diffuseColor + ambientLightColor) + (specularColor1 + specularColor2) * specularColor; return finalColor; }

To finish your effect, you need to define a technique that combines the vertex shader and pixel shader you just defined. Use this code to finalize your Terrain.fx file: technique TerrainMultiTextured { pass p0 { VertexShader = compile vs 2 0 TerrainVS(); PixelShader = compile ps 2 0 TerrainPS(); } } In the technique definition, you indicate the technique is rendered in a single pass, which vertex and pixel shader to use, and that both your vertex and pixel shaders can be compiled for shader version 2.0.