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| Original file line number | Diff line number | Diff line change |
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| ## Info on the lighting implementation | ||
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| ### Missing shadow attenuation | ||
| Shadow attenuation samples a texture unit, and that likely needs render to texture for most games so that they can construct | ||
| their shadow map. As such the colors are not multiplied by the shadow attenuation value, so there's no shadows. | ||
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| ### Missing bump mapping | ||
| Bump mapping also samples a texture unit, most likely doesn't need render to texture however may need better texture sampling | ||
| implementation (such as GPUREG_TEXUNITi_BORDER_COLOR, GPUREG_TEXUNITi_BORDER_PARAM). Bump mapping would work for some things, | ||
| namely the 3ds-examples bump mapping demo, but would break others such as Toad Treasure Tracker with a naive `texture` implementation. | ||
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| Also the CP configuration is missing, because it needs a tangent map implementation. It is currently marked with error_unimpl. | ||
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| ### samplerEnabledBitfields | ||
| Holds the enabled state of the lighting samples for various PICA configurations | ||
| As explained in https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTING_CONFIG0 | ||
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| ```c | ||
| const bool samplerEnabled[9 * 7] = bool[9 * 7]( | ||
| // D0 D1 SP FR RB RG RR | ||
| true, false, true, false, false, false, true, // Configuration 0: D0, SP, RR | ||
| false, false, true, true, false, false, true, // Configuration 1: FR, SP, RR | ||
| true, true, false, false, false, false, true, // Configuration 2: D0, D1, RR | ||
| true, true, false, true, false, false, false, // Configuration 3: D0, D1, FR | ||
| true, true, true, false, true, true, true, // Configuration 4: All except for FR | ||
| true, false, true, true, true, true, true, // Configuration 5: All except for D1 | ||
| true, true, true, true, false, false, true, // Configuration 6: All except for RB and RG | ||
| false, false, false, false, false, false, false, // Configuration 7: Unused | ||
| true, true, true, true, true, true, true // Configuration 8: All | ||
| ); | ||
| ``` | ||
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| The above has been condensed to two uints for performance reasons. | ||
| You can confirm they are the same by running the following: | ||
| ```c | ||
| const uint samplerEnabledBitfields[2] = { 0x7170e645u, 0x7f013fefu }; | ||
| for (int i = 0; i < 9 * 7; i++) { | ||
| unsigned arrayIndex = (i >> 5); | ||
| bool b = (samplerEnabledBitfields[arrayIndex] & (1u << (i & 31))) != 0u; | ||
| if (samplerEnabled[i] == b) { | ||
| printf("%d: happy\n", i); | ||
| } else { | ||
| printf("%d: unhappy\n", i); | ||
| } | ||
| } | ||
| ``` | ||
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| ### lightLutLookup | ||
| lut_id is one of these values | ||
| 0 D0 | ||
| 1 D1 | ||
| 2 SP | ||
| 3 FR | ||
| 4 RB | ||
| 5 RG | ||
| 6 RR | ||
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| lut_index on the other hand represents the actual index of the LUT in the texture | ||
| u_tex_lighting_lut has 24 LUTs and they are used like so: | ||
| 0 D0 | ||
| 1 D1 | ||
| 2 is missing because SP uses LUTs 8-15 | ||
| 3 FR | ||
| 4 RB | ||
| 5 RG | ||
| 6 RR | ||
| 8-15 SP0-7 | ||
| 16-23 DA0-7, but this is not handled in this function as the lookup is a bit different | ||
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| The light environment configuration controls which LUTs are available for use | ||
| If a LUT is not available in the selected configuration, its value will always read a constant 1.0 regardless of the enable state in GPUREG_LIGHTING_CONFIG1 | ||
| If RR is enabled but not RG or RB, the output of RR is used for the three components; Red, Green and Blue. | ||
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| ### Distance attenuation | ||
| Distance attenuation is computed differently from the other factors, for example | ||
| it doesn't store its scale in GPUREG_LIGHTING_LUTINPUT_SCALE and it doesn't use | ||
| GPUREG_LIGHTING_LUTINPUT_SELECT. Instead, it uses the distance from the light to the | ||
| fragment and the distance attenuation scale and bias to calculate where in the LUT to look up. | ||
| See: https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTi_ATTENUATION_SCALE |
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