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2018-soft-3d-renderer
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Add alpha blending of transparent textures

This commit is contained in:
Austin Morlan 2018-09-19 19:16:14 -07:00
parent abf9e8fa7c
commit ba68f22bee
Signed by: austin
GPG Key ID: FD6B27654AF5E348
3 changed files with 54 additions and 28 deletions
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14
src/engine.cpp
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@ -64,7 +64,7 @@ int EngineInit(char *objFilename, char *mtlFilename)
// Mesh configuration // Mesh configuration
mesh.position.z = 175; mesh.position.z = 50;
mesh.position.y = -175; mesh.position.y = -175;
mesh.scale = 1.0f; mesh.scale = 1.0f;
@ -152,29 +152,29 @@ static void CheckInputs(uint32_t input)
if (CHECK_BIT(input, ROTATE_X_POS)) if (CHECK_BIT(input, ROTATE_X_POS))
{ {
mesh.position.x += 10; mesh.rotation.x += 0.10f;
} }
else if (CHECK_BIT(input, ROTATE_X_NEG)) else if (CHECK_BIT(input, ROTATE_X_NEG))
{ {
mesh.position.x -= 10; mesh.rotation.x -= 0.10f;
} }
if (CHECK_BIT(input, ROTATE_Y_POS)) if (CHECK_BIT(input, ROTATE_Y_POS))
{ {
mesh.position.y += 10; mesh.rotation.y += 0.10f;
} }
else if (CHECK_BIT(input, ROTATE_Y_NEG)) else if (CHECK_BIT(input, ROTATE_Y_NEG))
{ {
mesh.position.y -= 10; mesh.rotation.y -= 0.10f;
} }
if (CHECK_BIT(input, ROTATE_Z_POS)) if (CHECK_BIT(input, ROTATE_Z_POS))
{ {
mesh.position.z += 10; mesh.rotation.z += 0.10f;
} }
else if (CHECK_BIT(input, ROTATE_Z_NEG)) else if (CHECK_BIT(input, ROTATE_Z_NEG))
{ {
mesh.position.z -= 10; mesh.rotation.z -= 0.10f;
} }
if (CHECK_BIT(input, SCALE_UP)) if (CHECK_BIT(input, SCALE_UP))

9
src/loader.cpp
View File

@ -8,7 +8,7 @@
// STATIC PROTOTYPES // STATIC PROTOTYPES
static int LoadTexture(char *filename, Texture &texture); static int LoadTexture(char *filename, Texture &texture, float opacity);
#pragma pack(push, 1) #pragma pack(push, 1)
@ -194,7 +194,9 @@ int ParseMTL(char *filename, EngineMemory &memory)
{ {
char *textureFilename = data; char *textureFilename = data;
textureFilename[strcspn(textureFilename, "\r\n")] = 0; textureFilename[strcspn(textureFilename, "\r\n")] = 0;
LoadTexture(textureFilename, textures.data[materialIndex]); LoadTexture(
textureFilename, textures.data[materialIndex],
materials.data[materialIndex].opacity);
} }
} }
} }
@ -204,7 +206,7 @@ int ParseMTL(char *filename, EngineMemory &memory)
return 0; return 0;
} }
static int LoadTexture(char *filename, Texture &texture) static int LoadTexture(char *filename, Texture &texture, float opacity)
{ {
FILE *fp = fopen(filename, "r"); FILE *fp = fopen(filename, "r");
if (fp == NULL) if (fp == NULL)
@ -227,6 +229,7 @@ static int LoadTexture(char *filename, Texture &texture)
fread(&texture.texels[y][x].b, 1, 1, fp); fread(&texture.texels[y][x].b, 1, 1, fp);
fread(&texture.texels[y][x].g, 1, 1, fp); fread(&texture.texels[y][x].g, 1, 1, fp);
fread(&texture.texels[y][x].r, 1, 1, fp); fread(&texture.texels[y][x].r, 1, 1, fp);
texture.texels[y][x].a = (uint8_t)(255 * opacity);
} }
// Discard padding byte // Discard padding byte

