[DynamicTerrain] Added slope map computation

- The computed texture has the slope direction in its R & G components, and the strength in its B component

include/Midgard/DynamicTerrain.hpp

@@ -15,6 +15,7 @@ class DynamicTerrain final : public Terrain {
 
   const Raz::Texture2D& getNoiseMap() const noexcept { return *m_noiseMap; }
   const Raz::Texture2D& getColorMap() const noexcept { return *m_colorMap; }
+  const Raz::Texture2D& getSlopeMap() const noexcept { return *m_slopeMap; }
 
   void setMinTessellationLevel(float minTessLevel) { setParameters(minTessLevel, m_heightFactor, m_flatness); }
   void setParameters(float heightFactor, float flatness) override { setParameters(m_minTessLevel, heightFactor, flatness); }
@@ -35,14 +36,18 @@ class DynamicTerrain final : public Terrain {
   void generate(unsigned int width, unsigned int depth, float heightFactor, float flatness, float minTessLevel);
   const Raz::Texture2D& computeNoiseMap(float factor);
   const Raz::Texture2D& computeColorMap();
+  const Raz::Texture2D& computeSlopeMap();
 
 private:
   float m_minTessLevel {};
 
   Raz::ComputeShaderProgram m_noiseProgram {};
   Raz::ComputeShaderProgram m_colorProgram {};
+  Raz::ComputeShaderProgram m_slopeProgram {};
+
   Raz::Texture2DPtr m_noiseMap {};
   Raz::Texture2DPtr m_colorMap {};
+  Raz::Texture2DPtr m_slopeMap {};
 };
 
 #endif // MIDGARD_DYNAMICTERRAIN_HPP

main.cpp

@@ -192,24 +192,26 @@ int main() {
     overlay.addSeparator();
 
 #if !defined(USE_OPENGL_ES)
-    Raz::OverlayTexture& dynamicNoiseTexture = overlay.addTexture(dynamicTerrain.getNoiseMap(), 150, 150);
-    Raz::OverlayTexture& dynamicColorTexture = overlay.addTexture(dynamicTerrain.getColorMap(), 150, 150);
+    Raz::OverlayTexture& dynamicNoiseTexture = overlay.addTexture(dynamicTerrain.getNoiseMap(), 125, 125);
+    Raz::OverlayTexture& dynamicColorTexture = overlay.addTexture(dynamicTerrain.getColorMap(), 125, 125);
+    Raz::OverlayTexture& dynamicSlopeTexture = overlay.addTexture(dynamicTerrain.getSlopeMap(), 125, 125);
 #endif
 
     Raz::Texture2D colorTexture(colorMap, false);
     Raz::Texture2D normalTexture(normalMap, false);
     Raz::Texture2D slopeTexture(slopeMap, false);
 
-    [[maybe_unused]] Raz::OverlayTexture& staticColorTexture  = overlay.addTexture(colorTexture, 150, 150);
-    [[maybe_unused]] Raz::OverlayTexture& staticNormalTexture = overlay.addTexture(normalTexture, 150, 150);
-    [[maybe_unused]] Raz::OverlayTexture& staticSlopeTexture  = overlay.addTexture(slopeTexture, 150, 150);
+    [[maybe_unused]] Raz::OverlayTexture& staticColorTexture  = overlay.addTexture(colorTexture, 125, 125);
+    [[maybe_unused]] Raz::OverlayTexture& staticNormalTexture = overlay.addTexture(normalTexture, 125, 125);
+    [[maybe_unused]] Raz::OverlayTexture& staticSlopeTexture  = overlay.addTexture(slopeTexture, 125, 125);
 
     overlay.addSeparator();
 
 #if !defined(USE_OPENGL_ES)
     Raz::OverlaySlider& dynamicNoiseMapFactorSlider = overlay.addSlider("Noise map factor", [&dynamicTerrain] (float value) {
       dynamicTerrain.computeNoiseMap(value);
       dynamicTerrain.computeColorMap();
+      dynamicTerrain.computeSlopeMap();
     }, 0.001f, 0.1f, 0.01f);
 
     Raz::OverlaySlider& dynamicMinTessLevelSlider = overlay.addSlider("Min tess. level", [&dynamicTerrain] (float value) {
@@ -218,10 +220,12 @@ int main() {
 
     Raz::OverlaySlider& dynamicHeightFactorSlider = overlay.addSlider("Height factor", [&dynamicTerrain] (float value) {
       dynamicTerrain.setHeightFactor(value);
+      dynamicTerrain.computeSlopeMap();
     }, 0.001f, 50.f, 30.f);
 
     Raz::OverlaySlider& dynamicFlatnessSlider = overlay.addSlider("Flatness", [&dynamicTerrain] (float value) {
       dynamicTerrain.setFlatness(value);
+      dynamicTerrain.computeSlopeMap();
     }, 1.f, 10.f, 3.f);
 #endif
 
