nv2a: Implement texture LOD bias

Author: abaire

hw/xbox/nv2a/pgraph/gl/renderer.h

@@ -73,6 +73,7 @@ typedef struct TextureBinding {
     unsigned int scale;
     unsigned int min_filter;
     unsigned int mag_filter;
+    uint32_t lod_bias;
     unsigned int addru;
     unsigned int addrv;
     unsigned int addrp;

hw/xbox/nv2a/pgraph/gl/texture.c

@@ -117,6 +117,8 @@ static void apply_texture_parameters(TextureBinding *binding,
 {
     unsigned int min_filter = GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MIN);
     unsigned int mag_filter = GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MAG);
+    unsigned int lod_bias =
+        GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS);
     unsigned int addru = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRU);
     unsigned int addrv = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRV);
     unsigned int addrp = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRP);
@@ -146,6 +148,11 @@ static void apply_texture_parameters(TextureBinding *binding,
                         pgraph_texture_mag_filter_gl_map[mag_filter]);
         binding->mag_filter = mag_filter;
     }
+    if (lod_bias != binding->lod_bias) {
+        binding->lod_bias = lod_bias;
+        glTexParameterf(binding->gl_target, GL_TEXTURE_LOD_BIAS,
+                        pgraph_convert_lod_bias_to_float(lod_bias));
+    }
 
     /* Texture wrapping */
     assert(addru < ARRAY_SIZE(pgraph_texture_addr_gl_map));
@@ -727,6 +734,7 @@ static TextureBinding* generate_texture(const TextureShape s,
     ret->data_hash = 0;
     ret->min_filter = 0xFFFFFFFF;
     ret->mag_filter = 0xFFFFFFFF;
+    ret->lod_bias = 0xFFFFFFFF;
     ret->addru = 0xFFFFFFFF;
     ret->addrv = 0xFFFFFFFF;
     ret->addrp = 0xFFFFFFFF;

hw/xbox/nv2a/pgraph/texture.h

@@ -64,4 +64,13 @@ hwaddr pgraph_get_texture_palette_phys_addr_length(PGRAPHState *pg, int texture_
 TextureShape pgraph_get_texture_shape(PGRAPHState *pg, int texture_idx);
 size_t pgraph_get_texture_length(PGRAPHState *pg, TextureShape *shape);
 
+static inline float pgraph_convert_lod_bias_to_float(uint32_t lod_bias)
+{
+    int sign_extended_bias = lod_bias;
+    if (lod_bias & (1 << 12)) {
+        sign_extended_bias |= ~NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS;
+    }
+    return (float)sign_extended_bias / 256.f;
+}
+
 #endif

hw/xbox/nv2a/pgraph/vk/texture.c

@@ -1336,6 +1336,14 @@ static void create_texture(PGRAPHState *pg, int texture_idx)
         min_filter == NV_PGRAPH_TEXFILTER0_MIN_BOX_NEARESTLOD ||
         min_filter == NV_PGRAPH_TEXFILTER0_MIN_TENT_NEARESTLOD;
 
+    float lod_bias = pgraph_convert_lod_bias_to_float(
+        GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS));
+    if (lod_bias > r->device_props.limits.maxSamplerLodBias) {
+        lod_bias = r->device_props.limits.maxSamplerLodBias;
+    } else if (lod_bias < -r->device_props.limits.maxSamplerLodBias) {
+        lod_bias = -r->device_props.limits.maxSamplerLodBias;
+    }
+
     VkSamplerCreateInfo sampler_create_info = {
         .sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO,
         .magFilter = vk_mag_filter,
@@ -1356,7 +1364,7 @@ static void create_texture(PGRAPHState *pg, int texture_idx)
                                        VK_SAMPLER_MIPMAP_MODE_LINEAR,
         .minLod = mipmap_en ? MIN(state.min_mipmap_level, state.levels - 1) : 0.0,
         .maxLod = mipmap_en ? MIN(state.max_mipmap_level, state.levels - 1) : 0.0,
-        .mipLodBias = 0.0,
+        .mipLodBias = lod_bias,
         .pNext = sampler_next_struct,
     };