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Move documentation, sign extend spot dir
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79
docs/3ds/lighting.md
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79
docs/3ds/lighting.md
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## Info on the lighting implementation
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### Missing shadow attenuation
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Shadow attenuation samples a texture unit, and that likely needs render to texture for most games so that they can construct
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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
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Bump mapping also samples a texture unit, most likely doesn't need render to texture however may need better texture sampling
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implementation (such as GPUREG_TEXUNITi_BORDER_COLOR, GPUREG_TEXUNITi_BORDER_PARAM). Bump mapping would work for some things,
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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
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Holds the enabled state of the lighting samples for various PICA configurations
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As explained in https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTING_CONFIG0
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```c
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const bool samplerEnabled[9 * 7] = bool[9 * 7](
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// D0 D1 SP FR RB RG RR
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true, false, true, false, false, false, true, // Configuration 0: D0, SP, RR
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false, false, true, true, false, false, true, // Configuration 1: FR, SP, RR
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true, true, false, false, false, false, true, // Configuration 2: D0, D1, RR
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true, true, false, true, false, false, false, // Configuration 3: D0, D1, FR
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true, true, true, false, true, true, true, // Configuration 4: All except for FR
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true, false, true, true, true, true, true, // Configuration 5: All except for D1
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true, true, true, true, false, false, true, // Configuration 6: All except for RB and RG
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false, false, false, false, false, false, false, // Configuration 7: Unused
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true, true, true, true, true, true, true // Configuration 8: All
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);
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```
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The above has been condensed to two uints for performance reasons.
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You can confirm they are the same by running the following:
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```c
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const uint samplerEnabledBitfields[2] = { 0x7170e645u, 0x7f013fefu };
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for (int i = 0; i < 9 * 7; i++) {
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unsigned arrayIndex = (i >> 5);
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bool b = (samplerEnabledBitfields[arrayIndex] & (1u << (i & 31))) != 0u;
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if (samplerEnabled[i] == b) {
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printf("%d: happy\n", i);
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} else {
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printf("%d: unhappy\n", i);
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}
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}
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```
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### lightLutLookup
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lut_id is one of these values
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0 D0
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1 D1
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2 SP
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3 FR
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4 RB
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5 RG
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6 RR
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lut_index on the other hand represents the actual index of the LUT in the texture
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u_tex_lighting_lut has 24 LUTs and they are used like so:
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0 D0
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1 D1
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2 is missing because SP uses LUTs 8-15
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3 FR
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4 RB
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5 RG
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6 RR
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8-15 SP0-7
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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
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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
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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
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Distance attenuation is computed differently from the other factors, for example
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it doesn't store its scale in GPUREG_LIGHTING_LUTINPUT_SCALE and it doesn't use
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GPUREG_LIGHTING_LUTINPUT_SELECT. Instead, it uses the distance from the light to the
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fragment and the distance attenuation scale and bias to calculate where in the LUT to look up.
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See: https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTi_ATTENUATION_SCALE
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@ -37,32 +37,7 @@ vec4 tevNextPreviousBuffer;
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bool tevUnimplementedSourceFlag = false;
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vec3 normal;
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// Holds the enabled state of the lighting samples for various PICA configurations
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// As explained in https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTING_CONFIG0
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// const bool samplerEnabled[9 * 7] = bool[9 * 7](
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// // D0 D1 SP FR RB RG RR
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// true, false, true, false, false, false, true, // Configuration 0: D0, SP, RR
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// false, false, true, true, false, false, true, // Configuration 1: FR, SP, RR
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// true, true, false, false, false, false, true, // Configuration 2: D0, D1, RR
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// true, true, false, true, false, false, false, // Configuration 3: D0, D1, FR
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// true, true, true, false, true, true, true, // Configuration 4: All except for FR
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// true, false, true, true, true, true, true, // Configuration 5: All except for D1
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// true, true, true, true, false, false, true, // Configuration 6: All except for RB and RG
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// false, false, false, false, false, false, false, // Configuration 7: Unused
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// true, true, true, true, true, true, true // Configuration 8: All
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// );
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// The above have been condensed to two uints to save space
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// You can confirm they are the same by running the following:
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// for (int i = 0; i < 9 * 7; i++) {
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// unsigned arrayIndex = (i >> 5);
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// bool b = (samplerEnabledBitfields[arrayIndex] & (1u << (i & 31))) != 0u;