59
src/render.cpp
View File

@ -114,24 +114,32 @@ void Render(EngineBuffer &buffer, EngineMemory &memory)
float duDiff = 1 - du; float duDiff = 1 - du;
float dvDiff = 1 - dv; float dvDiff = 1 - dv;
ColorU32 color; ColorU32 color =
color.b = (uint8_t) {
(duDiff * dvDiff * texture.texels[v][u].b (uint8_t)
+ du * dvDiff * texture.texels[v][u+1].b (duDiff * dvDiff * texture.texels[v][u].b
+ du * dv * texture.texels[v+1][u+1].b + du * dvDiff * texture.texels[v][u+1].b
+ duDiff * dv * texture.texels[v+1][u].b); + du * dv * texture.texels[v+1][u+1].b
+ duDiff * dv * texture.texels[v+1][u].b),
color.g = (uint8_t) (uint8_t)
(duDiff * dvDiff * texture.texels[v][u].g (duDiff * dvDiff * texture.texels[v][u].g
+ du * dvDiff * texture.texels[v][u+1].g + du * dvDiff * texture.texels[v][u+1].g
+ du * dv * texture.texels[v+1][u+1].g + du * dv * texture.texels[v+1][u+1].g
+ duDiff * dv * texture.texels[v+1][u].g); + duDiff * dv * texture.texels[v+1][u].g),
color.r = (uint8_t) (uint8_t)
(duDiff * dvDiff * texture.texels[v][u].r (duDiff * dvDiff * texture.texels[v][u].r
+ du * dvDiff * texture.texels[v][u+1].r + du * dvDiff * texture.texels[v][u+1].r
+ du * dv * texture.texels[v+1][u+1].r + du * dv * texture.texels[v+1][u+1].r
+ duDiff * dv * texture.texels[v+1][u].r); + duDiff * dv * texture.texels[v+1][u].r),
(uint8_t)
(duDiff * dvDiff * texture.texels[v][u].a
+ du * dvDiff * texture.texels[v][u+1].a
+ du * dv * texture.texels[v+1][u+1].a
+ duDiff * dv * texture.texels[v+1][u].a)
};
// Perform Gouraud shading on the texture // Perform Gouraud shading on the texture
@ -145,7 +153,7 @@ void Render(EngineBuffer &buffer, EngineMemory &memory)
+ (barycenter[2] * c2); + (barycenter[2] * c2);
// Ensure no color channel exceeds 1.0 // Ensure no color channel exceeds max
ScaleColor(shading); ScaleColor(shading);
@ -154,6 +162,7 @@ void Render(EngineBuffer &buffer, EngineMemory &memory)
color.g *= shading.g; color.g *= shading.g;
color.r *= shading.r; color.r *= shading.r;
// Interpolate 1/z for the z-buffer // Interpolate 1/z for the z-buffer
float zInv = float zInv =
1.0f / 1.0f /
@ -165,7 +174,21 @@ void Render(EngineBuffer &buffer, EngineMemory &memory)
// Draw the pixel if it's closer than what's in the z-buffer // Draw the pixel if it's closer than what's in the z-buffer
if (zInv > memory.zbuffer[y][x]) if (zInv > memory.zbuffer[y][x])
{ {
DrawPixel(buffer.buffer, buffer.width, color.u32, x, y); ColorU32 *pixel = (ColorU32*)&buffer.buffer[y*buffer.width+x];
float alpha = color.a / 255.0f;
float alphaDiff = 1.0f - alpha;
// Blend new color with the existing color
ColorU32 blended =
{
(uint8_t)((alpha * color.b) + (alphaDiff * pixel->b)),
(uint8_t)((alpha * color.g) + (alphaDiff * pixel->g)),
(uint8_t)((alpha * color.r) + (alphaDiff * pixel->r)),
(uint8_t)((alpha * color.a) + (alphaDiff * pixel->a))
};
DrawPixel(buffer.buffer, buffer.width, blended.u32, x, y);
memory.zbuffer[y][x] = zInv; memory.zbuffer[y][x] = zInv;
} }