CosmicEngine/assets/shaders/slang/triangle.slang

struct VSInput {
    [[vk::location(0)]] float3 inPosition;
    [[vk::location(1)]] float4 inColor;
    [[vk::location(2)]] float3 inNormal;
    [[vk::location(3)]] float2 inUV;
    [[vk::location(4)]] float3 inTangent;
    [[vk::location(5)]] float3 inBitangent;
};

struct VSOutput
{
    float4 pos : SV_Position;
    float4 color : COLOR;
    float2 uv : TEXCOORD0;
    float3 normal : NORMAL;
    float3 fragPos : TEXCOORD1; // position monde
    float3 viewPos  : TEXCOORD2; // position caméra
};

// set 0 - Camera
struct CameraUBO {
    float4x4 view;
    float4x4 projection;
};
[[vk::binding(0, 0)]] ConstantBuffer<CameraUBO> camera;

// set 1 - Transform
struct TransformUBO {
    float4x4 model;
};
[[vk::binding(0, 1)]] ConstantBuffer<TransformUBO> transform;

// set 2 - Material
[[vk::binding(1, 2)]] Sampler2D albedoTexture;  // texture + sampler combinés, pas de warning
[[vk::binding(2, 2)]] Sampler2D normalTexture;  // deuxième texture si besoin

struct LightData {
    float4 position;  // w = type
    float4 direction; // w = range
    float4 color;     // w = intensity
    float innerCosAngle;
    float outerCosAngle;
    float attenuation;
    float padding;
};

struct LightsBuffer {
    LightData lights[32];
    int lightCount;
};

[[vk::binding(0, 3)]] StructuredBuffer<LightsBuffer> lightsBuffer;

[shader("vertex")]
VSOutput vertMain(VSInput input) {
    VSOutput output;

    float4x4 modelMatrix = transform.model;
    float4 worldPos = mul(modelMatrix, float4(input.inPosition, 1.0));
    output.pos = mul(camera.projection, mul(camera.view, worldPos));
    output.color = input.inColor;
    output.uv = input.inUV;

    // Pour une mise à l'échelle uniforme, on peut utiliser directement la matrice 3x3
    float3x3 normalMatrix = (float3x3)modelMatrix;
    // Si mises à l'échelle non-uniforme :
    // float3x3 normalMatrix = transpose(inverse((float3x3)modelMatrix));

    output.normal = normalize(mul(normalMatrix, input.inNormal));
    output.fragPos = worldPos.xyz;

    // Position de la caméra dans le monde
    float3x3 R = (float3x3)camera.view;
    output.viewPos = -mul(transpose(R), camera.view[3].xyz);

    return output;
}

float3 computeDirectional(LightData light, VSOutput vertIn)
{
    // Normaliser la normale (l'interpolation peut la dénormaliser)
    float3 normal = normalize(vertIn.normal);

    // Direction de la lumière (utiliser les données de la lumière)
    float3 lightDir = normalize(-light.direction.xyz);

    // Direction de la vue
    float3 viewDir = normalize(vertIn.viewPos - vertIn.fragPos);

    // Diffuse (Lambertian)
    float diff = max(dot(normal, lightDir), 0.0);
    float3 diffuse = diff * light.color.xyz * light.color.w;

    // Specular (Blinn-Phong)
    float3 halfVec = normalize(lightDir + viewDir);
    float spec = pow(max(dot(normal, halfVec), 0.0), 32.0);
    float3 specular = spec * light.color.xyz * light.color.w * 0.5;

    // Retourner la somme
    return (diffuse + specular) * light.attenuation;
}

float3 computePoint(LightData light, VSOutput vertIn)
{
    float3 normal = normalize(vertIn.normal);
    float3 viewDir = normalize(vertIn.viewPos - vertIn.fragPos);

    // Direction de la lumière (du point lumineux vers le fragment)
    float3 lightDir = normalize(light.position.xyz - vertIn.fragPos);

    // Distance pour l'atténuation
    float distance = length(light.position.xyz - vertIn.fragPos);
    float attenuation = 1.0 / (1.0 + light.attenuation * distance * distance);

    // Diffuse
    float diff = max(dot(normal, lightDir), 0.0);
    float3 diffuse = diff * light.color.xyz * light.color.w;

    // Specular
    float3 halfVec = normalize(lightDir + viewDir);
    float spec = pow(max(dot(normal, halfVec), 0.0), 32.0);
    float3 specular = spec * light.color.xyz * light.color.w * 0.5;

    return (diffuse + specular) * attenuation;
}

float3 computeSpot(LightData light, VSOutput vertIn)
{
    float3 normal = normalize(vertIn.normal);
    float3 viewDir = normalize(vertIn.viewPos - vertIn.fragPos);

    // Direction du fragment vers la lumière
    float3 lightDir = normalize(light.position.xyz - vertIn.fragPos);

    // Distance et atténuation
    float distance = length(light.position.xyz - vertIn.fragPos);
    float attenuation = 1.0 / (1.0 + light.attenuation * distance * distance);

    // Spot light (cosinus de l'angle entre la direction du spot et la direction vers le fragment)
    float cosAngle = dot(-light.direction.xyz, lightDir);
    float spotFactor = smoothstep(light.outerCosAngle, light.innerCosAngle, cosAngle);

    // Diffuse
    float diff = max(dot(normal, lightDir), 0.0);
    float3 diffuse = diff * light.color.xyz * light.color.w;

    // Specular
    float3 halfVec = normalize(lightDir + viewDir);
    float spec = pow(max(dot(normal, halfVec), 0.0), 32.0);
    float3 specular = spec * light.color.xyz * light.color.w * 0.5;

    return (diffuse + specular) * attenuation * spotFactor;
}

[shader("fragment")]
float4 fragMain(VSOutput vertIn) : SV_Target {
    // Sample textures
    float3 albedo = albedoTexture.Sample(vertIn.uv).rgb;

    // Ambient
    float3 ambient = 0.03 * albedo;

    // Lighting accumulé
    float3 lighting = float3(0.0, 0.0, 0.0);

    // Récupérer les lumières
    LightsBuffer lb = lightsBuffer[0];

    for (int i = 0; i < lb.lightCount; i++) {
        LightData light = lb.lights[i];
        int lightType = (int)light.position.w;

        if (lightType == 0)
            lighting += computeDirectional(light, vertIn);
        else if (lightType == 1)
            lighting += computePoint(light, vertIn);
        else if (lightType == 2)
            lighting += computeSpot(light, vertIn);
    }

    // Résultat final
    float3 finalColor = (ambient + lighting) * albedo;

    // Tone mapping simple (optionnel)
    // finalColor = finalColor / (finalColor + 1.0);

    return float4(finalColor, 1.0);
}