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// if (samplerEnabled[i] == b) {
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// printf("%d: happy\n", i);
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// } else {
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// printf("%d: unhappy\n", i);
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// }
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// }
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// See docs/lighting.md
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const uint samplerEnabledBitfields[2] = uint[2](0x7170e645u, 0x7f013fefu);
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bool isSamplerEnabled(uint environment_id, uint lut_id) {
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@ -219,27 +194,6 @@ float decodeFP(uint hex, uint E, uint M) {
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float lightLutLookup(uint environment_id, uint lut_id, uint light_id, vec3 light_vector, vec3 half_vector) {
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uint lut_index;
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// lut_id is one of these values
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// 0 D0
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// 1 D1
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// 2 SP
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// 3 FR
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// 4 RB
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// 5 RG
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// 6 RR
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// lut_index on the other hand represents the actual index of the LUT in the texture
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// u_tex_lighting_lut has 24 LUTs and they are used like so:
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// 0 D0
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// 1 D1
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// 2 is missing because SP uses LUTs 8-15
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// 3 FR
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// 4 RB
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// 5 RG
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// 6 RR
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// 8-15 SP0-7
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// 16-23 DA0-7, but this is not handled in this function as the lookup is a bit different
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int bit_in_config1;
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if (lut_id == SP_LUT) {
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// These are the spotlight attenuation LUTs
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@ -252,9 +206,6 @@ float lightLutLookup(uint environment_id, uint lut_id, uint light_id, vec3 light
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error_unimpl = true;
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}
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// The light environment configuration controls which LUTs are available for use
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// 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
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// 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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bool current_sampler_enabled = isSamplerEnabled(environment_id, lut_id); // 7 luts per environment
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if (!current_sampler_enabled || (bitfieldExtract(GPUREG_LIGHTING_CONFIG1, bit_in_config1, 1) != 0u)) {
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@ -285,14 +236,23 @@ float lightLutLookup(uint environment_id, uint lut_id, uint light_id, vec3 light
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break;
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}
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case 4u: {
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// These are ints so that bitfieldExtract sign extends for us
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int GPUREG_LIGHTi_SPOTDIR_LOW = int(readPicaReg(0x0146u + (light_id << 4u)));
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int GPUREG_LIGHTi_SPOTDIR_HIGH = int(readPicaReg(0x0147u + (light_id << 4u)));
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uint GPUREG_LIGHTi_SPOTDIR_LOW = readPicaReg(0x0146u + (light_id << 4u));
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uint GPUREG_LIGHTi_SPOTDIR_HIGH = readPicaReg(0x0147u + (light_id << 4u));
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// Sign extend them. Normally bitfieldExtract would do that but it's missing on some versions
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// of GLSL so we do it manually
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int se_x = bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_LOW, 0, 13);
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int se_y = bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_LOW, 16, 13);
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int se_z = bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_HIGH, 0, 13);
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if (se_x & 0x1000) se_x |= 0xffffe000;
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if (se_y & 0x1000) se_y |= 0xffffe000;
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if (se_z & 0x1000) se_z |= 0xffffe000;
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// These are fixed point 1.1.11 values, so we need to convert them to float
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float x = float(bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_LOW, 0, 13)) / 2047.0;
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float y = float(bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_LOW, 16, 13)) / 2047.0;
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float z = float(bitfieldExtract(GPUREG_LIGHTi_SPOTDIR_HIGH, 0, 13)) / 2047.0;
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float x = float(se_x) / 2047.0;
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float y = float(se_y) / 2047.0;
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float z = float(se_z) / 2047.0;
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vec3 spotlight_vector = vec3(x, y, z);
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delta = dot(light_vector, spotlight_vector); // spotlight direction is negated so we don't negate light_vector
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break;
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@ -359,7 +319,6 @@ void calcLighting(out vec4 primary_color, out vec4 secondary_color) {
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uint bump_mode = bitfieldExtract(GPUREG_LIGHTING_CONFIG0, 28, 2);
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// Bump mode is ignored for now because it breaks some games ie. Toad Treasure Tracker
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// Could be because the texture is not sampled correctly, may need the clamp/border color configurations
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switch (bump_mode) {
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default: {
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normal = rotateVec3ByQuaternion(vec3(0.0, 0.0, 1.0), v_quaternion);
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@ -424,11 +383,6 @@ void calcLighting(out vec4 primary_color, out vec4 secondary_color) {
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geometric_factor = geometric_factor == 0.0 ? 0.0 : min(NdotL / geometric_factor, 1.0);
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}
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// Distance attenuation is computed differently from the other factors, for example
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// it doesn't store its scale in GPUREG_LIGHTING_LUTINPUT_SCALE and it doesn't use
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// GPUREG_LIGHTING_LUTINPUT_SELECT. Instead, it uses the distance from the light to the
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// fragment and the distance attenuation scale and bias to calculate where in the LUT to look up.
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// See: https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_LIGHTi_ATTENUATION_SCALE
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float distance_attenuation = 1.0;
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if (bitfieldExtract(GPUREG_LIGHTING_CONFIG1, 24 + int(light_id), 1) == 0u) {
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uint GPUREG_LIGHTi_ATTENUATION_BIAS = bitfieldExtract(readPicaReg(0x014Au + (light_id << 4u)), 0, 20);
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