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1 files changed, 180 insertions, 0 deletions

diff --git a/src/texture/texture.cpp b/src/texture/texture.cpp
new file mode 100644
index 0000000..1fa4353
--- /dev/null
+++ b/src/texture/texture.cpp
@@ -0,0 +1,180 @@
+//
+// Created by Michael Foiani on 11/4/23.
+//
+
+#include "raytracer/raytracer.h"
+
+glm::vec2 getUVCube(glm::vec4 pObject) {
+    float u = -1.f,v = -1.f;
+
+    if (RayTracer::floatEquals(pObject.y, -.5f)) // neg y, bottom face
+    {
+        u = pObject.x + 0.5f;
+        v = pObject.z + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.y, .5f)) // pos y, top face
+    {
+        u = pObject.x + 0.5f;
+        v = .5f - pObject.z; // flip z
+    }
+    else if (RayTracer::floatEquals(pObject.x, -.5f)) // neg x, left face
+    {
+        u = pObject.z + 0.5f;
+        v = pObject.y + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.x, .5f)) // pos x, right face
+    {
+        u = .5f - pObject.z; // flip z
+        v = pObject.y + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.z, -.5f)) // neg z, back face
+    {
+        u = .5f - pObject.x; // flip x
+        v = pObject.y + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.z, .5f)) // pos z, front face
+    {
+        u = pObject.x + 0.5f;
+        v = pObject.y + 0.5f;
+    }
+
+    return {u, v};
+}
+
+glm::vec2 getUVCone(glm::vec4 pObject) {
+    float u, v;
+
+    // three cases -> 1) top cap, 2) bottom cap, 3) conical side
+    if (RayTracer::floatEquals(pObject.y, -.5f)) // 1) bottom cap
+    {
+        u = pObject.x + 0.5f;
+        v = pObject.z + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.y, .5f)) // 2) top cap
+    {
+        u = pObject.x + 0.5f;
+        v = 0.5f - pObject.z; // flip z
+    }
+    else // case 3) conical face
+    {
+        // get u from theta zpos and xpos
+        float theta = glm::atan(pObject.x, pObject.z);
+        u = (theta + 1.5 * M_PI) / (2 * M_PI);
+
+        // get v from ypos, trivial
+        v = pObject.y + 0.5f;
+    }
+
+    return {u, v};
+}
+
+glm::vec2 getUVCylinder(glm::vec4 pObject) {
+    float u, v;
+
+    // three cases -> top cap, bottom cap, cylindrical side
+    if (RayTracer::floatEquals(pObject.y, -.5f)) // 1) bottom cap
+    {
+        u = pObject.x + 0.5f;
+        v = pObject.z + 0.5f;
+    }
+    else if (RayTracer::floatEquals(pObject.y, .5f)) // 2) top cap
+    {
+        u = pObject.x + 0.5f;
+        v = 0.5f - pObject.z; // flip z
+    }
+    else // case 3) cylindrical face
+    {
+        // get u from theta zpos and xpos
+        float theta = glm::atan(pObject.x, pObject.z);
+        u = (theta + 1.5 * M_PI) / (2 * M_PI);
+
+        // get v from ypos and origin
+        v = pObject.y + 0.5f;
+    }
+
+    return {u, v};
+}
+
+glm::vec2 getUVMesh(glm::vec4 pObject) {
+    return glm::vec2(-1.f);
+}
+
+glm::vec2 getUVSphere(glm::vec4 pObject) {
+    float u = -1.f,v = -1.f;
+
+    // get u from theta between xpos and zpos
+    // get u from theta zpos and xpos
+    float theta = glm::atan(pObject.x, pObject.z);
+    u = (theta + 1.5 * M_PI) / (2 * M_PI);
+
+    // get v from phi from ypos and origin
+    float height = pObject.y/.5f;
+    height = std::clamp(height, -1.f, 1.f);
+    float phi = glm::asin(height);
+    v = phi / M_PI + .5f;
+
+    return {u, v};
+}
+
+glm::vec4 RayTracer::interpolateTexture(
+        glm::vec4 pObject,
+        const RenderShapeData &shape,
+        glm::vec4 illuminationToInterpolate)
+{
+    auto material = shape.primitive.material;
+    if (!material.textureMap.isUsed)
+    {
+        // return if no texture
+        return illuminationToInterpolate;
+    }
+
+    // determine uv based on shape
+    glm::vec2 uv;
+    switch (shape.primitive.type)
+    {
+        case PrimitiveType::PRIMITIVE_CUBE:
+            uv = getUVCube(pObject);
+            break;
+        case PrimitiveType::PRIMITIVE_CONE:
+            uv = getUVCone(pObject);
+            break;
+        case PrimitiveType::PRIMITIVE_CYLINDER:
+            uv = getUVCylinder(pObject);
+            break;
+        case PrimitiveType::PRIMITIVE_SPHERE:
+            uv = getUVSphere(pObject);
+            break;
+        case PrimitiveType::PRIMITIVE_MESH:
+            uv = getUVMesh(pObject);
+            break;
+    }
+
+    float u = uv.x, v = uv.y;
+    if (u == -1.f) {
+        return illuminationToInterpolate;
+    }
+
+    // map u,v to texture image
+    TextureData textureData = material.textureData;
+    if (textureData.data == nullptr) {
+        return illuminationToInterpolate;
+    }
+
+    int m = material.textureMap.repeatU;
+    int c = (int) glm::floor(u * m * textureData.width) % textureData.width;
+    if (c >= textureData.width) {
+        c = textureData.width - 1;
+    }
+    int n = material.textureMap.repeatV;
+    int r = (int) glm::floor((1-v) * n * textureData.height) % textureData.height;
+    if (r >= textureData.height) {
+        r = textureData.height - 1;
+    }
+    RGBA texture = textureData.data[r * textureData.width + c];
+
+    // interpolate the texture color with the illumination
+    float blend = shape.primitive.material.blend;
+    glm::vec4 blended = blend * (glm::vec4(texture.r, texture.g, texture.b, texture.a) / 255.f)
+                        + (1.f - blend) * illuminationToInterpolate;
+    return blended;
+}
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