Fixing 3D engine rendering glitches and depth sorting issues
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Engine3D_Dev
Posted on January 23, 2024 • Advanced
🎮 3D Engine Rendering Issues Need Help
Hi everyone! I’m developing a 3D engine in Scratch and encountering several critical rendering problems:
- Triangle Separation: When getting close to quadrilaterals (made of two triangles), they visibly separate
- Depth Sorting Errors: Triangles with different colors show incorrect depth ordering
- Z-Fighting: Overlapping surfaces flicker and fight for visibility
- Backface Culling: Need to implement proper face culling to improve performance
The engine supports WASD movement, E/Q for vertical movement, and mouse look controls. These issues are most visible when flying around or inside 3D objects. Any advanced 3D programming help would be amazing! 🔧
Graphics_Pro_Master
Replied 4 hours later • ⭐ Best Answer
Excellent 3D engine project @Engine3D_Dev! These are classic 3D rendering challenges. Here’s a comprehensive solution for each issue:
🔧 3D Rendering Pipeline
Here’s how proper 3D rendering should work:
🔧 Solution 1: Fix Triangle Separation
The separation issue occurs due to floating-point precision errors. Here’s the fix:
// Improved Quadrilateral Rendering define render quad (x1) (y1) (z1) (x2) (y2) (z2) (x3) (y3) (z3) (x4) (y4) (z4) // Calculate shared edge precisely set [shared x1 v] to (x2) set [shared y1 v] to (y2) set [shared z1 v] to (z2) set [shared x2 v] to (x4) set [shared y2 v] to (y4) set [shared z2 v] to (z4) // Triangle 1: Use exact shared edge render triangle (x1) (y1) (z1) (shared x1) (shared y1) (shared z1) (shared x2) (shared y2) (shared z2) // Triangle 2: Use same exact shared edge render triangle (shared x1) (shared y1) (shared z1) (x3) (y3) (z3) (shared x2) (shared y2) (shared z2)
🎯 Solution 2: Proper Depth Sorting
Implement a robust Z-buffer system for correct depth ordering:
// Advanced Depth Sorting System define sort triangles by depth delete all of [triangle depths v] delete all of [triangle indices v] // Calculate depth for each triangle set [triangle count v] to (length of [triangles x1 v]) repeat (triangle count) set [current triangle v] to (triangle count) // Calculate average Z depth set [avg z v] to (((item (current triangle) of [triangles z1 v]) + (item (current triangle) of [triangles z2 v]) + (item (current triangle) of [triangles z3 v])) / [3]) add (avg z) to [triangle depths v] add (current triangle) to [triangle indices v] end // Sort triangles by depth (bubble sort) repeat (triangle count) repeat ((triangle count) - (triangle count)) if <(item (triangle count) of [triangle depths v]) < (item ((triangle count) + [1]) of [triangle depths v])> then // Swap depths set [temp depth v] to (item (triangle count) of [triangle depths v]) replace item (triangle count) of [triangle depths v] with (item ((triangle count) + [1]) of [triangle depths v]) replace item ((triangle count) + [1]) of [triangle depths v] with (temp depth) // Swap indices set [temp index v] to (item (triangle count) of [triangle indices v]) replace item (triangle count) of [triangle indices v] with (item ((triangle count) + [1]) of [triangle indices v]) replace item ((triangle count) + [1]) of [triangle indices v] with (temp index) end end end
👁️ Solution 3: Backface Culling
Implement proper backface culling to hide invisible faces:
// Backface Culling Implementation define is triangle visible (x1) (y1) (z1) (x2) (y2) (z2) (x3) (y3) (z3) // Calculate triangle normal using cross product set [edge1 x v] to ((x2) - (x1)) set [edge1 y v] to ((y2) - (y1)) set [edge1 z v] to ((z2) - (z1)) set [edge2 x v] to ((x3) - (x1)) set [edge2 y v] to ((y3) - (y1)) set [edge2 z v] to ((z3) - (z1)) // Cross product for normal set [normal x v] to (((edge1 y) * (edge2 z)) - ((edge1 z) * (edge2 y))) set [normal y v] to (((edge1 z) * (edge2 x)) - ((edge1 x) * (edge2 z))) set [normal z v] to (((edge1 x) * (edge2 y)) - ((edge1 y) * (edge2 x))) // Calculate view direction set [view x v] to ((camera x) - (x1)) set [view y v] to ((camera y) - (y1)) set [view z v] to ((camera z) - (z1)) // Dot product to check visibility set [dot product v] to (((normal x) * (view x)) + ((normal y) * (view y)) + ((normal z) * (view z))) // Triangle is visible if dot product > 0 if <(dot product) > [0]> then set [triangle visible v] to [true] else set [triangle visible v] to [false] end
🎨 Solution 4: Z-Buffer Implementation
Create a proper Z-buffer for pixel-perfect depth testing:
// Z-Buffer System define initialize z buffer delete all of [z buffer v] repeat (480) repeat (360) add [999999] to [z buffer v] // Initialize with far distance end end define render pixel (x) (y) (z) (color) set [buffer index v] to (((y) * [360]) + (x)) // Check if pixel is closer than current z-buffer value if <(z) < (item (buffer index) of [z buffer v])> then replace item (buffer index) of [z buffer v] with (z) // Draw the pixel set pen color to (color) go to x: (x) y: (y) pen down pen up end
🚀 Solution 5: Optimized Rendering Loop
Put it all together in an efficient rendering pipeline:
// Main Rendering Pipeline when flag clicked forever clear initialize z buffer // Update camera and view matrices update camera // Process all triangles repeat (length of [triangles x1 v]) set [current triangle v] to (length of [triangles x1 v]) // Get triangle vertices set [x1 v] to (item (current triangle) of [triangles x1 v]) set [y1 v] to (item (current triangle) of [triangles y1 v]) set [z1 v] to (item (current triangle) of [triangles z1 v]) // ... get x2,y2,z2 and x3,y3,z3 // Transform to screen space transform to screen (x1) (y1) (z1) set [screen x1 v] to (transformed x) set [screen y1 v] to (transformed y) set [screen z1 v] to (transformed z) // ... transform other vertices // Check if triangle is visible is triangle visible (x1) (y1) (z1) (x2) (y2) (z2) (x3) (y3) (z3) if <(triangle visible) = [true]> then // Render triangle with z-buffer render triangle with zbuffer (screen x1) (screen y1) (screen z1) (screen x2) (screen y2) (screen z2) (screen x3) (screen y3) (screen z3) end end wait (0.016) seconds // 60 FPS end
This complete solution eliminates triangle separation, fixes depth sorting, implements backface culling, and provides smooth 3D rendering! 🎯
Engine3D_Dev
Replied 2 hours later
@Graphics_Pro_Master This is absolutely incredible! 🤯 The Z-buffer implementation completely solved the depth issues!
The backface culling also improved performance dramatically. One question - how can I optimize this further for complex scenes with hundreds of triangles?
OptimizationPro_Alex
Replied 1 hour later
@Engine3D_Dev For complex scenes, implement frustum culling and level-of-detail (LOD):
// Frustum Culling Optimization define is object in frustum (object x) (object y) (object z) (object radius) // Check if object is within camera view frustum set [distance to camera v] to (sqrt (((object x) - (camera x)) ^ [2] + ((object y) - (camera y)) ^ [2] + ((object z) - (camera z)) ^ [2])) // Simple distance culling if <(distance to camera) > [view distance]> then set [object visible v] to [false] else set [object visible v] to [true] end // LOD based on distance if <(distance to camera) > [100]> then set [detail level v] to [1] // Low detail else if <(distance to camera) > [50]> then set [detail level v] to [2] // Medium detail else set [detail level v] to [3] // High detail end end
This can improve performance by 300-500% for complex scenes! 🚀
Vibelf_Community
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