@@ -249,6 +253,7 @@ int main() {
       dynamicTerrainEntity.enable();
       dynamicNoiseTexture.enable();
       dynamicColorTexture.enable();
+      dynamicSlopeTexture.enable();
       dynamicNoiseMapFactorSlider.enable();
       dynamicMinTessLevelSlider.enable();
       dynamicHeightFactorSlider.enable();
@@ -271,6 +276,7 @@ int main() {
       dynamicTerrainEntity.disable();
       dynamicNoiseTexture.disable();
       dynamicColorTexture.disable();
+      dynamicSlopeTexture.disable();
       dynamicNoiseMapFactorSlider.disable();
       dynamicMinTessLevelSlider.disable();
       dynamicHeightFactorSlider.disable();

shaders/slope.comp

@@ -0,0 +1,24 @@
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+layout(r16f, binding = 0) uniform readonly restrict image2D uniHeightmap;
+layout(rgba16f, binding = 1) uniform writeonly restrict image2D uniSlopeMap;
+
+uniform float uniFlatness     = 3.0;
+uniform float uniHeightFactor = 30.0;
+
+vec2 computeSlope(ivec2 pixelCoords) {
+  float leftHeight  = pow(imageLoad(uniHeightmap, pixelCoords + ivec2(-1,  0)).r, uniFlatness) * uniHeightFactor;
+  float rightHeight = pow(imageLoad(uniHeightmap, pixelCoords + ivec2( 1,  0)).r, uniFlatness) * uniHeightFactor;
+  float topHeight   = pow(imageLoad(uniHeightmap, pixelCoords + ivec2( 0, -1)).r, uniFlatness) * uniHeightFactor;
+  float botHeight   = pow(imageLoad(uniHeightmap, pixelCoords + ivec2( 0,  1)).r, uniFlatness) * uniHeightFactor;
+
+  return vec2(leftHeight - rightHeight, topHeight - botHeight);
+}
+
+void main() {
+  ivec2 pixelCoords = ivec2(gl_GlobalInvocationID.xy);
+
+  vec2 slopeVec       = computeSlope(pixelCoords);
+  float slopeStrength = length(slopeVec) * 0.5;
+  imageStore(uniSlopeMap, pixelCoords, vec4(normalize(slopeVec), slopeStrength, 1.0));
+}

src/Midgard/DynamicTerrain.cpp

@@ -26,6 +26,10 @@ constexpr std::string_view colorCompSource = {
 #include "terrain_color.comp.embed"
 };
 
+constexpr std::string_view slopeCompSource = {
+#include "slope.comp.embed"
+};
+
 inline void checkParameters(float& minTessLevel) {
   if (minTessLevel <= 0.f) {
     Raz::Logger::warn("[DynamicTerrain] The minimal tessellation level can't be 0 or negative; remapping to +epsilon.");
@@ -43,11 +47,13 @@ DynamicTerrain::DynamicTerrain(Raz::Entity& entity) : Terrain(entity) {
 
   m_noiseMap = Raz::Texture2D::create(heightmapSize, heightmapSize, Raz::TextureColorspace::GRAY, Raz::TextureDataType::FLOAT16);
   m_colorMap = Raz::Texture2D::create(heightmapSize, heightmapSize, Raz::TextureColorspace::RGBA, Raz::TextureDataType::BYTE);
+  m_slopeMap = Raz::Texture2D::create(heightmapSize, heightmapSize, Raz::TextureColorspace::RGBA, Raz::TextureDataType::FLOAT16);
 
 #if !defined(USE_OPENGL_ES)
   if (Raz::Renderer::checkVersion(4, 3)) {
     Raz::Renderer::setLabel(Raz::RenderObjectType::TEXTURE, m_noiseMap->getIndex(), "Noise map");
     Raz::Renderer::setLabel(Raz::RenderObjectType::TEXTURE, m_colorMap->getIndex(), "Color map");
+    Raz::Renderer::setLabel(Raz::RenderObjectType::TEXTURE, m_slopeMap->getIndex(), "Slope map");
   }
 #endif
 
@@ -59,10 +65,15 @@ DynamicTerrain::DynamicTerrain(Raz::Entity& entity) : Terrain(entity) {
   m_colorProgram.setImageTexture(m_noiseMap, "uniHeightmap", Raz::ImageTextureUsage::READ);
   m_colorProgram.setImageTexture(m_colorMap, "uniColorMap", Raz::ImageTextureUsage::WRITE);
 
+  m_slopeProgram.setShader(Raz::ComputeShader::loadFromSource(slopeCompSource));
+  m_slopeProgram.setImageTexture(m_noiseMap, "uniHeightmap", Raz::ImageTextureUsage::READ);
+  m_slopeProgram.setImageTexture(m_slopeMap, "uniSlopeMap", Raz::ImageTextureUsage::WRITE);
+
   terrainProgram.setTexture(m_noiseMap, "uniHeightmap");
   terrainProgram.setTexture(m_colorMap, Raz::MaterialTexture::BaseColor);
 
   computeNoiseMap(0.01f);
+  computeSlopeMap();
   computeColorMap();
 }
 
@@ -86,6 +97,10 @@ void DynamicTerrain::setParameters(float minTessLevel, float heightFactor, float
   terrainProgram.setAttribute(m_heightFactor, "uniHeightFactor");
   terrainProgram.setAttribute(m_flatness, "uniFlatness");
   terrainProgram.sendAttributes();
+
+  m_slopeProgram.setAttribute(m_heightFactor, "uniHeightFactor");
+  m_slopeProgram.setAttribute(m_flatness, "uniFlatness");
+  m_slopeProgram.sendAttributes();
 }
 
 void DynamicTerrain::generate(unsigned int width, unsigned int depth, float heightFactor, float flatness, float minTessLevel) {
@@ -158,3 +173,9 @@ const Raz::Texture2D& DynamicTerrain::computeColorMap() {
 
   return *m_colorMap;
 }
+
+const Raz::Texture2D& DynamicTerrain::computeSlopeMap() {
+  m_slopeProgram.execute(heightmapSize, heightmapSize);
+
+  return *m_slopeMap;
+}